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Objective: To compare the sensitivity of alternative case finding approaches for the identification of foot osteoarthritis (OA) based on the La Trobe radiographic atlas. Methods: This was a cross-sectional study of 533 adults age ≥50 years with foot pain in the past year. Weightbearing dorsoplantar (DP) and lateral radiographs were taken of both feet. The La Trobe radiographic atlas was used to document the presence of osteophytes (OPs) and joint space narrowing (JSN). The prevalence of OA in each joint was documented using both views and features in combination (as recommended in the original atlas), and by using a single view (DP or lateral only) and a single feature (OP or JSN only). Results: Compared to the recommended case definition based on OPs and JSN using both views, a DP-only view identified between 15% and 77% of OA cases, while a lateral-only view identified between 28% and 97% of OA cases. Compared to the recommended case definition of using both features, using only OPs identified between 46% and 94% of OA cases, while using only JSN identified between 19% and 76% of OA cases. Conclusion: Applying the La Trobe radiographic atlas but using only 1 radiograph view (DP or lateral) or 1 feature (OP or JSN) in isolation misses a substantial number of OA cases, and the sensitivity of these approaches varies considerably between different foot joints. These findings indicate that, where possible, the atlas should be administered according to the original description to avoid under-ascertainment of radiographic foot OA.

This “Year in review” presents a selection of research themes and individual studies from the clinical osteoarthritis (OA) field (epidemiology and therapy) and includes noteworthy descriptive, analytical-observational, and intervention studies. The electronic database search for the review was conducted in Medline, Embase and medRxiv (15th April 2020 to 1st April 2021). Following study screening, the following OA-related themes emerged: COVID-19; disease burden; occupational risk; prediction models; cartilage loss and pain; stem cell treatments; novel pharmacotherapy trials; therapy for less well researched OA phenotypes; benefits and challenges of Individual Participant Data (IPD) meta-analyses; patient choice- balancing benefits and harms; OA and comorbidity; and inequalities in OA. Headline study findings included: a longitudinal cohort study demonstrating no evidence for a harmful effect of non-steroidal anti-inflammatory drugs (NSAIDs) in terms of COVID-19 related deaths; a Global Burden of Disease study reporting a 102% increase in crude incidence rate of OA in 2017 compared to 1990; a longitudinal study reporting cartilage thickness loss was associated with only a very small degree of worsening in pain over 2 years; an exploratory analysis of a non-OA randomised controlled trial (RCT) finding reduced risk of total joint replacement with an Interleukin -1β inhibitor (canakinumab); a significant relationship between cumulative disadvantage and clinical outcomes of pain and depression mediated by perceived discrimination in a secondary analysis from a RCT; worsening socioeconomic circumstances were associated with future arthritis diagnosis in an innovative natural experiment (with implications for unique research possibilities arising from the COVID-19 pandemic context).

Summary Objective To identify proximate causes (‘triggers’) of flares in adults with, or at risk of, knee osteoarthritis (OA), estimate their course and consequences, and determine higher risk individuals. Methods In this 13-week web-based case-crossover study adults aged ≥40 years, with or without a recorded diagnosis of knee OA, and no inflammatory arthropathy who self-reported a knee flare completed a questionnaire capturing information on exposure to 21 putative activity-related, psychosocial and environmental triggers (hazard period, ≤72 hours prior). Comparisons were made with identical exposure measurements at four 4-weekly scheduled time points (non-flare control period) using conditional logistic regression. Flare was defined as a sudden onset of worsening signs and symptoms, sustained for ≥24 hours. Flare characteristics, course and consequence were analysed descriptively. Associations between flare frequency and baseline characteristics were estimated using Poisson regression. Results Of 744 recruited participants (mean age (SD) 62.1 (10.2) years; 61% female), 376 reported 568 flares (hazards) and provided 867 valid control period measurements. Thirteen exposures (8 activity-related, 5 psychosocial/environmental) were positively associated with flare onset within 24 hours (strongest odds ratio estimate, knee buckling: 9.06: 95% confidence interval [CI] 5.86, 13.99; weakest, cold/damp weather: 1.45: 95%CI 1.12, 1.87). Median flare duration was 5 days (IQR 3, 8), less common if older (incident rate ratio [IRR] 0.98: 95%CI 0.97, 0.99), more common if female (IRR 1.85: 95%CI 1.43, 2.39). Conclusions Multiple activity-related, psychosocial and environmental exposures are implicated in triggering flares. This evidence can help inform prevention and acute symptom management for patients and clinicians.

Despite current evidence, little is known about the impact of comorbidity burden on invasive management strategies and clinical outcomes in the context of acute coronary syndrome (ACS). All ACS hospitalizations between 2004 and 2014 from the National Inpatient Sample were included, stratified by Elixhauser Comorbidity Score (ECS) and number of Elixhauser Comorbidities (NEC) to compare the receipt of invasive management and clinical outcomes between different ECS and NEC classes to the lowest class of either measure. A total of 6,613,623 records with ACS were included in the analysis. Overall comorbidity burden increased over the 11-year period, with higher comorbidity classes (ECS ≥ 14 and NEC ≥ 5) increasing from 2.1% to 4.6% and 4% to 16%, respectively. Higher ECS and NEC classes negatively correlated with the rates of utilization of coronary angiography (CA) and percutaneous coronary intervention (PCI) (ECS ≥14 vs

Objective: To identify distinct recovery trajectories of acute flares of knee pain and associated participant characteristics. Methods: Data were from the FLARE randomized controlled trial, a multicenter trial in 27 primary care centers in the UK and Netherlands of 3 regimes of oral nonsteroidal antiinflammatory therapy for acute flares of knee pain. Individuals with a history of inflammatory/crystal arthritis, fibromyalgia, and chronic pain syndrome were excluded. Latent class growth analysis was applied to measures of pain intensity repeated over 5 days to identify distinct recovery trajectories. The concurrent courses of interference with activity, stiffness, and swelling for each trajectory group were modelled using generalized estimating equations. Participant age, sex, obesity, and osteoarthritis diagnosis were described for each trajectory group. Results: A total of 449 participants were included (median age 55 years, 41% female, 35% obese, and 42% diagnosed with osteoarthritis). A 6-group cubic model was deemed optimal, with trajectories distinguished by rate of pain reduction and absolute level at final measurement. At the extremes were rapid and near-complete resolution (n = 41, 9%) and persistent, high pain (n = 25, 6%), but most participants showed a reduction and plateau in pain severity within 3–5 days. Within each pain trajectory group, interference with activity, stiffness, and swelling followed the same course as pain. Baseline characteristics did not differ substantially between trajectory groups. Conclusion: Even under a well-adhered to regime of oral nonsteroidal antiinflammatory medication, recovery following acute flares of knee pain is heterogeneous. Our observations that favorable trajectories are apparent within 3–5 days can help to inform treatment decision-making in the patient–health care professional consultation.

Hip and knee osteoarthritis (OA) are leading causes of global disability. Most research to date has focused on the knee, with results often extrapolated to the hip, and this extends to treatment recommendations in clinical guidelines. Extrapolating results from research on knee OA may limit our understanding of disease characteristics specific to hip OA, thereby constraining development and implementation of effective treatments. This review highlights differences between hip and knee OA with respect to prevalence, prognosis, epigenetics, pathophysiology, anatomical and biomechanical factors, clinical presentation, pain and non-surgical treatment recommendations and management. (c) 2021 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.

Objectives To identify distinct foot pain trajectories over seven years and examine their associations with potential prognostic factors. Methods Adults aged ≥50 years registered with four general practices in North Staffordshire, UK were mailed a baseline health survey. Those reporting current or recent foot pain were invited to attend a research assessment clinic. Follow-up was by repeated postal surveys at 18, 36, 54, and 84 months. Distinct trajectories of foot pain were explored using Latent Class Growth Analysis (LCGA). Subsequently, identified trajectories were combined into most and least progressive groups and covariate-adjusted associations with a range of prognostic factors examined. Results Of 560 adults with foot pain attending baseline research clinics, 425 (76%) provided data at baseline and ≥2 follow-up time-points. LCGA for foot pain severity (0-10 Numerical Rating Scale) identified a four-trajectory model: 'mild, improving' (37%); 'moderate, improving' (33%); 'moderate-severe, persistent; (24%); 'severe, persistent' (6%). Compared with individuals in more favourable ('improving') pain trajectories, those in less favourable ('persistent') pain trajectories were more likely to be obese, have routine/manual and intermediate occupations, poorer physical and mental health, catastrophising beliefs, greater foot-specific functional limitation, and self-assessed hallux valgus at baseline. Conclusions Four distinct trajectories of foot pain were identified over a seven-year period, with one-third of individuals classified as having pain that is persistently moderate-severe and severe in intensity. The effect of intervening to target modifiable prognostic factors such as obesity and hallux valgus on long-term outcomes in people with foot pain requires investigation.

The median age for total hip arthroplasty (THA) is over 70 years with the corollary that many individuals have multiple multimorbidities. Despite the predicted improvement in quality of life, THA might be denied even to those with low levels of multimorbidity.ObjectiveTo evaluate how pre-existing levels of multimorbidity influence the likelihood and timing of THA.SettingLongitudinal record linkage study of a UK sample linking their primary care to their secondary care records.ParticipantsA total of 28 025 patients were included, based on the recording of the diagnosis of hip osteoarthritis in a national primary care register, Clinical Practice Research Datalink. Data were extracted from the database on background health and morbidity status using five different constructs: Charlson Comorbidity Index, Electronic Frailty Index and counts of chronic diseases (from list of 17), prescribed medications and number of primary care visits prior to recording of osteoarthritis.Outcome measuresThe record of having received a THA as recorded in the primary care record and the linked secondary care database: Hospital Episode Statistics.Results40% had THA: median follow 10 months (range 1–17 years). Increased multimorbidity was associated with a decreased likelihood of undergoing THA, irrespective of the method of assessing multimorbidity although the impact varied by approach.ConclusionMarkers of pre-existing ill health influence the decision for THA in the elderly with end-stage hip osteoarthritis, although these effects are modest for indices of multimorbidity other than eFI. There is evidence of this influence being present even in people with moderate decrements in their health, despite the balance of benefits to risk in these individuals being positive.

Involving research users in setting priorities for musculoskeletal research is essential to raise awareness of the unmet needs for MSK research, to ensure research outcomes are patient-centred and relevant, have a high likelihood of resulting in patient benefit, reduce research waste and increase research value and impact. In 2018, Versus Arthritis convened an MSK Disorders Research Advisory Group (RAG) which included people with arthritis, health care professionals and researchers in MSK, in order to identify and prioritise research areas with a long-term aim of improving quality and impact of MSK research. On further review, there were few previous prioritisation approaches in this area looking across discovery science to more clinical research, at important research questions which might be common to a range of disorders or approaches incorporating input at all stages of the process by a range of stakeholders including people with arthritis. The group identified that more work to define research priorities in these areas was justified and designed a research priority setting process for MSK disorders. This manuscript documents the methodology that was developed by the group for this process.MethodsFollowing a review, the Child Health and Nutrition Research Initiative (CHNRI) method for research prioritisation was selected as best aligning with the needs of this process. The group agreed on adaptations to the CHNRI approach, context, purpose and remit of the exercise and identified through consensus four priority research Domains: Mechanisms of disease; Diagnosis (including early diagnosis) and measuring the impact of these disorders; Living well with MSK disorders and Successful Translation. From all published CHNRI scoring criteria for generated research avenues or themes of research, the group identified six which were most relevant to this process. To ensure accessibility of the survey and scoring, these were refined to three: Equity (considered cross cutting, not scored but considered throughout the process), Importance (Will research in this area have potential to lead to important new knowledge) and Impact (Might research in this area make a difference). Importance and Impact were to be scored on a scale of 1-10 for each research avenue with equal weighting of these two criteria in the subsequent generation of a total score.Data collectionFollowing ethical approval, an electronic first survey asking for important research uncertainties in the four research domains and any other areas will be distributed to all stakeholders (people with arthritis, researchers in all stages of MSK disorders research, healthcare professionals, industry e.g. pharmaceutical and medical technology companies, research funders, healthcare providers, government policy makers and charities). The next step is to consolidate all the gathered research uncertainties from the first survey into finalised research domains and avenues. Uncertainties will be summarised using deductive thematic analysis and organised into possible themes which will then be considered and refined by each of four appointed subgroups within the RAG. Following group and lay review and refinement of the wording including tests of readability, the second survey including this full list of research avenues will be submitted for ethical approval. The second survey will be completed by the same range of stakeholders as the first survey, both those who previously completed and new respondents. Respondents will be invited to rate each research avenue using the two scoring criteria, with the avenues presented in a random sequence to avoid bias.Analysis PlanAll available data will be analysed, from all respondents completing the survey in full and all partial respondents. For each research avenue, a mean criterion score will be calculated for each of the two criteria from all available survey responses (considering the number of respondents in each case), and then the two mean criterion scores will be summed to create a total score. Response rates and missing data for scoring of avenues will be reported. The primary prioritisation output of this exercise will be to produce a single ranked list of these total scores of research avenues, from highest to lowest. The most highly ranked avenues will be highlighted, for example the top five to top ten overall and from each research domain, with the exact number and nature of this depending on the distribution of the data. Respondent characteristics will be summarised including self-identified stakeholder group, age group, gender and ethnic background, to describe the diversity and representation within the survey respondents as far as possible.Dissemination planFindings will be communicated in a number of formats, both written and spoken, to ensure accessibility to all stakeholders, and will also be used by the charity in internal strategy development. Dissemination will include the submission of a manuscript to a peer-reviewed journal.

Objectives Better indicators from affordable, sustainable data sources are needed to monitor population burden of musculoskeletal conditions. We propose five indicators of musculoskeletal health and assessed if routinely available primary care electronic health records (EHR) can estimate population levels in musculoskeletal consulters. Methods We collected validated patient-reported measures of pain experience, function and health status through a local survey of adults (≥35 years) presenting to English general practices over 12 months for low back pain, shoulder pain, osteoarthritis and other regional musculoskeletal disorders. Using EHR data we derived and validated models for estimating population levels of five self-reported indicators: prevalence of high impact chronic pain, overall musculoskeletal health (based on Musculoskeletal Health Questionnaire), quality of life (based on EuroQoL health utility measure), and prevalence of moderate-to-severe low back pain and moderate-to-severe shoulder pain. We applied models to a national EHR database (Clinical Practice Research Datalink) to obtain national estimates of each indicator for three successive years. Results The optimal models included recorded demographics, deprivation, consultation frequency, analgesic and antidepressant prescriptions, and multimorbidity. Applying models to national EHR, we estimated that 31.9% of adults (≥35 years) presenting with non-inflammatory musculoskeletal disorders in England in 2016/17 experienced high impact chronic pain. Estimated population health levels were worse in women, older aged and those in the most deprived neighbourhoods, and changed little over 3 years. Conclusion National and subnational estimates for a range of subjective indicators of non-inflammatory musculoskeletal health conditions can be obtained using information from routine electronic health records.

Background Patient Reported Outcome Measures (PROM) collected in surveys allow understanding of the health at the population-level. We aimed to test the feasibility of estimating health status as measured by PROMs through ecological prediction models which use local linked survey and primary care electronic health records (EHR) and applying the models to national EHR. Methods 3,710 musculoskeletal consulters registered in 11 general practiced in North Staffordshire, UK and consented the linkage of their survey PROM (high impact pain, (HICP)) with EHR were included in this study. HICP was modelled by EHR predictors covering demographic, lifestyle risk factors, musculoskeletal diagnostic/problems, analgesic prescriptions, comorbidities, and deprivation. Final set of predictors were selected through backward elimination (p > 0.1). Individual-level prediction models (binary logistic regression) were fitted and evaluated in terms of model fit statistics (AIC, BIC, R-square), discrimination (C-statistics) and calibration-slope with internal validation. The final model was cross-mapped to a national UK primary EHR database (Clinical Practice Research Database) to obtain national population estimates of high impact pain. Results The C-statistics and calibration-slope of the final model was 0.77 (95% confidence interval: 0.70-0.79) and 1.00 (0.92-1.08), respectively. The estimated HICP was 51.2% overall among 49,788 UK musculoskeletal consulters and matched hypothesised variation by gender, age, deprivation and geographical regions. Conclusions Estimation of population-level health status as measured by PROM using EHR appears feasible and has potential application in assessing health inequalities. Further independent external validation studies are warranted. Key messages Primary care EHR data could be modelled to predict population-level PROMs.

Introduction Limited data are available on the influence of multimorbidity on the outcomes of total hip replacement for patients with hip osteoarthritis, including the rate of complications and degree of functional benefit. The aim of this study was to investigate the influence of multimorbidity on the outcomes of total hip replacement in the UK. Method A cohort study was performed, with cohort comprised of all patients over 65 years with a diagnosis of hip osteoarthritis recorded in Clinical Practice Research Datalink and receipt of primary total hip replacement recorded in Hospital Episode Statistics Admitted Patient Care. Severity of multimorbidity burden was measured using four different scores (Charlson Comorbidity Index, Electronic Frailty Index, count of drugs prescribed, count of primary care interactions). The outcomes were (i) the risks of total hip replacement, assessed by serious post-operative complications within 90 days (analysed with logistic regression), and (ii) the benefits of surgery, assessed by post-operative Oxford Hip Score (OHS) and EQ-5D quality of life score (analysed with linear regression). Results 6,682 patients were included. The rate of complications was 3.2%. Patients with severe multimorbidity burden were at 1.5 to 2.5 times increased risk of complications than patients without multimorbidity. There was no clinically meaningful difference in the benefits of surgery between patients with and without multimorbidity, irrespective of the method of scoring multimorbidity. Conclusions Even for patients with severe multimorbidity burden, the potential benefits of total hip replacement for osteoarthritis remain substantial, while the increase in risk is relatively small.

Introduction Limited data are available on the influence of multimorbidity on the outcomes of total hip replacement for patients with hip osteoarthritis. Thus, patients with multimorbidity and their clinicians across the UK are making decisions on whether or not to proceed with total hip replacement without clear information available on the potential risks and benefits. It is not known how such patients are currently managed. The aim of this study was to investigate the influence of multimorbidity on the likelihood of receiving total hip replacement in patients with hip osteoarthritis in the UK. Method A cohort study was performed, with cohort comprised of all patients over 65 years with a diagnosis of hip osteoarthritis recorded in Clinical Practice Research Datalink. Severity of multimorbidity burden was measured using four different scores (Charlson Comorbidity Index, Electronic Frailty Index, count of drugs prescribed, count of primary care interactions). The outcome was total hip replacement, evaluated using Kaplan-Meier survival and competing-risk analyses. Results 28,025 patients were included. 10,948 patients underwent total hip replacement. Increased multimorbidity burden was associated with decreased likelihood of undergoing surgery, irrespective of the method of scoring multimorbidity. Electronic Frailty Index had the largest difference between categories. Adjusted hazard ratio (‘severe multimorbidity versus ‘fit’) was 0.34 (95% CI 0.22, 0.51). Conclusions Patients with hip osteoarthritis and concurrent multimorbidity were up to two thirds less likely to undergo total hip replacement. Whether this difference in healthcare management is appropriate depends on to what extent multimorbidity influences the outcomes of total hip replacement.

ObjectivesTo estimate the risk of clinically diagnosed knee osteoarthritis (OA) after different types of knee injuries in young adults.MethodsIn a longitudinal cohort study based on population-based healthcare data from Skåne, Sweden, we included all persons aged 25–34 years in 1998–2007 (n=149 288) with and without diagnoses of knee injuries according to International Classification of Diseases (ICD)-10. We estimated the HR of future diagnosed knee OA in injured and uninjured persons using Cox regression, adjusted for potential confounders. We also explored the impact of type of injury (contusion, fracture, dislocation, meniscal tear, cartilage tear/other injury, collateral ligament tear, cruciate ligament tear and injury to multiple structures) on diagnosed knee OA risk.ResultsWe identified 5247 persons (mean (SD) age 29.4 (2.9) years, 67% men) with a knee injury and 142 825 persons (mean (SD) age 30.2 (3.0) years, 45% men) without. We found an adjusted HR of 5.7 (95% CI 5.0 to 6.6) for diagnosed knee OA in injured compared with uninjured persons during the first 11 years of follow-up and 3.4 (95% CI 2.9 to 4.0) during the following 8 years. The corresponding risk difference (RD) after 19 years of follow-up was 8.1% (95% CI 6.7% to 9.4%). Cruciate ligament injury, meniscal tear and fracture of the tibia plateau/patella were associated with greatest increase in risk (RD of 19.6% (95% CI 13.2% to 25.9%), 10.5% (95% CI 6.4% to 14.7%) and 6.6% (95% CI 1.1% to 12.2%), respectively).ConclusionIn young adults, knee injury increases the risk of future diagnosed knee OA about sixfold with highest risks found after cruciate ligament injury, meniscal tear and intra-articular fracture.

BackgroundDespite absence of evidence of a clinical benefit of arthroscopic partial meniscectomy (APM), many surgeons claim that subgroups of patients benefit from APM.ObjectiveWe developed a prognostic model predicting change in patient-reported outcome 1 year following arthroscopic meniscal surgery to identify such subgroups.MethodsWe included 641 patients (age 48.7 years (SD 13), 56% men) undergoing arthroscopic meniscal surgery from the Knee Arthroscopy Cohort Southern Denmark. 18 preoperative factors identified from literature and/or orthopaedic surgeons (patient demographics, medical history, symptom onset and duration, knee-related symptoms, etc) were combined in a multivariable linear regression model. The outcome was change in Knee injury and Osteoarthritis Outcome Score (KOOS4) (average score of 4 of 5 KOOS subscales excluding the activities of daily living subscale) from presurgery to 52 weeks after surgery. A positive KOOS4change score constitutes improvement. Prognostic performance was assessed using R2statistics and calibration plots and was internally validated by adjusting for optimism using 1000 bootstrap samples.ResultsPatients improved on average 18.6 (SD 19.7, range −38.0 to 87.8) in KOOS4. The strongest prognostic factors for improvement were (1) no previous meniscal surgery on index knee and (2) more severe preoperative knee-related symptoms. The model’s overall predictive performance was low (apparent R2=0.162, optimism adjusted R2=0.080) and it showed poor calibration (calibration-in-the-large=0.205, calibration slope=0.772).ConclusionDespite combining a large number of preoperative factors presumed clinically relevant, change in patient-reported outcome 1 year following meniscal surgery was not predictable. This essentially quashes the existence of ‘subgroups’ with certain characteristics having a particularly favourable outcome after meniscal surgery.Trial registration numberNCT01871272.

BackgroundAcute flares in people with osteoarthritis (OA) are poorly understood. There is uncertainty around the nature of flares, their impact, and how these are managed.AimTo explore understandings and experiences of flares in people with knee OA, and to describe self-management and help-seeking strategies.Design & settingQualitative interview study of people with knee OA in England.MethodSemi-structured interviews were undertaken with 15 people with knee OA. Thematic analysis was applied using constant comparison methods.ResultsThe following four main themes were identified: experiencing pain; consequences of acute pain; predicting and avoiding acute pain; and response to acute pain. People with OA described minor episodes that were frequent, fleeting, occurred during everyday activity, had minimal impact, and were generally predictable. This contrasted with severe episodes that were infrequent, had greater impact, and were less likely to be predictable. The latter generally led to feelings of low confidence, vulnerability, and of being a burden. The term ‘flare’ was often used to describe the severe events but this was applied inconsistently and some would describe a flare as any increase in pain. Participants used numerous self-management strategies but tended to seek help when these had been exhausted, their symptoms led to emotional distress, disturbed sleep, or pain experience worse than usual. Previous experiences shaped whether people sought help and who they sought help from.ConclusionSevere episodes of pain are likely to be synonymous with flares. Developing a common language about flares will allow a shared understanding of these events, early identification, and appropriate management.

Aim To identify existing comorbidity measures and summarise their association with acute coronary syndrome (ACS) outcomes. Methods We searched published studies from MEDLINE (OVIDSP) and EMBASE from inception to March 2021, studies of the pre-specified conference proceedings from Web of Science since May 2017, and studies included in any relevant systematic reviews. Studies that reported no comorbidity measures, no association of comorbid burden with ACS outcomes, or only used a comorbidity measure as a confounder without further information were excluded. After independent screening by three reviewers, data extraction and risk of bias assessment of each included study was undertaken. Results were narratively synthesised. Results Of 4166 potentially eligible studies identified, 12 (combined n=6,885,982 participants) were included. Most studies had a high risk of bias at quality assessment. Six different types of comorbidity measures were identified with the Charlson comorbidity index (CCI) the most widely used measure among studies. Overall, the greater the comorbid burden or the higher comorbidity scores recorded, the greater was the association with the risk of mortality. Conclusion The review summarised different comorbidity measures and reported that higher comorbidity scores were associated with worse ACS outcomes. The CCI is the most widely measure of comorbid burden and shows additive value to clinical risk scores in use.

Objective To compare the performance of risk adjustment models using the Elixhauser and Charlson comorbidity scores in predicting in-hospital outcomes of ACS patients from a nationwide administrative database. Study Design and Setting All hospitalizations for ACS in the United States between 2004 and 2014 (n = 7,201,900) were retrospectively analyzed. We used ECS and CCI score based on ICD-9 codes to define comorbidity variables. Logistic regression models were fitted to three in-hospital outcomes, including mortality, Major Acute Cardiovascular & Cerebrovascular Events (MACCE) and bleeding. The prognostic values of ECS and CCI after adjusting for known confounders, were compared using the C-statistic, Akaike information criterion (AIC), and Bayesian information criterion (BIC). Results The statistical performance of models predicting all in-hospital outcomes demonstrated that the ECS had superior prognostic value compared to the CCI, with higher C-statistics and lower AIC and BIC values associated with the former. Conclusion This is the first study that compared the prognostic value of the ECS and CCI scores in predicting multiple ACS outcomes, based on their scoring systems. Better discrimination and goodness of fit was achieved with the Elixhauser method across all in-hospital outcomes studied.

Objective Hallux valgus is a common and disabling condition. The objective of this study was to identify factors associated with hallux valgus incidence and progression. Methods Participants were from a population-based prospective cohort study, the Clinical Assessment Study of the Foot. All adults aged ≥50 years registered with four general practices in North Staffordshire, UK were invited to take part in a postal survey at baseline and at 7-year follow-up which included health questionnaires and self-assessment of hallux valgus using line drawings. Results Complete baseline and follow-up data were available for 1,482 participants (739 women and 743 men, mean [standard deviation] age 62.9 [8.1] years), of whom 450 (30.4%) had hallux valgus in at least one foot at baseline. Incident hallux valgus was identified in 207 (20.1%) participants (349 [15.4%] feet) and was associated with baseline age, poorer physical health, foot pain and wearing shoes with a very narrow toe-box shape between the age of 20 and 29 years. Hallux valgus progression was identified in 497 (33.6%) participants (719 [24.3%] feet) but was not associated with any baseline factors. Conclusion Incident hallux valgus develops in one in five adults aged ≥50 years over a 7-year period and is related to age, poorer physical health, foot pain and previous use of constrictive footwear. Progression occurs in one in three adults. These findings suggest that changes in first metatarsophalangeal joint alignment may still occur beyond the age of 50 years.

Purpose: The burden of osteoarthritis (OA) is often greater among disadvantaged people and communities, prompting calls for more attention to equity-focussed research and policy. A specific concern is whether healthcare interventions may inadvertently widen health inequalities. OA management programmes (OAMP) have emerged in the past decade in a major international effort to improve provision of core non-surgical care for people with OA. Recent studies have focussed on equity of access. We address a complementary issue: having gained access, do people from socially disadvantaged groups have poorer outcomes than their advantaged counterparts, and if so, what might determine this?\ud \ud Methods: The study population was consecutive adults with knee OA attending the 8-week GLA:D® supervised exercise and education programme in Denmark between Oct 2014-Feb 2018. We defined a ‘multiple social disadvantage’ group based on primary/secondary school education and being either born outside Denmark or not having Danish citizenship. Their outcomes were compared with those of native Danish citizens with higher education. Outcomes of interest were pain intensity (0-100 VAS), KOOS Quality of Life subscale (QOL 0-100), EQ-5D-5L health utility (-0.624-1.0) at 3 and 12 months. Missing data were imputed using multiple imputation with chained equations. We used Coarsened Exact Matching (CEM) to restrict group comparisons to areas of common support, i.e. sufficient overlap on key prognostic factors (age, sex, body mass index, baseline value of the outcome measure of interest). We then used Entropy Balancing to sequentially control for differences between disadvantaged and advantaged groups in: (1) baseline value of the outcomes of interest (2) type of treatment centre, enrollment year (3) age, sex (4) BMI, previous knee injury, previous knee surgery (5) no. of selected comorbidities, no. of other non-knee pain sites (6) self-efficacy score, self-reported presence of depression (7) previous/current tailored exercise advice, weight loss counselling, analgesia/natural remedies (8) attendance at GLA:D® education and exercise sessions. Mean differences in outcomes between disadvantaged and advantaged groups were then estimated by weighted linear regression without balancing and then with entropy balancing weights from steps 1-8.\ud \ud Results: Of 18,448 eligible participants, 250 (1.4%) were classed as disadvantaged. Compared with advantaged participants, they were younger, less likely to have attended GLA:D® in a private physiotherapy clinic, reported more comorbidity, pain sites, depression, lower self-efficacy, and lower attendance on GLA:D® sessions. Both groups showed overall improvements over baseline in mean pain VAS, KOOS QOL and EQ5D scores at 3 months, typically maintained at 12 months. Before covariate balancing, disadvantaged participants had substantially worse scores than advantaged participants on each measure at both follow-up points (e.g. crude between-group mean differences (95%CI) in pain VAS at 12 months: 8.6 (4.5, 12.6) respectively: Table 1). Balancing for differences on baseline score, comorbidity, self-efficacy, and depression had the greatest effect on reducing differences in outcomes.\ud \ud Conclusions: Both disadvantaged and advantaged adults with knee OA reported improvements in key outcomes up to 12 months after OAMP attendance. However, compared with more advantaged adults, disadvantaged adults typically began the OAMP with more severe pain and poorer quality of life. This gap in outcomes was not reduced following OAMP attendance: for generic health-related quality of life in particular the gap widened slightly. Low self-efficacy, depression and other comorbidities may be potential determinants. Our analysis is of observed outcomes in a relatively small group with multiple disadvantage attending one OAMP. We encourage further work in other settings and groups. If confirmed, our findings suggest that while improving access to OAMPs for socially disadvantaged people with OA is important, additional actions may be needed to reduce outcome inequalities.

BackgroundBrace effectiveness for knee osteoarthritis (OA) remains unclear and international guidelines offer conflicting recommendations. Our trial will determine the clinical and cost-effectiveness of adding knee bracing (matched to patients’ clinical and radiographic presentation and with adherence support) to a package of advice, written information and exercise instruction delivered by physiotherapists.Methods and analysisA multicentre, pragmatic, two-parallel group, single-blind, superiority, randomised controlled trial with internal pilot and nested qualitative study. 434 eligible participants with symptomatic knee OA identified from general practice, physiotherapy referrals and self-referral will be randomised 1:1 to advice, written information and exercise instruction and knee brace versus advice, written information and exercise instruction alone. The primary analysis will be intention-to-treat comparing treatment arms on the primary outcome (Knee Osteoarthritis Outcomes Score (KOOS)-5) (composite knee score) at the primary endpoint (6 months) adjusted for prespecified covariates. Secondary analysis of KOOS subscales (pain, other symptoms, activities of daily living, function in sport and recreation, knee-related quality of life), self-reported pain, instability (buckling), treatment response, physical activity, social participation, self-efficacy and treatment acceptability will occur at 3, 6, and 12 months postrandomisation. Analysis of covariance and logistic regression will model continuous and dichotomous outcomes, respectively. Treatment effect estimates will be presented as mean differences or ORs with 95% CIs. Economic evaluation will estimate cost-effectiveness. Semistructured interviews to explore acceptability and experiences of trial interventions will be conducted with participants and physiotherapists delivering interventions.Ethics and disseminationNorth West Preston Research Ethics Committee, the Health Research Authority and Health and Care Research in Wales approved the study (REC Reference: 19/NW/0183; IRAS Reference: 247370). This protocol has been coproduced with stakeholders including patients and public. Findings will be disseminated to patients and a range of stakeholders.Trial registration numberISRCTN28555470.

We read with great interest the editorial on foot osteoarthritis (OA) by Golightly and Gates (1). Foot OA is prevalent but neglected compared with other commonly affected sites such as the knee and hand (2), hence such a high-profile statement of need for foot OA is long overdue.

Objectives To produce national and regional estimates and trends for gabapentinoid–opioid co-prescribing rates in patients with OA, both in absolute terms and relative to matched controls without OA. Methods Using the UK Clinical Practice Research Datalink database we first constructed age–sex–practice–date 1:1 matched cohorts of patients aged ≥40 years with and without a new diagnosis of OA between 1995–2017 and estimated the relative incidence of a first gabapentinoid prescription. Incident gabapentinoid users in both cohorts were followed to estimate and compare the event rate of gabapentinoid–opioid co-prescription (prescription from both classes within the same 28-day window). Results The incidence of first gabapentinoid prescription was 3-fold higher in patients with OA than in matched controls [n = 215 357; incidence rate ratio (IRR) 2.93; 95% CI: 2.87, 3.00]. Among incident gabapentinoid users with OA (n = 27 374, median follow-up 3.9 years) the event rate of gabapentinoid–opioid co-prescription was 4.03 (4.02–4.05) per person-year. The rate was higher in OA patients classed as long-term gabapentinoid users (6.24; 6.22–6.26). These rates were significantly higher than in incident gabapentinoid users without OA [adjusted-IRR: 1.29 (1.28–1.30)]. This elevated risk was observed across age, sex, geographic regions, and calendar years, when restricted to strong opioids and to long-term gabapentinoid users, and when co-prescription was defined as within 14 days and same-day prescribing. Conclusions Patients with OA not only have a higher risk of being prescribed a gabapentinoid but, once prescribed a gabapentinoid, are also at greater risk of opioid co-prescription. Strict restriction of gabapentinoid–opioid co-prescription, and improved access to, and uptake of, effective non-pharmacological and surgical alternatives for OA are required.

Summary This personal choice of research themes and highlights from within the past year (1 May 2019 to 14 April 2020) spans descriptive, analytical-observational, and intervention studies. Descriptive estimates of the burden of osteoarthritis continue to underscore its position as a leading cause of disability worldwide, but whose burden is often felt greatest among disadvantaged and marginalised communities. Many of the major drivers of that burden are known but epidemiological studies continue the important work of elaborating on their timing, dose, specificity, and reversibility and placing them within an appropriate multi-level framework. A similar process of elaboration is seen also in studies (re-)estimating the relative benefits and risks of existing interventions, in some cases helping to identify low-value care, unwarranted variation, and initiating processes of deprescribing and decommissioning. Such research need not engender therapeutic nihilism. Our review closes by highlighting some emerging evidence on the efficacy and safety of novel therapeutic interventions and with a selective roll-call of methodological and meta-research in OA illustrating the continued commitment to improving research quality.

Background Foot pain is common and disabling in older adults however little is known about its course. The objective of this study was to identify foot pain trajectories over seven years and examine the associations between progressive symptom trajectories and potential prognostic factors. Methods All adults aged ≥50 years registered with four general practices in North Staffordshire, UK were mailed a health survey at baseline. Those reporting foot pain in the previous 12 months were invited to attend a research clinic that included a standardised interview, physical examination, and plain radiographs of the feet. Follow-up was by repeated postal surveys at 18 months, three years, 54 months, and seven years. Trajectories of repeated measures of foot pain severity in the previous month (10-point numerical rating scale) were identified using Latent Class Growth Analysis (LCGA). Logistic regression was undertaken to explore the relationship between these trajectories and both person-level and foot-level prognostic factors adjusted for covariates (age, gender, and body mass index). Results Of 560 adults with foot pain attending baseline research clinics, 425 (76%) provided data at baseline and ≥two follow-up time-points and were included in the analysis. The optimum LGCA model for foot pain severity was a 4-class model with the following trajectories: mild improving pain (n = 109, 26%); moderate improving pain (n = 179, 42%); moderate persistent pain (n = 122, 29%); severe persistent pain (n = 15, 4%). Compared with individuals with mild/moderate improving pain trajectories, those with moderate/severe persistent pain trajectories over 7 years did not differ significantly by age, sex, foot posture or radiographic foot OA phenotype at baseline, but were more likely to be overweight/obese. After adjustment for covariates, these less favourable long-term trajectories were associated with lower socioeconomic position, poorer physical and mental health, catastrophising, greater foot-specific functional limitation (Manchester Foot Pain and Disability Index), and self-reported hallux valgus at baseline (Table 1). Conclusion Over a 7-year period, one-third of individuals had persistent moderate to severe pain. Targeting interventions to modifiable prognostic factors such as obesity and hallux valgus may have the potential to improve long-term outcomes in people with foot pain. Disclosures M. Marshall None. M. Blagojevic-Bucknall None. T. Rathod-Mistry None. M.J. Thomas None. J.J. Edwards Other; JJE is part of The Keele Academic General Practice which has received funding from Bristol-Myers Squibb to develop and evaluate a quality improvement tool in anticoagulation. G. Peat None. H.B. Menz None. E. Roddy None.

Background Evidence of the effectiveness of intra-articular corticosteroid injection for hip osteoarthritis (OA) is limited. The HIT trial compared the clinical and cost-effectiveness of an ultrasound-guided intra-articular hip injection (USGI) of 40mg triamcinolone acetonide and 4ml 1% lidocaine hydrochloride combined with best current treatment (BCT) with (i) BCT alone (primary objective) and (ii) an USGI of 5ml 1% lidocaine only combined with BCT (EudraCT:2014-003412-37). Methods This was a pragmatic, three-parallel arm, single-blind, randomised controlled trial in adults with moderate-severe painful hip OA recruited from community musculoskeletal services and primary care. Participants were randomised equally to: (1) BCT alone, (2) BCT plus USGI triamcinolone/lidocaine, or (3) BCT plus USGI lidocaine only. Outcomes were collected postally at 2 weeks, 2, 4 and 6 months. The primary outcome was self-reported current hip pain intensity (0-10 numeric rating scale (NRS)) over 6 months (repeated measures analysis). Secondary outcomes included function (WOMAC), and, for cost-utility analysis, general health (EQ-5D-5L) and healthcare utilisation. 204 participants were required to detect a minimum difference of 1 point in mean pain NRS score between arms (1) and (2) with 80% power (5% two-tailed significance level, 15% loss to follow-up). Analysis was by intention-to-treat. Results 199 participants were recruited (43% male, mean age 63 years), 67 to arm (1) and 66 each to arms (2) and (3). Primary outcome completion rates were 95% at 2 weeks, 94% at 2 months, 90% at 4 months, and 89% at 6 months. Greater mean improvement in hip pain intensity (0-10 NRS) over 6 months was seen with BCT plus USGI triamcinolone/lidocaine compared with BCT alone: -1.43 (95%CI -2.15,-0.72). Greater mean improvement in pain intensity was seen at 2 weeks (-3.17; -4.06,-2.28) and 2 months (-1.81;-2.71,-0.92), but not at 4 (-0.86;-1.78,0.05) or 6 months (0.12; -0.80,1.04). Participants treated with BCT plus USGI triamcinolone/lidocaine compared with BCT alone had greater mean improvement in function (WOMAC-F -5.47;(-9.41,-1.53)) over 6 months. There was no statistically significant difference in hip pain intensity over 6 months between BCT plus USGI triamcinolone/lidocaine compared with BCT plus USGI lidocaine (-0.52;-1.21,0.18). There was one possible treatment-related serious adverse event: a participant with no signs of infection at randomisation died from endocarditis four months after USGI triamcinolone/lidocaine. BCT plus USGI triamcinolone/lidocaine was less costly (mean cost difference per participant £-161.59) and associated with significantly higher quality-adjusted life-years (QALYs) than BCT only over 6 months (mean difference 0.0477 (0.0257,0.0699). Conclusion USGI triamcinolone/lidocaine plus BCT leads to greater improvements in pain and function over 6 months in adults with hip OA than BCT alone, and was highly cost-effective. There was no significant difference in hip pain intensity between the groups receiving USGI triamcinolone/lidocaine and USGI lidocaine only, raising the possibility of a degree of placebo effect. Disclosures Z. Paskins None. K. Bromley None. M. Lewis None. G. Hughes None. E. Hughes None. A. Cherrington None. A. Hall None. M. Holden None. R. Oppong None. J. Kigozi None. K. Stevenson None. A. Menon None. P. Roberts None. G. Peat None. C. Jinks None. N.E. Foster None. C.D. Mallen None. E. Roddy None.

Background Hallux valgus (HV) is a common disabling condition affecting 36% of adults aged 65 years and over. Identifying whether the severity of the deformity alters weight-bearing patterns during walking may assist clinicians optimize offloading interventions. Therefore, we examined how plantar pressure distributions during walking are affected by HV severity. Methods Plantar pressures and maximum forces in ten regions of the foot were obtained from 120 participants (40 men, 80 women) aged ≥50 years using a pressure platform (RSscan® International, Olen, Belgium). HV severity was documented using a validated line-drawing instrument with participants separated into four groups: none (n = 30), mild (n = 30), moderate (n = 30) and severe (n = 30). Pressure and force values were compared across HV severity, stratified by the presence or absence of great toe pain. Results Participants with severe HV were more likely to have great toe pain. More severe HV was associated with significant reductions in peak pressure and maximum force under the hallux but not at other sites of the foot. This association appeared strongest in those reporting great toe pain. Conclusions Greater HV severity is associated with great toe pain and reduced loading under the hallux when walking. These observed changes in plantar pressure and maximum force may reflect a pain avoidance mechanism.

Background The concept of osteoarthritis (OA) heterogeneity is evolving and gaining renewed interest. According to this concept, distinct subtypes of OA need to be defined that will likely require recognition in research design and different approaches to clinical management. Although seemingly plausible, a wide range of views exist on how best to operationalize this concept. The current project aimed to provide consensus-based definitions and recommendations that together create a framework for conducting and reporting OA phenotype research. Methods A panel of 25 members with expertise in OA phenotype research was composed. First, panel members participated in an online Delphi exercise to provide a number of basic definitions and statements relating to OA phenotypes and OA phenotype research. Second, panel members provided input on a set of recommendations for reporting on OA phenotype studies. Results Four Delphi rounds were required to achieve sufficient agreement on 11 definitions and statements. OA phenotypes were defined as subtypes of OA that share distinct underlying pathobiological and pain mechanisms and their structural and functional consequences. Reporting recommendations pertaining to the study characteristics, study population, data collection, statistical analysis, and appraisal of OA phenotype studies were provided. Conclusions This study provides a number of consensus-based definitions and recommendations relating to OA phenotypes. The resulting framework is intended to facilitate research on OA phenotypes and increase combined efforts to develop effective OA phenotype classification. Success in this endeavor will hopefully translate into more effective, differentiated OA management that will benefit a multitude of OA patients.

Patients presenting with acute coronary syndrome (ACS) are frequently co-morbid. However, there is limited data on how co-morbidity burden impacts their receipt of invasive management and subsequent outcomes. We analyzed all patients with a discharge diagnosis of ACS from the National Inpatient Sample (2004 to 2014), stratified by Charlson Co-morbidity Index (CCI) into 4 classes (CCI 0, 1, 2, and ≥3). Regression analyses were performed to examine associations between co-morbidity burden and receipt of invasive intervention and in-hospital clinical outcomes. Of all 6,613,623 ACS patients analyzed, the prevalence of patients with severe co-morbidity (CCI ≥3) increased from 10.8% (2004) to 18.1% (2014). CCI class negatively correlated with receipt of invasive management, with CCI ≥3 group being the least likely to receive coronary angiography and percutaneous coronary intervention (odds ratio (OR) 0.42 95% confidence interval [CI] 0.41 to 0.43 and OR 0.47, 95% CI 0.46 to 0.48, respectively). CCI class was independently associated with an increased risk of mortality and complications, especially CCI ≥3 that was associated with significantly increased odds of Major Acute Cardiovascular & Cerebrovascular Events (OR 1.70, 95% CI 1.66 to 1.75), mortality (OR 1.74, 95% CI 1.68 to 1.79), acute ischemic stroke (OR 2.35, 95% CI 2.23 to 2.46), and major bleeding (OR 1.64, 95% CI 1.59 to 1.69). Co-morbidity burden has significantly increased amongst those presenting with ACS over an 11-year period and correlates with reduced likelihood of receipt of invasive management and increased odds of mortality and adverse outcomes. In conclusion, objective assessment of co-morbidities using CCI score identifies high-risk ACS patients in whom targeted risk reduction strategies may reduce their inherent risk of mortality and complications.

In this brief report, we used data from a series of three related cohorts on pain and osteoarthritis (OA) of the knee, hand and foot, which were conducted in North Staffordshire, England. We used a common approach for sampling, data collection and coding, to estimate the relative prevalence of 10 different symptomatic radiographic OA subtypes in the knee, hand and foot and to compare their association with age, sex, socioeconomic position and body mass index. Overall, symptomatic hand OA was more common than knee or foot OA (22.4% vs 17.4% vs 16.5%), due mainly to the high prevalence of nodal interphalangeal joint OA among women. The first carpometacarpal joint OA was the most frequent subtype, with patellofemoral, tibiofemoral, (nodal) interphalangeal and midfoot OA also common. Of the risk factors examined, the greatest differences between subtypes appeared to be their associations with sex and obesity: sex differences were noticeably greater for all forms of hand OA except non-nodal interphalangeal joint OA, while obesity appeared most strongly associated with forms of knee OA. The prevalence of all subtypes was higher among older ages, and among those with lower educational attainment.

Background Osteoarthritis (OA) is a leading cause of persistent pain and disability. Traditionally viewed as a slowly progressive disease, the impact of symptom variability on prognosis remains unclear. ‘Acute-on-chronic’ episodes are a well-recognised feature of many long-term conditions but only recently formally described in OA. This study aimed to develop a web-based data collection platform and establish key methodological design parameters, to develop a larger community-based study investigating acute flares of knee OA in England. Methods The study is a 9-week feasibility and pilot web-based observational case-crossover study. Adults aged ≥ 40 years registered with two general practices who had consulted their general practitioner for knee pain/OA in the last 2 years were recruited. Participants completed a baseline questionnaire and scheduled (control-period) questionnaires at follow-up weeks 1, 5, and 9. Participants were invited to self-declare via the website on any occasion they experienced a knee pain flare-up lasting ≥ 24 h. Upon notification, an event-driven (case-period) questionnaire comparable to the scheduled questionnaires was completed and daily measurements on the course and consequences were taken until resolution. A sub-study of 10 participants logged daily pain measurements. The analysis estimated key parameters including recruitment (selective non-participation, eligibility, consent), retention, and flare-up capture processes. Questionnaire completeness and website usability were evaluated. Results Of 442 patients invited, 14 completed baseline questionnaires. Eligibility rate was 26.9% (95% CI 19.3, 36.2), consent rate 53.6% (35.8, 70.5), and overall recruitment rate 3.2% (1.9, 5.2). Compared to those mailed, baseline responders were more likely to be male and ≥ 65 years, as were those reporting ≥ 1 flare-up. Eleven scheduled questionnaires were completed (mean response 35%). Although seven participants (50%) self-declared 11 flare-ups, only one event-driven questionnaire was completed and three participants contributed daily flare measurement for four flares. Missing data was ≤ 3.7% across completed baseline, scheduled, and event-driven questionnaires. Aspects of website usability require minor refinement. Conclusions Recruitment was not feasible with the current strategy. An evaluation of processes has suggested several substantial changes in design that may enhance recruitment, retention, and data quality in a future full-scale study.

Objectives\ud To examine associations between plantar calcaneal spurs, plantar fascia thickening and plantar heel pain (PHP), and to determine whether tenderness on palpation of the heel differentiates between these presentations. \ud \ud Methods\ud Adults aged ≥50 years registered with four general practices were mailed a Health Survey. Responders reporting foot pain within the last 12 months underwent a detailed clinical assessment. PHP in the past month was documented using a foot manikin. Plantar calcaneal spurs were identified from weight-bearing lateral radiographs and plantar fascia thickening (defined as >4mm) from ultrasound. Tenderness on palpation of the plantar fascia insertion was documented. Associations between these factors and PHP were explored using generalised estimating equations.\ud \ud Results\ud Clinical and radiographic data were available from 530 participants (296 women, mean [SD] age 64.9 [8.4] years), 117 (22.1%) of whom reported PHP. Plantar calcaneal spurs and plantar fascia thickening were identified in 281 (26.5%) and 501 (47.3%) feet, respectively, but frequently coexisted (n=217, 20.4%). Isolated plantar calcaneal spurs were rare (n=64, 6.0%). Participants with PHP were more likely to have a combination of these features compared to those without PHP (odds ratio 2.16, 95% confidence interval 1.24–3.77, p=0.007). Tenderness on palpation of the heel was not associated with plantar calcaneal spurs or plantar fascia thickening, either in isolation or in combination, in those with PHP. \ud \ud Conclusion\ud Plantar calcaneal spurs and plantar fascial thickening are associated with PHP, but frequently coexist. Tenderness on palpation of the heel does not appear to differentiate between clinical presentations of PHP.

Dahai Yu, Kelvin P Jordan, George Peat Arthritis Research UK Primary Care Centre, Research Institute for Primary Care & Health Sciences, Keele University, Keele, Newcastle, UK Purpose: Primary care electronic health records are increasingly used to estimate the occurrence of osteoarthritis (OA). We aimed to estimate the extent and trend over time of underrecording of severe OA patients in UK primary care electronic health records using first primary total hip and knee replacements (THR/TKR) – >90% of which are performed for OA – as the reference population.Patients and methods: We identified patients with a first primary THR or TKR recorded in the UK Clinical Practice Research Datalink between 2000 and 2015. We then searched for a diagnostic/problem code for OA up to 10 years prior to THR/TKR using 3 definitions: “diagnosed OA (joint-specific),” “diagnosed OA (any joint),” “clinical OA” (diagnosed OA or relevant peripheral joint pain symptom code).Results: Among 34,299 THR patients identified, 28.1%, 53.4%, and 74.4% had a prior record of diagnosed OA (hip), diagnosed OA (any), and clinical OA, respectively. Among 47,588 TKR patients, the corresponding figures were, 25.5% (diagnosed OA [knee]), 43.7%, and 74.8%. In the UK Clinical Practice Research Datalink, the proportion of patients with prior recorded OA decreased between 2000 and 2015.Conclusion: An increasing trend of underrecording of OA or joint pain among patients with THR or TKR (severe OA patients) between 2000 and 2015 was identified. An underestimate health care demand could be derived based on consultation incidence and prevalence of OA from electronic health record data that relies on osteoarthritis diagnostic codes. Further studies are warranted to investigate the validity of OA or joint pain recorded in primary care settings, which might be used to correct the consultation incidence and prevalence of OA. Keywords: joint pain, total knee replacement, total hip replacement, sensitivity

Objective: To determine whether selected metabolic factors are associated with greater amounts of radiographic hand osteoarthritis (OA) incidence and progression. Methods: The study identified 706 adults, aged 50–69 years, with hand pain and hand radiographs at baseline, from two population-based cohorts. Metabolic factors (body mass index, hypertension, dyslipidaemia, and diabetes) were ascertained at baseline by direct measurement and medical records. Analyses were undertaken following multiple imputation of missing data, and in complete cases (sensitivity analyses). Multivariable regression models estimated associations between metabolic factors and two measures of radiographic change at 7 years for all participants, individuals free of baseline radiographic OA, and in baseline hand OA subsets. Estimates were adjusted for baseline values and other covariates. Results: The most consistent and strong associations observed were between the presence of diabetes and the amount of radiographic progression in individuals with nodal OA [adjusted mean differences in Kellgren–Lawrence summed score of 4.50 (−0.26, 9.25)], generalized OA [3.27 (−2.89, 9.42)], and erosive OA [3.05 (−13.56, 19.67)]. The remaining associations were generally weak or inconsistent, although numbers were limited for analyses of incident radiographic OA and erosive OA in particular. Conclusion: Overall metabolic risk factors were not independently or collectively associated with greater amounts of radiographic hand OA incidence or progression over 7 years, but diabetes was associated with radiographic progression in nodal, and possibly generalized and erosive OA. Diabetes has previously been associated with prevalent but not incident hand OA. Further investigation in hand OA subsets using objective measures accounting for disease duration and control is warranted.

Total hip arthroplasty (THA) surgery for elderly people with multimorbidity increases the risk of serious health hazards including mortality. Whether such background morbidity reduces the clinical benefit is less clear.ObjectiveTo evaluate how pre-existing health status, using multiple approaches, influences risks of, and quality of life benefits from, THA.SettingLongitudinal record linkage study of a UK sample linking their primary care to their secondary care records.ParticipantsA total of 6682 patients were included, based on the recording of the diagnosis of hip osteoarthritis in a national primary care register and the recording of the receipt of THA in a national secondary care register.Data were extracted from the primary care register on background health and morbidity status using five different constructs: Charlson Comorbidity Index, Electronic Frailty Index (eFI) and counts of comorbidity disorders (from list of 17), prescribed medications and number of primary care visits prior to recording of THA.Outcome measures(1) Postoperative complications and mortality; (2) postoperative hip pain and function using the Oxford Hip Score (OHS) and health-related quality of life using the EuroQoL (EQ)-5D score.ResultsPerioperative complication rate was 3.2% and mortality was 0.9%, both increased with worse preoperative health status although this relationship varied depending on the morbidity construct: the eFI showing the strongest relationship but number of visits having no predictive value. By contrast, the benefits were not reduced in those with worse preoperative health, and improvement in both OHS and EQ-5D was observed in all the morbidity categories.ConclusionsIndependent of preoperative morbidity, THA leads to similar substantial improvements in quality of life. These are offset by an increase in medical complications in some subgroups of patients with high morbidity, depending on the definition used. For most elderly people, their other health disorders should not be a barrier for THA.

Background Selection bias is a concern when designing cluster randomised controlled trials (c-RCT). Despite addressing potential issues at the design stage, bias cannot always be eradicated from a trial design. The application of bias analysis presents an important step forward in evaluating whether trial findings are credible. The aim of this paper is to give an example of the technique to quantify potential selection bias in c-RCTs. Methods This analysis uses data from the Primary care Osteoarthritis Screening Trial (POST). The primary aim of this trial was to test whether screening for anxiety and depression, and providing appropriate care for patients consulting their GP with osteoarthritis would improve clinical outcomes. Quantitative bias analysis is a seldom-used technique that can quantify types of bias present in studies. Due to lack of information on the selection probability, probabilistic bias analysis with a range of triangular distributions was also used, applied at all three follow-up time points; 3, 6, and 12 months post consultation. A simple bias analysis was also applied to the study. Results Worse pain outcomes were observed among intervention participants than control participants (crude odds ratio at 3, 6, and 12 months: 1.30 (95% CI 1.01, 1.67), 1.39 (1.07, 1.80), and 1.17 (95% CI 0.90, 1.53), respectively). Probabilistic bias analysis suggested that the observed effect became statistically non-significant if the selection probability ratio was between 1.2 and 1.4. Selection probability ratios of > 1.8 were needed to mask a statistically significant benefit of the intervention. Conclusions The use of probabilistic bias analysis in this c-RCT suggested that worse outcomes observed in the intervention arm could plausibly be attributed to selection bias. A very large degree of selection of bias was needed to mask a beneficial effect of intervention making this interpretation less plausible.

Objective\ud To assess whether foot and/or ankle symptoms are associated with an increased risk of worsening of knee pain and radiographic change in people with knee osteoarthritis (OA).\ud \ud Methods\ud The presence and laterality of foot/ankle symptoms were recorded at baseline in 1368 participants from the Osteoarthritis Initiative (OAI) with symptomatic radiographic knee OA. Knee pain severity (measured using the Western Ontario and McMaster Universities Osteoarthritis Index pain subscale) and minimum medial tibiofemoral joint space (minJSW) width measured on X-ray were assessed yearly over the subsequent 4 years. Associations between foot/ankle symptoms and worsening of (1) knee pain, and (2) both knee pain and minJSW (i.e., symptomatic radiographic knee OA) were assessed using logistic regression.\ud \ud Results\ud Foot/ankle symptoms in either foot/ankle significantly increased the odds of knee pain worsening (adjusted OR 1.54, 95% CI 1.25 to 1.91). Laterality analysis showed ipsilateral (adjusted OR 1.50, 95% CI 1.07 to 2.10), contralateral (adjusted OR 1.44, 95% CI 1.02 to 2.06) and bilateral foot/ankle symptoms (adjusted OR 1.61, 95% CI 1.22 to 2.13) were all associated with knee pain worsening in the follow up period. There was no association between foot/ankle symptoms and worsening of symptomatic radiographic knee OA.\ud \ud Conclusion\ud The presence of foot/ankle symptoms in people with symptomatic radiographic knee OA was associated with increased risk of knee pain worsening, but not worsening of symptomatic radiographic knee OA, over the subsequent 4 years. Future studies should investigate whether treatment of foot/ankle symptoms reduces the risk of knee pain worsening in people with knee OA.

Objective\ud To investigate whether foot and/or ankle symptoms increase the risk of developing (1) knee symptoms and (2) symptomatic radiographic knee osteoarthritis (OA).\ud \ud Design\ud 1020 Osteoarthritis Initiative (OAI) participants who were at-risk of knee OA, but were without knee symptoms or radiographic knee OA, were investigated. Participants indicated the presence and laterality of foot/ankle symptoms at baseline. The main outcome was development of knee symptoms (pain, aching or stiffness in and around the knee on most days of the month for at least 1 month in the past year). A secondary outcome was development of symptomatic radiographic knee OA (symptoms plus Kellgren and Lawrence [KL] grade ≥2), over the subsequent 4 years. Associations between foot/ankle symptoms and study outcomes were assessed by logistic regression models.\ud \ud Results\ud Foot/ankle symptoms in either or both feet significantly increased the odds of developing knee symptoms (adjusted odds ratio (OR) 1.55, 95% confidence interval (CI) 1.10 to 2.19), and developing symptomatic radiographic knee OA (adjusted OR 3.28, 95% CI 1.69 to 6.37). Based on laterality, contralateral foot/ankle symptoms were associated with developing both knee symptoms (adjusted OR 1.68, 95% CI 1.05 to 2.68) and symptomatic radiographic knee OA (adjusted OR 3.08, 95% CI 1.06 to 8.98), whilst bilateral foot/ankle symptoms were associated with developing symptomatic radiographic knee OA (adjusted OR 4.02, 95% CI 1.76 to 9.17).\ud \ud Conclusion\ud In individuals at-risk of knee OA, the presence of contralateral foot/ankle symptoms in particular increases risk of developing both knee symptoms and symptomatic radiographic knee OA.

Background:The lifetime prevalence of lower back pain is between 60% and 70%, with surgical treatments spared for those not responding to other options.Objectives:To investigate the age, gender and socio-economic status differences in back pain procedures in the UK between 2000, 2008 and 2016.Methods:Data was obtained from primary care electronic medical records (CPRD GOLD) linked to English hospital admissions data. Lower back procedures in patients aged 35+ were identified using OPCS-4 codes for Decompression (Dc), Fusion (F), Therapeutic injections (TI) and Denervation (Dn). Standardised incidence rates (IR) of each type of lower back procedures were calculated per 10,000 CPRD registered person years for each age group, gender, region and SES strata in 2000, 2008 and 2016. IR were also calculated for combinations of age and gender. Negative binomial regression calculated incidence rate ratios (IRR) and 95% confidence intervals.Results:The IR of lower back procedures was 21.5 [20.7, 22.3] per 10,000 person years in 2000. This doubled by 2008 (45.5 [44.5, 46.5]) and trebled by 2016 (62.5 [60.8, 64.2]). Number of events and incidence rates of each procedure type are shown in table 1 below. The incidence of Dn has increased 6-fold whilst Dc and F have doubled. Female (IR in 2016 of 73.99 [71.43, 76.61] vs 50.08 [47.90, 52.33] in men, IRR 1.50 [1.41, 1.59]) and age are associated with back procedure rates (figure 1). Large socio-economic differences were observed, with higher procedure rates seen in the most deprived areas. These differences did however narrow over time during the study period (figure 2).Table 1.Event numbers and incidence rates of different types of lower back procedure.FusionDecompressionTherapeutic InjectionDenervationEventsIR (95% CI)EventsIR (95% CI)EventsIR (95% CI)EventsIR (95% CI)20001090.86 (0.71, 1.04)4663.69 (3.36, 4.04)203516.11 (15.42, 16.82)910.72 (0.58, 0.88)20083331.77 (1.58, 1.97)11976.35 (6.00, 6.72)628333.35 (32.53, 34.18)5963.16 (2.91, 3.43)20161591.93 (1.65, 2.26)5256.39 (5.85, 6.96)386547.03 (45.56, 48.54)4875.93 (5.41, 6.48)Figure 1.Age and Gender stratified incidence rate ratios of all back procedures in 2000, 2008 and 2016Figure 2.Deprivation status incidence rate ratios by yearConclusion:The incidence of lower back procedures has more than trebled since 2000. Women are more likely to have lower back procedures than men, with patients aged 65-74 the most likely to have a procedure. Procedures in those aged 75+ have become more common over time, potentially increasing the risk of post-operative complications. Socio-economic differences in the incidence of low back procedures are probably related to the known higher prevalence of back pain in deprived areas. Whether the observed narrowing in socio-economic variation over time is explained by a reduced need or by lowered provision needs further research.Disclosure of Interests:Danielle E Robinson: None declared, Jennifer Lane: None declared, Richard Craig: None declared, Andrew Judge: None declared, James Bailey: None declared, Dahai Yu: None declared, Kelvin Jordan: None declared, George Peat: None declared, Ross Wilkie: None declared, Alan Silman: None declared, Victoria Y Strauss: None declared, Daniel Prieto-Alhambra Grant/research support from: Professor Prieto-Alhambra has received research Grants from AMGEN, UCB Biopharma and Les Laboratoires Servier, Consultant of: DPA’s department has received fees for consultancy services from UCB Biopharma, Speakers bureau: DPA’s department has received fees for speaker and advisory board membership services from Amgen

In the last Research Made Simple Series article, we briefly outlined the main phenomenological research approaches in relation to investigating healthcare phenomena including Interpretative Phenomenological Analysis (IPA). IPA was originally developed as a method to undertake experiential research in psychology1 and has gained prominence across health and social sciences as a way to understand and interpret topics which are complex and emotionally laden, such as illness experiences.2 In this article, we detail in more depth, the philosophical and methodological nuances of IPA. The aim of IPA is to uncover what a lived experience means to the individual through a process of in depth reflective inquiry.3 IPA draws on phenomenological thinking, with the purpose to return ‘to the things themselves’ (p 168).4 However, IPA also acknowledges that we are each influenced by the worlds in which we live in and the experiences we encounter. Therefore, IPA is an interpretative process between the researcher and researched, influenced predominantly by Heidegger’s interpretive phenomenology, hermeneutics and idiography,2 3 summarised in table 1. View this table: Table 1 Philosophical …

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ObjectivesEffects of the UK Department of Health’s national Enhanced Recovery After Surgery (ERAS) Programme on outcomes after primary hip replacement.DesignNatural experimental study using interrupted time series to assess the changes in trends before, during and after ERAS implementation (April 2009 to March 2011).SettingSurgeries in the UK National Joint Registry were linked with Hospital Episode Statistics containing inpatient episodes from National Health Service trusts in England and patient reported outcome measures.ParticipantsPatients aged ≥18 years from 2008 to 2016.Main outcome measuresRegression coefficients of monthly means of length of hospital stay, bed day cost, change in Oxford Hip Scores (OHS) 6 months post-surgery, complications 6 months post-surgery and revision rates 5 years post-surgery.Results438 921 primary hip replacements were identified. Hospital stays shortened from 5.6 days in April 2008 to 3.6 in December 2016. There were also improvements in bed day costs (£7573 in April 2008 to £5239 in December 2016), positive change in self-reported OHS from baseline to 6 months post-surgery (17.7 points in April 2008 to 22.9 points in December 2016), complication rates (4.1% in April 2008 to 1.7% March 2016) and 5 year revision rates (5.9 per 1000 implant-years (95% CI 4.8 to 7.2) in April 2008 to 2.9 (95% CI 2.2 to 3.9) in December 2011). The positive trends in all outcomes started before ERAS was implemented and continued during and after the programme.ConclusionsPatient outcomes after hip replacement have improved over the last decade. A national ERAS programme maintained this improvement but did not alter the existing rate of change.

ObjectivesTo identify potentially modifiable factors that mediate the association between symptomatic osteoarthritis (OA) and premature mortality.MethodsA population-based prospective cohort study; primary care medical record data were linked to self-report information collected by questionnaire in adults aged 50 years and over (n=10 415). OA was defined by primary care consultation and moderate-to-severe pain interference in daily life. A Cox proportional hazards analysis determined the total effect (TE) of OA on mortality after adjustment for potential confounders. Within the Cox model, path analysis was used to decompose the TE to assess the indirect and direct effects for selected potential mediators (anxiety, depression, unrefreshed sleep and walking frequency). Results are expressed as HRs with 95% CIs derived from bootstrap resampling.ResultsOA was significantly associated with mortality (TE-adjusted HR 1.14; 95% CI 1.00 to 1.29). The indirect effects for walking frequency were 1.05 (95% CI 1.04 to 1.06), depression 1.02 (95% CI 1.02 to 1.03), anxiety 1.01 (95% CI 1.00 to 1.02) and unrefreshed sleep 1.01 (95% CI 1.00 to 1.01).ConclusionsThe analysis indicates that encouraging people to walk and ‘get out and about’ in addition to targeting OA could be protective against excessive mortality. The findings also suggest that depression, anxiety and unrefreshed sleep have a role in premature mortality for people with OA; however, this has low clinical significance.

Key Points Question Are hospital organizational factors, surgical factors, and patient factors associated with patient outcomes and National Health Service costs for total hip and knee replacement? Findings This cohort study of more than 383 000 patients in 207 health areas in England identified significant health area–level variation in patient outcomes for total hip and knee replacement surgery. Geographical variation was associated with better outcomes for surgical procedures in private and high-volume hospitals as well as for operations performed by more experienced surgeons with a higher volume of operations per year. Meaning Findings are informative for commissioners in monitoring variations in surgical outcomes and for patients deciding where to undergo surgery., This cohort study evaluates variation in patient outcomes and costs for primary hip and knee replacement across health areas in England and identifies whether patient, surgical, or hospital factors are associated with such variation., Importance Little is known about variation in outcomes of surgery or about the factors associated with such variation. Objectives To evaluate variation in patient outcomes and costs for primary hip and knee replacement across health areas in England and to identify whether patient, surgical, or hospital factors are associated with such variation. Design, Setting, and Participants This cohort study used data from the National Joint Registry, linked to English Hospital Episode Statistics and Patient Reported Outcome Measures data sets, for 383 382 adult patients who underwent primary total hip replacement (THR) or primary total and unicompartmental knee replacement (TKR) surgical procedures from January 2014 to December 2016. Geographical Information Systems were used to display maps describing adjusted estimates of variation in outcomes across health areas. Data analysis took place from January 2018 to August 2019. Exposures Patient characteristics (eg, age, sex, body mass index [BMI], and socioeconomic deprivation), surgical factors (eg, surgeon volume and grade), and hospital organizational factors (eg, number of operating theaters, number of specialist consultants, and hospital volume). Main Outcomes and Measures Length of stay (LOS), bed-day costs, change in Oxford hip or knee scores 6 months after surgery, and complications 6 months after surgery. Results A total of 173 107 patients (mean [SD] age, 69.3 [10.7] years; mean [SD] BMI, 28.9 [5.2]) underwent primary THR and 210 275 patients (mean [SD] age 69.7 [9.4] years; mean [SD] BMI, 31.1 [5.5]) underwent primary TKR, nested in 207 health areas. A number of factors were associated with longer LOS, higher bed-day costs, smaller changes in Oxford hip or knee scores, and a higher percentage of complications, including a workforce with a higher number of less experienced physicians (eg, LOS for less experienced surgeons, THR: regression coefficient, 0.02; 95% CI, 0.01 to 0.03; P 150 surgical procedures per year, THR: regression coefficient, −1.03; 95% CI, −1.47 to −0.58; P

Summary Objective To investigate trends in gabapentinoid prescribing in patients with osteoarthritis (OA). Methods Patients aged 40 years and over with a new OA diagnosis recorded between 1995 and 2015 were identified in the Clinical Practice Research Datalink (CPRD) and followed to first prescription of gabapentin or pregabalin, or other censoring event. We estimated the crude and age-standardised annual incidence rates of gabapentinoid prescribing, stratified by patient age, sex, geographical region, and time since OA diagnosis, and the proportion of prescriptions attributable to OA, or to other conditions representing licensed and unlicensed indications for a gabapentinoid prescription. Results Of 383,680 newly diagnosed OA cases, 35,031 were prescribed at least one gabapentinoid. Irrespective of indication, the annual age-standardised incidence rate of first gabapentinoid prescriptions rose from 1.6 [95% confidence interval (CI): 1.3, 2.0] per 1000 person-years in 2000, to 27.6 (26.7, 28.4) in 2015, a trend seen across all ages and not explained by length of follow-up. Rates were higher among women, younger patients, and in Northern Ireland, Scotland and the North of England. Approximately 9% of first prescriptions could be attributed to OA, a further 13% to comorbid licensed or unlicensed indications. Conclusion Gabapentinoid prescribing in patients with OA increased dramatically between 1995 and 2015. In most cases, diagnostic codes for licensed or unlicensed indications were absent. Gabapentinoid prescribing may be attributable to OA in a significant proportion but evidence for their effectiveness in OA is lacking. Further research to investigate clinical decision making around prescribing these expensive and potentially harmful medicines is recommended.

Background There is limited evidence concerning the effectiveness of enhanced recovery programmes in hip and knee replacement surgery, particularly when applied nationwide across a health-care system. Objectives To determine the effect of hospital organisation, surgical factors and the enhanced recovery after surgery pathway on patient outcomes and NHS costs of hip and knee replacement. Design (1) Statistical analysis of national linked data to explore geographical variations in patient outcomes of surgery. (2) A natural experimental study to determine clinical effectiveness of enhanced recovery after surgery. (3) A qualitative study to identify barriers to, and facilitators of, change. (4) Health economics analysis to establish NHS costs and cost-effectiveness. Setting Data from the National Joint Registry, linked to English Hospital Episode Statistics and patient-reported outcome measures in both the geographical variation and natural experiment studies, together with the economic evaluation. The ethnographic study took place in four hospitals in a region of England. Participants Qualitative study – 38 health professionals working in hip and knee replacement services in secondary care and 37 patients receiving hip or knee replacement. Interventions Natural experiment – implementation of enhanced recovery after surgery at each hospital between 2009 and 2011. Enhanced recovery after surgery is a complex intervention focusing on several areas of patients’ care pathways through surgery: preoperatively (patient is in best possible condition for surgery), perioperatively (patient has best possible management during and after operation) and postoperatively (patient experiences best rehabilitation). Main outcome measures Patient-reported pain and function (Oxford Hip Score/Oxford Knee Score); 6-month complications; length of stay; bed-day costs; and revision surgery within 5 years. Results Geographical study – there are potentially unwarranted variations in patient outcomes of hip and knee replacement surgery. This variation cannot be explained by differences in patients, case mix, surgical or hospital organisational factors. Qualitative – successful implementation depends on empowering patients to work towards their recovery, providing post-discharge support and promoting successful multidisciplinary team working. Care processes were negotiated between patients and health-care professionals. ‘Good care’ remains an aspiration, particularly in the post-discharge period. Natural experiment – length of stay has declined substantially, pain and function have improved, revision rates are in decline and complication rates remain stable. The introduction of a national enhanced recovery after surgery programme maintained improvement, but did not alter the rate of change already under way. Health economics – costs are high in the year of joint replacement and remain higher in the subsequent year after surgery. There is a strong economic incentive to identify ways of reducing revisions and complications following joint replacement. Published cost-effectiveness evidence supports enhanced recovery pathways as a whole. Limitations Short duration of follow-up data prior to enhanced recovery after surgery implementation and missing data, particularly for hospital organisation factors. Conclusion No evidence was found to show that enhanced recovery after surgery had a substantial impact on longer-term downwards trends in costs and length of stay. Trends of improving outcomes were seen across all age groups, in those with and without comorbidity, and had begun prior to the formal enhanced recovery after surgery roll-out. Reductions in length of stay have been achieved without adversely affecting patient outcomes, yet, substantial variation remains in outcomes between hospital trusts. Future work There is still work to be done to reduce and understand unwarranted variations in outcome between individual hospitals. Study registration This study is registered as PROSPERO CRD42017059473. Funding This project was funded by the National Institute for Health Research (NIHR) Health Services and Delivery Research programme and will be published in full in Health Services and Delivery Research; Vol. 8, No. 4. See the NIHR Journals Library website for further project information.

The classification and monitoring of individuals with early knee osteoarthritis (OA) are important considerations for the design and evaluation of therapeutic interventions and require the identification of appropriate outcome measures. Potential outcome domains to assess for early OA include patient-reported outcomes (such as pain, function and quality of life), features of clinical examination (such as joint line tenderness and crepitus), objective measures of physical function, levels of physical activity, features of imaging modalities (such as of magnetic resonance imaging) and biochemical markers in body fluid. Patient characteristics such as adiposity and biomechanics of the knee could also have relevance to the assessment of early OA. Importantly, research is needed to enable the selection of outcome measures that are feasible, reliable and validated in individuals at risk of knee OA or with early knee OA. In this Perspectives article, potential outcome measures for early symptomatic knee OA are discussed, including those measures that could be of use in clinical practice and/or the research setting.

Background In the UK, the Health and Social Care Act 2012, places duties on the NHS Commissioning Board and Clinical Commissioning Groups (CCG) to have regard to the need to reduce variations in access to, and outcomes from, health care services for patients1. There are well known geographical variations in the uptake of common surgical procedures including knee replacement2. Much less is known about variations in outcomes of surgery and factors that can explain why such variation exists. Objectives Our aim was to explore variation in patients’ outcomes for primary total or unicomparmental knee replacement (TKR/UKR) surgery across CCGs, and to identify whether patient, surgical and hospital factors can explain why such variation exists. Methods We used the National Joint Registry, which incorporates data on knee replacement surgeries. Primary operations were linked with Hospital Episode Statistics data which contains records of all inpatient episodes undertaken in NHS hospitals, and Patient Reported Outcome Measures (PROMs). Primary TKR/UKR in people aged 18 years or over between 2014 and 2016 were identified. Multilevel regression models were generated for the following outcomes: length of stay (LOS), bed costs, change in Oxford knee score (OKS) 6-months after surgery, and complication by 6 months. Models included a wide range of patient, surgical and hospital organisation factors. Geographical Information Systems are used to display maps describing adjusted estimates of variation in outcomes across NHS CCG areas. Results 210,725 primary TKR/UKR were identified nested in 207 clinical commissioning group areas. 57% of patients were women, with an average age 70 years (SD ±9 years). Whilst we identified a number of factors that predicted outcomes of surgery (e.g. age, gender, co-morbidity, deprivation, baseline function, surgical volume, numbers of orthopaedic surgeons, beds, operating theatres), these factors did not explain the observed geographical variations in outcomes of surgery across CCGs. The absolute predicted change in OKS varied from 13.0 to 18.8, predicted 6-month complication rate from 2.9% to 5.8%, predicted revision from primary TKR/UKR undertaken in 2014-2016 0.7% to 1.8%, predicted mean length of stay 2.9 to 6.6 days, bed-day cost £4758 to £8693 (Figure). Conclusion We have identified potentially unwarranted variations in patient outcomes of knee replacement surgery. This variation cannot be explained by differences in patients case mix, surgical factors, or hospital organisational factors. This information is informative to patients in making a decision in where they have their surgery, and to commissioners in monitoring variations in outcomes of surgery. References [1] Geographic Variations in Health Care. What Do We Know and What Can Be Done to Improve Health System Performance?2014:23. [2] Judge A, Welton NJ, Sandhu J, et al. Equity in access to total joint replacement of the hip and knee in England: cross sectional study. BMJ 2010;341 doi: 10.1136/bmj.c4092 Acknowledgement We would like to thank the patients and staff of all the hospitals in England and Wales who have contributed data to the National Joint Registry (NJR). The authors thank Ed Burn for his advice using R. Disclosure of Interests Cesar Garriga: None declared, Jose Leal: None declared, Andrew Price Consultant for: Zimmer Biomet, Daniel Prieto-Alhambra Grant/research support from: Grants from Amgen, UCB Biopharma and Servier outside the submitted work, Consultant for: UCB Biopharma, Speakers bureau: Amgen, Andrew Carr: None declared, Amar Rangan Grant/research support from: Grants from ORUK and from DePuy Ltd, outside the submitted work., Cyrus Cooper Consultant for: Personal fees from Alliance for Better Bone Health, Amgen, Eli Lilly, GSK, Medtronic, Merck, Novartis, Pfizer, Roche, Servier, Takeda and UCB., Raymond Fitzpatrick: None declared, Karen Barker: None declared, George Peat: None declared, Nigel Arden Grant/research support from: Grants from BIOIBERICA, and from MERCK., Consultant for: Personal fees from Flexion, from Regeneron, from Freshfields Bruckhaus Deringer, outside the submitted work., Andrew Judge Grant/research support from: Consortium research grants from Roche, Consultant for: Received consultancy fees, lecture fees and honoraria from Servier, UK Renal Registry, Oxford Craniofacial Unit, IDIAP Jordi Gol and Freshfields Bruckhaus. Member of Deringer Data Safety and Monitoring Board for Anthera Pharmaceuticals, Inc. Consultancy for Freshfields Bruckhaus Deringer