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Objectives To evaluate the longitudinal impact of introducing a national, direct access physiotherapy model of care on the rates of primary and secondary care consultations for musculoskeletal (MSK) conditions.Design Interrupted time series analysis using segmented linear regression.Setting Norway primary careParticipants A cohort of 82 072 participants was derived from 3 population-based health surveys conducted across separate geographical regions in Norway. All participants surveyed were eligible for inclusion as a national representative sample of the Norwegian population. Registered MSK consultations were linked to the Norwegian Control and Payment of Health Reimbursement database and the Norwegian Patient Register using the International Classification of Primary Care diagnostic medical codes L-chapter for MSK conditions and spine related International Classification of Diseases, 10th Revision, codes.Intervention Direct access to physiotherapy model of care introduced nationally in Norway in 2018. This model allowed Norwegians to consult directly with qualified physiotherapists for MSK conditions (eg, back pain, knee osteoarthritis) without the need for a medical referral in order to claim a social security reimbursement.Main outcomes measured Rates of primary care consultations per 10 000 population (general practitioner (GP) and physiotherapist consultations) and secondary care (specialist consultations and surgical procedures) measured from 2014 to 2021.Results The introduction of the direct access physiotherapy model was associated with an immediate stepped reduction of 391 general practice consultations per 10 000 population, (95% CI: −564 to −216), without an associated change in physiotherapy consultations. Subgroup analyses suggested there was an associated reduction in physiotherapy consultations for those in the lowest education group of 150 consultations per quarter (95% CI:−203 to −97), 70 consultations per quarter in the intermediate education group (95% CI:−115 to −27) and a stepped reduction of 2 spinal surgical procedures per 10 000 population, for those aged between 40 and 60 years (95% CI: −3 to −1) following the introduction of the direct access physiotherapy model.Conclusion The national introduction of a direct access to physiotherapy model of care was associated with a reduction in the workload of GPs for the management of MSK conditions. The use of physiotherapists in direct contact roles is a potential strategic model to reduce the burden on the GP workforce in primary care worldwide.

Abstract Background Back pain is the number one condition contributing to years lived with disability worldwide, and one of the most common reasons for seeking primary care. Research on this condition in the ageing population is sparse. Further, the heterogeneity of patients with back pain complicates the management in clinical care. It is possible that subgrouping people with similar characteristics would improve management. This paper aimed to identify latent classes based on demographics, pain characteristics, psychosocial behavior, and beliefs and attitudes about back pain, among older patients seeking primary care with a new episode of back pain, and to examine if there were differences regarding the classes’ first point-of-contact. Methods The study was part of the international BACE (Back complaints in elders) consortium and included 435 patients aged ≥ 55 years seeking primary care (general practitioners, physiotherapists, and chiropractors) in Norway from April 2015 to March 2020. A latent class analysis was performed to identify latent classes. The classes were described in terms of baseline characteristics and first point-of-contact in primary care. Results Four latent classes were identified. The mean age was similar across groups, as were high expectations towards improvement. Class 1 (n = 169, 39%), the “positive” class, had more positive attitudes and beliefs, less pain catastrophizing and shorter duration of current pain episode. Class 2 (n = 31, 7%), the “fearful” class, exhibited the most fear avoidance behavior, and had higher mean pain intensity. Class 3 (n = 33, 8%), the “distressed” class, had the highest scores on depression, disability, and catastrophizing. Finally, class 4 (n = 202, 46%), the “hopeful” class, showed the highest expectations for recovery, although having high pain intensity. The identified four classes showed high internal homogeneity, sufficient between-group heterogeneity and were considered clinically meaningful. The distribution of first point-of-contact was similar across classes, except for the positive class where significantly more patients visited chiropractors compared to general practitioners and physiotherapists. Conclusions The identified classes may contribute to targeting clinical management of these patients. Longitudinal research on these latent classes is needed to explore whether the latent classes have prognostic value. Validation studies are needed to evaluate external validity. Trial registration Clinicaltrials.gov NCT04261309.

Introduction Bacterial infection and Modic changes (MCs) as causes of low back pain (LBP) are debated. Results diverged between two randomised controlled trials examining the effect of amoxicillin with and without clavulanic acid versus placebo on patients with chronic LBP (cLBP) and MCs. Previous biopsy studies have been criticised with regard to methods, few patients and controls, and insufficient measures to minimise perioperative contamination. In this study, we minimise contamination risk, include a control group and optimise statistical power. The main aim is to compare bacterial growth between patients with and without MCs.Methods and analysis This multicentre, case–control study examines disc and vertebral body biopsies of patients with cLBP. Cases have MCs at the level of tissue sampling, controls do not. Previously operated patients are included as a subgroup. Tissue is sampled before antibiotic prophylaxis with separate instruments. We will apply microbiological methods and histology on biopsies, and predefine criteria for significant bacterial growth, possible contamination and no growth. Microbiologists, surgeons and pathologist are blinded to allocation of case or control. Primary analysis assesses significant growth in MC1 versus controls and MC2 versus controls separately. Bacterial disc growth in previously operated patients, patients with large MCs and growth from the vertebral body in the fusion group are all considered exploratory analyses.Ethics and dissemination The Regional Committees for Medical and Health Research Ethics in Norway (REC South East, reference number 2015/697) has approved the study. Study participation requires written informed consent. The study is registered at ClinicalTrials.gov (NCT03406624). Results will be disseminated in peer-reviewed journals, scientific conferences and patient fora.Trial registration number NCT03406624.

Objective: Developmental dysplasia of the hip (DDH) is a congenital condition affecting 2–3% of all infants. DDH increases the risk of osteoarthritis, is the cause of 30 ​% of all total hip arthroplasties (THAs) in adults

ABSTRACTThe collateral impact of antibiotics on the microbiome has attained increasing attention. However, the ecological consequences of long-term antibiotic exposure on the gut microbiome, including antibiotic resistance, are still limited. Here, we investigated long-term exposure effects to amoxicillin on the human gut microbiome and resistome. Fecal samples were collected from 20 patients receiving 3-months of amoxicillin or placebo treatment as part of a Norwegian multicenter clinical trial on chronic low back pain (AIM study). Samples were collected at baseline, last day of treatment, and 9 months after antibiotic cessation. The abundance and diversity of microbial and resistome composition were characterized using whole shotgun and functional metagenomic sequencing data. While the microbiome profiles of placebo subjects were stable over time, discernible changes in diversity and overall microbiome composition were observed after amoxicillin treatment. In particular, health-associated short-chain fatty acid producing species significantly decreased in proportion. However, these changes were short-lived as the microbiome showed overall recovery 9 months post-treatment. On the other hand, exposure to long-term amoxicillin was associated with an increase in total antimicrobial resistance gene load and diversity of antimicrobial resistance genes, with persistent changes even at 9 months post-treatment. Additionally, beta-lactam resistance was the most affected antibiotic class, suggesting a targeted response to amoxicillin, although changes at the gene level varied across individuals. Overall, our results suggest that the impact of prolonged amoxicillin exposure was more explicit and long-lasting in the fecal resistome than in microbiome composition. Such information is relevant for designing rational administration guidelines for antibiotic therapies.

Abstract Background There are indications that use of menopausal hormone therapy (MHT) and oral contraceptives (OC) increases the risk of low back pain (LBP), with higher oestrogen levels involved in the underlying mechanisms. The purpose of the present study was to investigate associations between use of systemic MHT or OC and risk of chronic LBP in a large population-based data set. Methods Data were obtained from two surveys in the Trøndelag Health Study in Norway, HUNT2 (1995–1997) and HUNT3 (2006–2008). A cross-sectional study of association between use of systemic MHT and prevalence of chronic LBP comprised 12,974 women aged 40–69 years in HUNT2, with 4007 women reporting chronic LBP. A cohort study involving MHT comprised 6007 women without chronic LBP at baseline in HUNT2, and after 11 years 1245 women reported chronic LBP at follow-up in HUNT3. The cross-sectional study of association with use of OC included 23,593 women aged 20–69 years in HUNT2, with 6085 women reporting chronic LBP. The corresponding cohort study included 10,586 women without chronic LBP at baseline in HUNT2, of whom 2084 women reported chronic LBP in HUNT3. Risk of chronic LBP was examined in both study designs in generalised linear models with adjustment for potential confounders. Results In the cohort study, current users of systemic MHT at baseline showed a greater risk of chronic LBP (relative risk (RR) 1.30; 95% CI: 1.14–1.49; compared with never users). The risk increased according to duration of MHT use (P for linear trend = 0.003). Known users of systemic MHT based exclusively on oestrogen experienced the highest risk (RR 1.49; 95% CI: 1.16–1.91), but an increased risk was also seen among known users of oestrogen-progestin combination MHT (RR 1.35; 95% CI: 1.16–1.57). A slight increase in risk of chronic LBP was found in the cohort study among former users of OC (RR 1.17; 95% CI: 1.06–1.30; compared with never users). Conclusions Long-lasting use of systemic MHT, in particular therapy based on oestrogen only, is associated with greater risk of chronic LBP. Having been a user of OC most likely entails a minor increase in risk.

Abstract Background Fatty infiltration of the paraspinal muscles may play a role in pain and disability in lumbar spinal stenosis. We assessed the reliability and association with clinical symptoms of a method for assessing fatty infiltration, a simplified muscle fat index (MFI). Methods Preoperative axial T2-weighted magnetic resonance imaging (MRI) scans of 243 patients aged 66.6 ± 8.5 years (mean ± standard deviation), 119 females (49%), with symptomatic lumbar spinal stenosis were assessed. Fatty infiltration was assessed using both the MFI and the Goutallier classification system (GCS). The MFI was calculated as the signal intensity of the psoas muscle divided by that of the multifidus and erector spinae. Observer reliability was assessed in 102 consecutive patients for three independent investigators by intraclass correlation coefficient (ICC) and 95% limits of agreement (LoA) for continuous variables and Gwet’s agreement coefficient (AC1) for categorical variables. Associations with patient-reported pain and disability were assessed using univariate and multivariate regression analyses. Results Interobserver reliability was good for the MFI (ICC 0.79) and fair for the GCS (AC1 0.33). Intraobserver reliability was good or excellent for the MFI (ICC range 0.86–0.91) and moderate to almost perfect for the GCS (AC1 range 0.55–0.92). Mean interobserver differences of MFI measurements ranged from -0.09 to -0.04 (LoA -0.32 to 0.18). Adjusted for potential confounders, none of the disability or pain parameters was significantly associated with MFI or GCS. Conclusion The proposed MFI demonstrated high observer reliability but was not associated with preoperative pain or disability.

Abstract Background Modic Changes (MCs) in the vertebral bone marrow were related to back pain in some studies but have uncertain clinical relevance. Diffusion weighted MRI with apparent diffusion coefficient (ADC)-measurements can add information on bone marrow lesions. However, few have studied ADC measurements in MCs. Further studies require reproducible and valid measurements. We expect valid ADC values to be higher in MC type 1 (oedema type) vs type 3 (sclerotic type) vs type 2 (fatty type). Accordingly, the purpose of this study was to evaluate ADC values in MCs for interobserver reproducibility and relation to MC type. Methods We used ADC maps (b 50, 400, 800 s/mm2) from 1.5 T lumbar spine MRI of 90 chronic low back pain patients with MCs in the AIM (Antibiotics In Modic changes)-study. Two radiologists independently measured ADC in fixed-sized regions of interests. Variables were MC-ADC (ADC in MC), MC-ADC% (0% = vertebral body, 100% = cerebrospinal fluid) and MC-ADC-ratio (MC-ADC divided by vertebral body ADC). We calculated mean difference between observers ± limits of agreement (LoA) at separate endplates. The relation between ADC variables and MC type was assessed using linear mixed-effects models and by calculating the area under the receiver operating characteristic curve (AUC). Results The 90 patients (mean age 44 years; 54 women) had 224 MCs Th12-S1 comprising type 1 (n = 111), type 2 (n = 91) and type 3 MC groups (n = 22). All ADC variables had higher predicted mean for type 1 vs 3 vs 2 (p 50% of their mean value was less frequent for MC-ADC (9% of MCs) vs MC-ADC% and MC-ADC-ratio (17–20%). Conclusions The MC-ADC variable (highest mean ADC in the MC) had best interobserver reproducibility, discriminated between MC type groups, and may be used in further research. ADC values differed between MC types as expected from previously reported MC histology.

Objectives The purpose of this study was to investigate whether self-reported musculoskeletal pain (MSP) was associated with a future anterior cruciate ligament reconstruction (ACLR).Methods In this population-based prospective cohort study, we included 8087 participants from the adolescent part of the Trøndelag Health Study (Young-HUNT) in Norway. The exposure was self-reported MSP from the Young-HUNT3 study (2006–2008), which was categorised into two MSP load groups (high MSP and low MSP) based on frequency and number of pain sites. The outcome was ACLRs recorded in the Norwegian Knee Ligament Register between 2006 and 2019. Logistic regression was used to investigate association between MSP load and ACLR, given as ORs with 95% CIs. All tests were two-sided and p values of ≤0.05 were considered statistically significant.Results 8087 adolescents were included. We identified a total of 99 ACLRs, with 6 ACLRs (0.9%) in adolescents who reported high MSP load and 93 ACLRs (1.3%) among those who reported low MSP load. Adolescents reporting high MSP load had 23% lower odds of an ACLR (OR 0.77, 95% CI 0.31 to 1.91) compared with adolescents with low MSP load. However, the CIs were very wide.Conclusion Self-reported high MSP load in adolescents was not associated with increased risk of future ACLR. Although the number of participants was high, the relatively few cases of ACLR mean that we cannot be conclusive about the presence or absence of an association.

Abstract Background Back pain is an extensive burden to our healthcare system, yet few studies have explored modifiable prognostic factors associated with high costs related to healthcare utilization, especially among older back pain patients. The aims of this study were to identify modifiable prognostic factors for high costs related to healthcare utilization among older people seeking primary care with a new episode of back pain; and to replicate the identified associations in a similar cohort, in a different country. Methods Data from two cohort studies within the BACE consortium were used, including 452 and 675 people aged ≥55 years seeking primary care with a new episode of back pain. High costs were defined as costs in the top 25th percentile. Healthcare utilization was self-reported, aggregated for one-year of follow-up and included: primary care consultations, medications, examinations, hospitalization, rehabilitation stay and operations. Costs were estimated based on unit costs collected from national pricelists. Nine potential modifiable prognostic factors were selected based on previous literature. Univariable and multivariable binary logistic regression models were used to identify and replicate associations (crude and adjusted for selected covariates) between each modifiable prognostic factor and high costs related to healthcare utilization. Results Four modifiable prognostic factors associated with high costs related to healthcare utilization were identified and replicated: a higher degree of pain severity, disability, depression, and a lower degree of physical health-related quality of life. Kinesiophobia and recovery expectations showed no prognostic value. There were inconsistent results across the two cohorts with regards to comorbidity, radiating pain below the knee and mental health-related quality of life. Conclusion The factors identified in this study may be future targets for intervention with the potential to reduce high costs related to healthcare utilization among older back pain patients. Trial registration ClinicalTrials.gov NCT04261309, 07 February 2020. Retrospectively registered.

Abstract Background Demands of physical work are related to musculoskeletal disorders, and hence, important to assess. The Physical Workload Questionnaire (PWQ) is based on 26 items related to physical workload. The PWQ has been translated into Norwegian, but its psychometric properties have not yet been tested. The aim of this study was to assess the validity and reliability of the PWQ among patients with musculoskeletal disorders. Methods A cross-sectional study with a test-retest design was conducted to assess construct validity (structural validity and hypothesis testing) and reliability (internal consistency and test-retest reliability) among employed patients with musculoskeletal disorders. Exploratory factor analysis was performed to assess the structural validity and number of items to be included in the Norwegian version of the PWQ. Hypothesis testing was assessed by 14 a priori hypotheses (“known” group, convergent and discriminant validity). Internal consistency was evaluated using Cronbach’s alpha and test-retest reliability by Intraclass Correlation Coefficient (ICC2.1), Standard Error of Measurement (SEMagreement) and Smallest Detectable Change (SDC95%ind). Results In total, 115 patients with a mean age (SD) of 46 (9) years were included, of which 48 were included in the reliability analyses. Exploratory factor analysis resulted in two subscales: “Heavy physical work” (15 items, range 0–100) and “Long-lasting postures and repetitive movements” (7 items, range 0–100). No floor or ceiling effects were seen in the subscales. Twelve of the 14 (85%) predefined hypotheses were confirmed. The internal consistency with Cronbach’s alpha was 0.94 and 0.85 on subscales 1 and 2, respectively. Test-retest reliability analyses demonstrated an ICC2.1 of 0.96 (95% CI 0.88, 0.98) and 0.92 (95% CI 0.81, 0.96), SEM of 6.9 and 10.0 and SDC95%ind of 19.2 and 27.7 of subscales 1 and 2, respectively. Conclusions The Norwegian version of the PWQ demonstrated good validity and reliability and can be used to evaluate physical workload in patients with musculoskeletal disorders.

Abstract Disability and distress caused by chronic low back pain (LBP) lacking clear pathoanatomical explanations cause huge problems both for patients and society. A subgroup of patients has Modic changes (MC), identifiable by MRI as vertebral bone marrow lesions. The cause of such changes and their relationship to pain are not yet understood. We explored the pathobiology of these lesions using profiling of gene expression in blood, coupled with an edema-sensitive MRI technique known as short tau inversion recovery (STIR) imaging. STIR images and total RNA from blood were collected from 96 patients with chronic LBP and MC type I, the most inflammatory MC state. We found the expression of 37 genes significantly associated with STIR signal volume, ten genes with edema abundancy (a constructed combination of STIR signal volume, height, and intensity), and one gene with expression levels significantly associated with maximum STIR signal intensity. Gene sets related to interferon signaling, mitochondrial metabolism and defense response to virus were identified as significantly enriched among the upregulated genes in all three analyses. Our results point to inflammation and immunological defense as important players in MC biology in patients with chronic LBP.

Abstract Background Musculoskeletal pain has a high prevalence in adolescence and causes huge consequences for the individuals and the society. Little knowledge exists on social risk factors for musculoskeletal pain in adolescents. This study aimed to investigate if low social acceptance among peers during the first year of upper secondary school was associated with persistent and severe persistent musculoskeletal pain 2 years later and if psychological distress modified this association. Methods Longitudinal data from the Norwegian Fit Futures Study was used. Students in the first year of upper secondary school answered an electronic questionnaire, covering health status, pain, social acceptance among peers, and psychological distress. Persistent musculoskeletal pain was measured 2 years later. Multiple logistic regression analyses and moderation analyses were conducted adjusting for sex and chronic diseases. Main analyses were conducted on participants without persistent musculoskeletal pain at baseline, and secondary analyses were conducted on all participants with and without persistent musculoskeletal pain at baseline. Results Of 775 participants (52% females), 556 (71.7%) were pain-free at baseline and included in the main analyses. Significant associations between low social acceptance among peers and persistent musculoskeletal pain 2 years later were found in crude (Odds ratio (OR) = 1.8, 95%CI [1.0–3.1]) and adjusted analyses (OR = 1.8, 95%CI [1.0–3.2]). No statistically significant effect modification of psychological distress (p = 0.89) on this association was found. A significant association between low social acceptance and persistent musculoskeletal pain was found in adjusted secondary analyses of all the students (n = 692) (OR = 1.6, 95%CI [1.0–2.3]). Conclusions Our results indicate that low social acceptance among peers increases the risk of future persistent musculoskeletal pain in adolescents. Thus, interventions strengthening adolescent’s social arenas may be helpful to prevent persistent musculoskeletal pain. Trial registration Retrospective registered at clinicaltrials.org NCT04526522 .

Objective Frequent and increasing use of over-the-counter analgesics (OTCA) among adolescents is a public health concern. Prior research indicates that adolescents exposed to traumatic events may be at increased risk of suffering from headaches and musculoskeletal pain. In this study, we assessed the association between trauma exposure and use of OTCA for headaches and musculoskeletal pain.Design A cross-sectional population study among adolescents, self-reported data on trauma exposure, pain and use of OTCA.Setting and participants All 10 608 adolescents aged 13–19 years in a region of Norway were invited in this school-based survey, participation rate was 76%.Outcome measure Frequency of OTCA use for headache and musculoskeletal pain served as separate outcomes in ordinal logistic regression analyses.Results Trauma exposure was significantly and consistently related to higher frequency use of OTCA for headache and musculoskeletal pain, of which associations for bullying (OR 1.79, 95% CI 1.50 to 2.12, and OR 2.12, 95% CI 1.70 to 2.66), physical violence (OR 1.49, 95% CI 1.25 to 1.78 and OR 1.83, 95% CI 1.45 to 2.32) and sexual abuse (OR 1.83, 95% CI 1.55 to 2.18 and OR 1.53, 95% CI 1.18 to 1.90) were particularly strong. A dose–response relationship was found between interpersonal violence and OTCA use for headache (OR 1.46, 95% CI 1.29 to 1.66 for one type and OR 1.81, 95% CI 1.53 to 2.14 for two or more types) and musculoskeletal pain (OR 1.61, 95% CI 1.91 to 3.00 for one type and OR 2.39, 95% CI 1.91 to 3.00 for two or more types). The associations remained significant after adjustment for pain, although an attenuation in strength was observed.Conclusion Trauma exposed adolescents use OTCA for headaches and musculoskeletal pain more frequently than those not exposed. The higher frequency of pain conditions among trauma exposed only partially explained their more frequent OTCA use, indicating an increased risk relating to features beyond frequency of pain.

Long-term antibiotics are prescribed for a variety of medical conditions, recently including low back pain with Modic changes. The molecular impact of such treatment is unknown. We conducted longitudinal transcriptome and epigenome analyses in patients (n = 100) receiving amoxicillin treatment or placebo for 100 days in the Antibiotics in Modic Changes (AIM) study. Gene expression and DNA methylation were investigated at a genome-wide level at screening, after 100 days of treatment, and at one-year follow-up. We identified intra-individual longitudinal changes in gene expression and DNA methylation in patients receiving amoxicillin, while few changes were observed in patients receiving placebo. After 100 days of amoxicillin treatment, 28 genes were significantly differentially expressed, including the downregulation of 19 immunoglobulin genes. At one-year follow-up, the expression levels were still not completely restored. The significant changes in DNA methylation (n = 4548 CpGs) were mainly increased methylation levels between 100 days and one-year follow-up. Hence, the effects on gene expression occurred predominantly during treatment, while the effects on DNA methylation occurred after treatment. In conclusion, unrecognized side effects of long-term amoxicillin treatment were revealed, as alterations were observed in both gene expression and DNA methylation that lasted long after the end of treatment.

Abstract Background Low back pain is common and a significant number of patients experience chronic low back pain. Current treatment options offer small to moderate effects. Patients with vertebral bone marrow lesions visualized as Modic changes on magnetic resonance imaging may represent a subgroup within the low back pain population. There is evidence for inflammatory mediators being involved in development of Modic changes; hence, suppression of inflammation could be a treatment strategy for these patients. This study examines the effect of anti-inflammatory treatment with the TNF-α inhibitor infliximab in patients with chronic low back pain and Modic changes. Methods/design The BackToBasic trial is a multicenter, double blind, randomized controlled trial conducted at six hospitals in Norway, comparing intravenous infusions with infliximab with placebo. One hundred twenty-six patients aged 18–65 with chronic low back pain and type 1 Modic changes will be recruited from secondary care outpatients’ clinics. The primary outcome is back pain-specific disability at day 154 (5 months). The study is designed to detect a difference in change of 10 (SD 18) in the Oswestry Disability Index at day 154/ 5 months. The study also aims to refine MRI-assessment, investigate safety and cost-effectiveness and explore the underlying biological mechanisms of Modic changes. Discussion Finding treatments that target underlying mechanisms could pose new treatment options for patients with low back pain. Suppression of inflammation could be a treatment strategy for patients with low back pain and Modic changes. This paper presents the design of the BackToBasic study, where we will assess the effect of an anti-inflammatory treatment versus placebo in patients with chronic low back pain and type 1 Modic changes. The study is registered at ClinicalTrials.gov under the identifier NCT03704363 . The EudraCT Number: 2017–004861-29.

Abstract Background Associations between childbirths and subsequent risk of low back pain (LBP) have not been clarified. Changes in sex hormone levels or lumbar posture during pregnancy may have an impact on LBP later in life. The purpose of this study was to explore associations between the number of childbirths, age at childbirths and prevalence of chronic LBP in a general population of women. Methods Data were obtained from the Norwegian community-based Nord-Trøndelag Health Study, HUNT2 (1995–1997). Women aged 20–69 years indicated whether they suffered from chronic LBP, defined as LBP persisting at least 3 months continuously during last year. Information about LBP was collected from 3936 women who had experienced no childbirths, 3143 women who had delivered one child only and 20,584 women who had delivered 2 or more children. Of these, 7339 women reported chronic LBP. The 595 women who were pregnant when information was collected were considered separately, regardless of previous births, with 80 women reporting chronic LBP. Associations with prevalence of chronic LBP were examined by generalised linear modelling with adjustment for potential confounders in a cross-sectional design. Results Women who had delivered one child only showed a higher prevalence of chronic LBP than women with no childbirths (prevalence ratio (PR) 1.11; 95% CI: 1.01–1.22). Among women with one or more childbirths, no overall change in prevalence could be demonstrated with an increasing number of children in analyses adjusted for age at first delivery. In women with at least two childbirths, an age less than 20 years at first childbirth was associated with an increased prevalence of chronic LBP (PR 1.36; 95% CI: 1.25–1.49; compared with age 25–29 years). No association was observed between age at last delivery and chronic LBP. The lowest prevalence of chronic LBP was found among women who were currently pregnant (PR 0.80; 95% CI: 0.63–1.00; compared with women with no childbirths). Conclusions Having experienced at least one childbirth seems to be associated with a higher prevalence of chronic LBP later in life. A young age at first childbirth is also associated with a long-lasting increased prevalence.

Abstract Background Randomised trials on antibiotic treatment for patients with chronic low back pain and vertebral endplate changes visible on MRI (Modic changes) have shown mixed results. A possible explanation might be a real treatment effect in subgroups of the study populations. The purpose of the present study was to explore potential clinical effect modifiers of 3-months oral amoxicillin treatment in patients with chronic low back pain and type I or II Modic changes at the level of a previous lumbar disc herniation. Methods We performed analyses of effect modifiers on data from AIM, a double-blind parallel-group multicentre trial. One hundred eighty patients with chronic low back pain, previous disc herniation, Modic change type I (n = 118) or type II (n = 62) were randomised to 3-months oral treatment with 750 mg amoxicillin (n = 89) or placebo (n = 91) three times daily. The primary outcome was the Roland-Morris Disability Questionnaire (RMDQ) score (possible values 0–24) at 1-year follow-up in the intention-to-treat population. The predefined minimal clinically important between-group mean difference was 4 RMDQ points (not reached in the primary analysis of AIM). Predefined baseline characteristics were analysed as potential effect modifiers, four primary (type I Modic changes, previous disc surgery, positive pain provocation test, high CRP) and five exploratory (disturbed sleep, constant low back pain, short duration of low back pain, younger age, and male) using ANCOVA with interaction terms. Results None of the four primary potential effect modifiers had strong evidence of modifying the treatment effect. In patients younger than 40 years the difference in mean RMDQ score between the treatment groups was − 4.0 (95%CI, − 6.9 to − 1.2), compared to − 0.5 (95%CI, − 2.3 to 1.3) in patients 40 years or older, both in favour of amoxicillin treatment (exploratory analysis). Conclusions We did not find evidence for convincing clinical effect modifiers of antibiotic treatment in patients with chronic low back pain and Modic changes. Our results for younger age in these explorative analyses should not affect clinical treatment decisions without confirmation in future studies. Trial registration ClinicalTrials.gov NCT02323412 , First registered 23 December 2014.

Abstract Background Little research exists on the effectiveness of motivational interviewing (MI) on return to work (RTW) in workers on long term sick leave. The objectives of this study protocol is to describe a randomized controlled trial (RCT) with the objectives to compare the effectiveness and cost-effectiveness of usual case management alone with usual case management plus MI or usual case management plus stratified vocational advice intervention (SVAI), on RTW among people on sick leave due to musculoskeletal (MSK) disorders. Methods A multi-arm RCT with economic evaluation will be conducted in Norway with recruitment of 450 participants aged 18–67 years on 50–100% sick leave for > 7 weeks due to MSK disorders. Participants will be randomized to either usual case management by the Norwegian Labour and Welfare Administration (NAV) alone, usual case management by NAV plus MI, or usual case management by NAV plus SVAI. Trained caseworkers in NAV will give two MI sessions, and physiotherapists will give 1–4 SVAI sessions depending upon risk of long-term sick leave. The primary outcome is the number of sick leave days from randomization to 6 months follow-up. Secondary outcomes are number of sick leave days at 12 months follow-up, time until sustainable RTW (≥4 weeks of at least 50% of their usual working hours) at 12 months, proportions of participants receiving sick leave benefits during 12 months of follow-up, and MSK symptoms influencing health at 12 months. Cost-utility evaluated by the EuroQoL 5D-5L and cost-benefit analyses will be performed. Fidelity of the interventions will be assessed through audio-recordings of approximately 10% of the intervention sessions. Discussion The results from this RCT will inform stakeholders involved in supporting RTW due to MSK disorders such as staff within NAV and primary health care. Trial registration ClinicalTrials.gov ID: NCT03871712 registered March 12th 2020.

Abstract Background Modic Changes (MCs, magnetic resonance imaging (MRI) signal changes in the vertebral bone marrow extending from the vertebral endplate) may represent a subgroup of nonspecific chronic low back pain that could benefit from a specific management. The primary aim was to compare clinical characteristics between patients with type 1 versus type 2 MCs. The secondary aim was to explore associations between clinical characteristics and MC related short tau inversion recovery (STIR) signals. Methods This cross-sectional study used baseline data prospectively collected between 2015 and 2017 on the 180 patients included in the AIM-study (Antibiotics In Modic changes), a randomized controlled trial in a Norwegian hospital out-patient setting of patients with chronic low back pain, a lumbar disc herniation within the last 2 years, low back pain intensity score ≥ 5 (on a 0–10 scale) and current type 1 or type 2 MCs at the previously herniated lumbar disc level. We used prespecified clinical characteristics including self-report measures, physiologic measures and functional measures from clinical history and examination. The diagnostic accuracy of various clinical characteristics to discriminate between patients with type 1 MCs (with or without additional type 2 MCs) and patents with type 2 MCs only (not type 1) were assessed by calculating the area under the receiver-operating curve. We assessed the correlations of clinical characteristics with details of MC related STIR signal increase. Results No clinical characteristic differed between patients with type 1 (n = 118) versus type 2 (but not type 1) (n = 62) MCs. The clinical characteristics showed no/minor differences or no/weak correlations with MC related STIR signal increase. Patients with a positive Springing test (at any lumbar level) had slightly less volume of STIR signal increase than those with a negative test (mean difference 1.3 on a 0–48 scale, 95% CI 0.3 to 2.3). Conclusion Clinical characteristics were similar for patients with type 1 MCs and patients with type 2 MCs, and showed no clinically relevant correlations with MC related STIR signal increase. Trial registration ClinicalTrials.gov NCT02323412 , First registered 23 December 2014

There is limited knowledge on the association between different health complaints and the development of persistent musculoskeletal pain in adolescents. The aims of this study were to assess whether specific health complaints, and an accumulation of health complaints, in the first year of upper-secondary school, were associated with persistent musculoskeletal pain 2 years later. We used data from a population-based cohort study (the Fit Futures Study in Norway), including 551 adolescents without persistent musculoskeletal pain at baseline. The outcome was persistent musculoskeletal pain (≥3 months) 2 years after inclusion. The following self-reported health complaints were investigated as individual exposures at baseline: asthma, allergic rhinitis, atopic eczema, headache, abdominal pain and psychological distress. We also investigated the association between the accumulated number of self-reported health complaints and persistent musculoskeletal pain 2 years later. Logistic regression analyses estimated adjusted odds ratios (ORs) with 95% confidence intervals (CIs). At the 2-year follow-up, 13.8% (95% CI [11.2-16.9]) reported persistent musculoskeletal pain. Baseline abdominal pain was associated with persistent musculoskeletal pain 2 years later (OR 2.33, 95% CI [1.29-4.19], p = 0.01). Our analyses showed no statistically significant associations between asthma, allergic rhinitis, atopic eczema, headache or psychological distress and persistent musculoskeletal pain at the 2-year follow-up. For the accumulated number of health complaints, a higher odds of persistent musculoskeletal pain at the 2-year follow-up was observed for each additional health complaint at baseline (OR 1.33, 95% CI [1.07-1.66], p = 0.01). Health care providers might need to take preventive actions in adolescents with abdominal pain and in adolescents with an accumulation of health complaints to prevent development of persistent musculoskeletal pain. The potential multimorbidity perspective of adolescent musculoskeletal pain is an important topic for future research to understand the underlying patterns of persistent pain conditions in adolescents.

Objectives To describe characteristics of older adults with back pain in primary care, and to assess associations between patient characteristics and type of first primary care provider (general practitioner (GP), physiotherapist (PT) or chiropractor).Design Cross-sectional analysis from the Back Complaints in the Elders-Norway cohort study.Setting Norwegian GP, PT and chiropractic primary care centres.Participants Patients aged ≥55 years seeking Norwegian primary care with a new episode of back pain were invited to participate. Between April 2015 and February 2020, we included 452 patients: 127 first visited a GP, 130 first visited a PT and 195 first visited a chiropractor.Primary and secondary outcome measures For the first objective, the outcome measure was descriptive statistics of patient characteristics, covering the following domains: sociodemographic, general health, current and previous back pain, psychological and clinical factors. For the second objective, first primary care provider was the outcome measure. Associations between patient characteristics and visiting a GP or PT compared with a chiropractor were assessed with multiple multinomial regression analyses.Results Median (IQR) age was 66 (59–72) years. Levels of back-related disability was moderate to severe, with a median (IQR) Roland-Morris Disability Questionnaire (range 0–24) score of 9 (5–13). Recurring episodes were common, 301 (67%) patients had monthly or yearly recurrences. Patients with worse back-related disability, longer duration of symptoms, lower expectations for full recovery and worse physical performance measured with the Back Performance Scale had higher odds of visiting a GP or PT compared with a chiropractor (p

Background Low back pain (LBP) is a leading cause of disability worldwide, but the aetiology remains poorly understood. Finding relevant biomarkers may lead to better understanding of disease mechanisms. Patients with vertebral endplate bone marrow lesions visualised on MRI as Modic changes (MCs) have been proposed as a distinct LBP phenotype, and inflammatory mediators may be involved in the development of MCs.Objectives To identify possible serum biomarkers for LBP in patients with MCs.Methods In this case control study serum levels of 40 cytokines were compared between patients with LBP and MC type 1 (n=46) or type 2 (n=37) and healthy controls (n=50).Results Analyses identified significantly higher levels of six out of 40 cytokines in the MC type 1 group (MC1), and five in the MC type 2 group (MC2) compared with healthy controls. Six cytokines were moderately correlated with pain. Principal component analyses revealed clustering and separation of patients with LBP and controls, capturing 40.8% of the total variance, with 10 cytokines contributing to the separation. Macrophage migration inhibitory factor (MIF) alone accounted for 92% of the total contribution. Further, receiver operating characteristics analysis revealed that MIF showed an acceptable ability to distinguish between patients and controls (area under the curve=0.79).Conclusions These results suggest that cytokines may play a role in LBP with MCs. The clinical significance of the findings is unknown. MIF strongly contributed to clustering of patients with LBP with MCs and controls, and might be a biomarker for MCs. Ultimately, these results may guide future research on novel treatments for this patient group.

Abstract Background The Back Beliefs Questionnaire (BBQ) is a 14-item patient-reported questionnaire that measures attitudes and beliefs about the consequences of back pain. The BBQ has recently been translated into Norwegian, but its psychometric properties have not yet been tested. The aim of this study is to evaluate the reliability and construct validity of the BBQ when used on elderly patients with back pain. Method A prospective cohort study with a test-retest design among 116 elderly patients (> 55 years of age) seeking primary care for a new episode of back pain. Test-retest, standard error of measurement (SEM), minimal detectable change (MDC), internal consistency and construct validity by a priori hypotheses (Spearman’s- and Pearson correlation coefficient) were tested. Results A total of 116 patients, mean age (SD) 67.7 (8.3), were included and 63 patients responded to the test-retest assessment. The mean (SD) BBQ sum scores (range 9–45) were 29.8 (7.0) and 29.2 (6.7) for the test and retest respectively. The test-retest was acceptable with an intraclass correlation coefficient of 0.71 (95% CI, 0.54–0.82), SEM was 3.8 and MDC 10.5. Internal consistency with Cronbach’s alpha was good (0.82) and acceptable construct validity was supported by the confirmation of 75% of the a priori hypotheses. Conclusion The Norwegian version of the BBQ demonstrated acceptable test-retest reliability and good construct validity and can be used to assess pessimistic beliefs in elderly patients with back pain.

Abstract Background Lateral epicondylitis (LE) is a challenging condition for clinicians, and research has yet not proven the superiority of one specific treatment approach. However, manual therapy (elbow mobilization) in addition to eccentric exercise has been found to be superior to exercise alone. As well, acupuncture is effective in short-term pain relief when compared with sham treatment, but there is little knowledge on the comparative effectiveness of manual therapy and acupuncture treatment of LE in terms of pain relief. The primary objective of this pilot trial was to assess the feasibility (retention and adherence rates) of performing a randomized controlled trial (RCT) to explore the clinical effectiveness of acupuncture and manual therapy treatment of LE. Methods This pilot trial took place in an outpatient interdisciplinary institute of sports medicine and rehabilitation in Oslo, Norway. Thirty-six adults with clinically diagnosed LE were randomly allocated into one of three groups: eccentric exercise alone, eccentric exercise plus acupuncture, or eccentric exercise plus manual therapy for a 12-week treatment period. Primary outcomes were patient retention and adherence rates. Secondary outcomes included patient-reported pain (NRS), level of disability (Quick-DASH), and participant’s satisfaction with treatment and global perceived effect. Results Nine (69%) patients in the acupuncture group completed the 1-year follow-up, compared to eight (67%) in the manual therapy group and five (45%) in exercise alone. Our goal was to demonstrate a retention rate above 80% to avoid serious threats to validity, but the result was lower than expected. The majority of participants (64%) in both treatment groups received only three-treatment sessions; the reasons included non-attendance or recovery from pain. Secondary outcomes support the rationale for conduction of an RCT. There were no adverse advents related to study participation. Conclusions Based on differences in pain relief between groups, patient retention, and adherence rates, an RCT seems to be feasible to assess treatment effectiveness more precisely. In a future definitive trial, greater dropout may be reduced by maintaining contact with the participants in the exercise alone group throughout the intervention, and objective assessments might be considered. Trial registration ClinicalTrials.gov, NCT02321696

Abstract Background Assessment of outcomes for spinal surgeries is challenging, and an ideal measurement that reflects all aspects of importance for the patients does not exist. Oswestry Disability Index (ODI), EuroQol (EQ-5D) and Numeric Rating Scales (NRS) for leg pain and for back pain are commonly used patients reported outcome measurements (PROMs). Reporting the proportion of individuals with an outcome of clinical importance is recommended. Knowledge of the ability of PROMs to identify clearly improved patients is essential. The purpose of this study was to search cut-off criteria for PROMs that best reflect an improvement considered by the patients to be of clinical importance. Methods The Global Perceived Effect scale was utilized to evaluate a clinically important outcome 12 months after surgery. The cut-offs for the PROMs that most accurately distinguish those who reported ‘completely recovered’ or ‘much improved’ from those who reported ‘slightly improved’, unchanged’, ‘slightly worse’, ‘much worse’, or ‘worse than ever’ were estimated. For each PROM, we evaluated three candidate response parameters: the (raw) follow-up score, the (numerical) change score, and the percentage change score. Results We analysed 3859 patients with Lumbar Spinal Stenosis [(LSS); mean age 66; female gender 50%] and 617 patients with Lumbar Degenerative Spondylolisthesis [(LDS); mean age 67; 72% female gender]. The accuracy of identifying ‘completely recovered’ and ‘much better’ patients was generally high, but lower for EQ-5D than for the other PROMs. For all PROMs the accuracy was lower for the change score than for the follow-up score and the percentage change score, especially among patients with low and high PROM scores at baseline. The optimal threshold for a clinically important outcome was ≤24 for ODI, ≥0.69 for EQ-5D, ≤3 for NRS leg pain, and ≤ 4 for NRS back pain, and, for the percentage change score, ≥30% for ODI, ≥40% for NRS leg pain, and ≥ 33% for NRS back pain. The estimated cut-offs were similar for LSS and for LDS. Conclusion For estimating a ‘success’ rate assessed by a PROM, we recommend using the follow-up score or the percentage change score. These scores reflected a clinically important outcome better than the change score.

Abstract Background Fusion in addition to decompression has become the standard treatment for lumbar spinal stenosis with degenerative spondylolisthesis (DS). The evidence for performing fusion among these patients is conflicting and there is a need for further investigation through studies of high quality. The present protocol describes an ongoing study with the primary aim of comparing the outcome between decompression alone and decompression with instrumented fusion. The secondary aim is to investigate whether predictors can be used to choose the best treatment for an individual. The trial, named the NORDSTEN-DS trial, is one of three studies in the Norwegian Degenerative Spinal Stenosis (NORDSTEN) study. Methods The NORDSTEN-DS trial is a block-randomized, controlled, multicenter, non-inferiority study with two parallel groups. The surgeons at the 15 participating hospitals decide whether a patient is eligible or not according to the inclusion and exclusion criteria. Participating patients are randomized to either a midline preserving decompression or a decompression followed by an instrumental fusion. Primary endpoint is the percentage of patients with an improvement in Oswestry Disability Index version 2.0 of more than 30% from baseline to 2-year follow-up. Secondary outcome measurements are the Zürich Claudication Questionnaire, Numeric Rating Scale for back and leg pain, Euroqol 5 dimensions questionnaire, Global perceived effect scale, complications and several radiological parameters. Analysis and interpretation of results will also be conducted after 5 and 10 years. Conclusion The NORDSTEN/DS trial has the potential to provide Level 1 evidence of whether decompression alone should be advocated as the preferred method or not. Further on the study will investigate whether predictors exist and if they can be used to make the appropriate choice for surgical treatment for this patient group. Trial registration ClinicalTrials.gov Identifier: NCT02051374. First Posted: January 31, 2014. Last Update Posted: February 14, 2018.

Abstract Background Spinal stenosis is a clinical diagnosis in which the main symptom is pain radiating to the lower extremities, or neurogenic claudication. Radiological spinal stenosis is commonly observed in the population and it is debated whether patients with no lower extremity pain should be labelled as having spinal stenosis. However, these patients is found in the Norwegian Registry for Spine Surgery, the main object of the present study was to compare the clinical outcomes after decompressive surgery in patients with insignificant lower extremity pain, with those with more severe pain. Methods This study is based on data from the Norwegian Registry for Spine Surgery (NORspine). Patients who had decompressive surgery in the period from 7/1–2007 to 11/3–2013 at 31 hospitals were included. The patients was divided into four groups based on preoperative Numeric Rating Scale (NRS)-score for lower extremity pain. Patients in group 1 had insignificant pain, group 2 had mild or moderate pain, group 3 severe pain and group 4 extremely severe pain. The primary outcome was change in the Oswestry Disability Index (ODI). Successfully treated patients were defined as patients reporting at least 30% reduction of baseline ODI, and the number of successfully treated patients in each group were recorded. Results In total, 3181 patients were eligible; 154 patients in group 1; 753 in group 2; 1766 in group 3; and 528 in group 4. Group 1 had significantly less improvement from baseline in all the clinical scores 12 months after surgery compared to the other groups. However, with a mean reduction of 8 ODI points and 56% of patients showing a reduction of at least 30% in their ODI score, the proportion of patients defined as successfully treated in group 1, was not significantly different from that of other groups. Conclusion This national register study shows that patients with insignificant lower extremity pain had less improvement in primary and secondary outcome parameters from baseline to follow-up compared to patients with more severe lower extremity pain.

The objective was to investigate risk factors and risk profiles associated with neck pain in young adults using longitudinal data from the North-Trøndelag Health Study (HUNT). Risk factors were collected from adolescents (13-19 years of age), and neck pain was measured 11 years later. The sample was divided into two: Sample I included all participants (n = 1433), and Sample II (n = 832) included only participants who reported no neck/shoulder pain in adolescence. In multiple regression analyses in Sample I, female sex (OR = 1.9, 95% CI [1.3-2.9]), low physical activity level (OR = 1.6, 95% CI [1.0-2.5]), loneliness (OR = 2.0, 95% CI [1.2-3.5]), headache/migraine (OR = 1.7, 95% CI [1.2-2.6]), back pain (OR = 1.5, 95% CI [1.0-2.4]) and neck/shoulder pain (OR = 2.0, 95% [CI 1.3-3.0]) were associated with neck pain at the 11-year follow-up. Those with a risk profile including all these risk factors had the highest probability of neck pain of 67% in girls and 50% in boys. In Sample II, multiple regression analyses revealed that female sex (OR = 2.2, 95% CI [1.3-3.7]) and perceived low family income (OR = 2.4, 95% CI [1.1-5.1]) were associated with neck pain at the 11-year follow-up. Girls and boys with a perceived low family income had a 29% and 17% higher probability of neck pain than adolescents with a perceived high family income. The risk profiles in both samples showed that co-occurrence of risk factors, such as headache/migraine, neck/shoulder pain, back pain, low physical activity level, loneliness, and perceived low family income cumulatively increased the probability of neck pain in young adulthood. These results underline the importance of taking a broad perspective when studying, treating, and preventing neck pain in adolescents.

Abstract Background Cluster randomized controlled trials are often used in research in primary care but creates challenges regarding biases and confounders. We recently presented a study on low back pain from primary care in Norway with equal effects in the intervention and the control group. In order to understand the specific mechanisms that may produce biases in a cluster randomized trial we conducted a focus group study among the participating health care providers. The aim of this study was to understand how the participating providers themselves influenced on the study and thereby possibly on the results of the cluster randomized controlled trial. Methods The providers were invited to share their experiences from their participation in the COPE study, from recruitment of patients to accomplishment of either the intervention or control consultations. Six clinicians from the intervention group and four from the control group took part in the focus group interviews. The group discussions focused on feasibility of the study in primary care and particularly on identifying potential biases and confounders in the study. The audio-recorded interviews were transcribed verbatim and analyzed according to a systematic text condensation. The themes for the analysis emerged from the group discussions. Results A personal interest for back pain, logistic factors at the clinics and an assessment of the patients’ capacity to accomplish the study prior to their recruitment was reported. The providers were allowed to provide additional therapy to the intervention and it turned out that some of these could be regarded as opposed to the messages of the intervention. The providers seemed to select different items from the educational package according to personal beliefs and their perception of the patients’ acceptance. Conclusion The study disclosed several potential biases to the COPE study which may have impacted on the study results. Awareness of these is highly important when planning and conducting a cluster randomized controlled trial. Procedures in the recruitment of both providers and patients seem to be key factors and the providers should be aware of their role in a scientific study in order to standardize the provision of the intervention.

Abstract Background A previous randomised controlled trial (RCT) of patients with chronic low back pain (LBP) and vertebral bone marrow (Modic) changes (MCs) on magnetic resonance imaging (MRI), reported that a 3-month, high-dose course of antibiotics had a better effect than placebo at 12 months’ follow-up. The present study examines the effects of antibiotic treatment in chronic LBP patients with MCs at the level of a lumbar disc herniation, similar to the previous study. It also aims to assess the cost-effectiveness of the treatment, refine the MRI assessment of MCs, and further evaluate the impact of the treatment and the pathogenesis of MCs by studying genetic variability and the gene and protein expression of inflammatory biomarkers. Methods/design A double-blinded RCT is conducted at six hospitals in Norway, comparing orally administered amoxicillin 750 mg, or placebo three times a day, over a period of 100 days in patients with chronic LBP and type I or II MCs at the level of a MRI-confirmed lumbar disc herniation within the preceding 2 years. The inclusion will be stopped when at least 80 patients are included in each of the two MC type groups. In each MC type group, the study is designed to detect (β = 0.1, α = 0.05) a mean difference of 4 (standard deviation 5) in the Roland Morris Disability Questionnaire score between the two treatment groups (amoxicillin or placebo) at 1-year follow-up. The study includes cost-effectiveness measures. Blood samples are assessed for security measures and for possible inflammatory mediators and biomarkers at different time points. MCs are evaluated on MRI at baseline and after 12 months. A blinded intention-to-treat analysis of treatment effects will be performed in the total sample and in each MC type group. Discussion To ensure the appropriate use of antibiotic treatment, its effect in chronic LBP patients with MCs should be re-assessed. This study will investigate the effects and cost-effectiveness of amoxicillin in patients with chronic LBP and MCs at the level of a disc herniation. The study may also help to refine imaging and characterise the biomarkers of MCs. Trial registration ClinicalTrials.gov, ID: NCT02323412 . Registered on 21 November 2014.

Abstract Background To study whether thyroid function was associated with risk of hip or knee replacement due to primary osteoarthritis. Methods In a prospective cohort study, data from the second and third survey of the Nord-Trøndelag Health Study were linked to the Norwegian Arthroplasty Register in order to identify total hip or knee replacement as a result of primary osteoarthritis. Results Among 37 891 participants without previously known thyroid disease we recorded 978 total hip replacements (THRs) and 538 total knee replacements (TKRs) during a median follow-up time of 15.7 years. The analyses were adjusted for sex, age, BMI (body mass index), smoking, physical activity and diabetes. We did not find any association between TSH (thyroid stimulating hormone) and THR or TKR due to osteoarthritis. Neither were changes in TSH over time, or overt hypo- or hyperthyroidism, associated with incidence of THR or TKR. Conclusion No association was found between thyroid function and hip or knee joint replacement due to osteoarthritis.

Abstract Background Evidence is lacking on whether fat infiltration in the multifidus muscles affects outcomes after total disc replacement (TDR) surgery and if it develops after surgery. The aims of this study were 1) to investigate whether pre-treatment multifidus muscle fat infiltration predicts outcome 2 years after treatment with TDR surgery or multidisciplinary rehabilitation, and 2) to compare changes in multifidus muscle fat infiltration from pre-treatment to 2-year follow-up between the two treatment groups. Methods The study is secondary analysis of data from a trial with 2-year follow-up of patients with chronic low back pain (LBP) and degenerative disc randomized to TDR surgery or multidisciplinary rehabilitation. We analyzed (aim 1) patients with both magnetic resonance imaging (MRI) at pre-treatment and valid data on outcome measures at 2-year follow-up (predictor analysis), and (aim 2) patients with MRI at both pre-treatment and 2-year follow-up. Outcome measures were visual analogue scale (VAS) for LBP, Oswestry Disability Index (ODI), work status and muscle fat infiltration on MRI. Patients with pre-treatment MRI and 2-year outcome data on VAS for LBP (n = 144), ODI (n = 147), and work status (n = 137) were analyzed for prediction purposes. At 2-year follow-up, 126 patients had another MRI scan, and change in muscle fat infiltration was compared between the two treatment groups. Three radiologists visually quantified multifidus muscle fat in the three lower lumbar levels on MRI as 50% (grade 2) of the muscle cross-section containing fat. Regression analysis and a mid-P exact test were carried out. Results Grade 0 pre-treatment multifidus muscle fat predicted better clinical results at 2-year follow-up after TDR surgery (all outcomes) but not after rehabilitation. At 2-year follow-up, increased fat infiltration was more common in the surgery group (intention-to-treat p = 0.03, per protocol p = 0.08) where it was related to worse pain and ODI. Conclusions Patients with less fat infiltration of multifidus muscles before TDR surgery had better outcomes at 2-year follow-up, but findings also indicated a negative influence of TDR surgery on back muscle morphology in some patients. The rehabilitation group maintained their muscular morphology and were unaffected by pre-treatment multifidus muscle fat. Trial registration NCT 00394732 (retrospectively registered October 31, 2006).

Objectives Knowledge of how physical activity (PA) and sport participation are related to mental health throughout adolescence is scarce. Our objective was to describe PA levels and sport participation in a population-based sample of adolescents, and to explore how they relate to mental health in different age groups.Design A population-based cross-sectional study.Setting and participants The adolescent part of the Nord-Trøndelag Health Study, a Norwegian population-based health survey, conducted from 2006 to 2008. Of 10 464 invited participants (age 13–19 years), 7619 (73%) participated, of whom 3785 (50%) were boys.Outcome measures Mental health outcomes included psychological distress assessed using a short version of the Hopkins Symptom Check List Five items, self-esteem assessed using a short version of the Rosenberg Self-Esteem Scale and life satisfaction assessed with a single-item satisfaction with life measure.Method Logistic regression models were used to estimate the likelihood of psychological distress, low self-esteem and low life satisfaction, according to self-reported PA level and type of sport participation, stratified by gender and school level (junior vs senior high school).Results Fewer senior high school students participated in team sports compared with junior high school students (p

Background Studies from different Western countries have reported a rapid increase in spinal surgery rates, an increase that exceeds by far the growing incidence rates of spinal disorders in the general population. There are few studies covering all lumbar spine surgery and no previous studies from Norway.Objectives The purpose of this study was to investigate trends in all lumbar spine surgery in Norway over 15 years, including length of hospital stay, and rates of complications and reoperations.Design A longitudinal observational study over 15 years using hospital patient administrative data and sociodemographic data from the National Registry in Norway.Setting and participants Patients aged ≥18 years discharged from Norwegian public hospitals between 1999 and 2013.Outcome measures Annual rates of simple (microsurgical discectomy, decompression) and complex surgical procedures (fusion, disc prosthesis) in the lumbar spine.Results The rate of lumbar spine surgery increased by 54%, from 78 (95% CI (75 to 80)) to 120 (107 to 113) per 100 000, from 1999 to 2013. More men had simple surgery whereas more women had complex surgery. Among elderly people over 75 years, lumbar surgery increased by a factor of five during the 15-year period. The rates of complications were low, but increased from 0.7% in 1999 to 2.4% in 2013.Conclusions There was a substantial increase in lumbar spine surgery in Norway from 1999 to 2013, similar to trends in other Western world countries. The rise in lumbar surgery among elderly people represents a significant workload and challenge for health services, given our aging population.

BACKGROUND:Previous systematic reviews have reported positive associations between Modic changes (MCs) and low back pain (LBP), but due to their narrow scope and new primary studies, there is a need for a comprehensive systematic review. Our objectives were to investigate if MCs are associated with non-specific LBP and/or activity limitation and if such associations are modified by other factors. METHODS:A protocol for this review was registered at PROSPERO prior to commencing the work (PROSPERO record: CRD42015017350). The MEDLINE, CINAHL and EMBASE databases were searched for relevant studies from first record to June 15th 2016. Prospective or retrospective cross-sectional cohort studies and case-control studies including people of all ages from general, working and clinical study populations were eligible for inclusion. Risk of bias assessment and data extraction for associations and potential modifiers were completed independently by pairs of reviewers. Meta-analysis was performed for homogeneous studies and presented as odds ratios (OR) with 95% CI. RESULTS:In all, 5210 citations were identified and 31 studies were included. One study had low risk of bias. Fifteen studies (48%) reported statistically significant positive associations between MCs and LBP and one study found a statistically significant negative association. Meta-analysis performed for studies using concordant pain with provocative discography as the clinical outcome resulted in an OR of 4.01 (1.52-10.61). One of seven studies reported a statistically significant positive association between MCs and activity limitation. Lumbar disc level and disc degeneration were found to modify the association between MCs and LBP. CONCLUSIONS:The results from this comprehensive systematic review indicate that the associations between MCs and LBP-related outcomes are inconsistent. The high risk of bias and the heterogeneity in terms of study samples, clinical outcomes and prevalence estimates of MCs and LBP may explain these findings. It is likely that new studies with low risk of bias will affect the direction and strength of these associations.

To investigate the total effect of smoking on total hip or knee replacement (THR/TKR) due to primary osteoarthritis (OA) and to quantify the indirect effect of smoking through body mass index (BMI). Participants from the Nord-Trøndelag Health Study (the HUNT Study) were linked to the Norwegian Arthroplasty Register to detect the first THR or TKR due to primary OA. A mediation analysis was used to decompose the total effect of smoking into a direct and indirect effect. BMI was considered a mediator in the analysis. All effects were estimated as hazard ratios (HRs) with 95% confidence intervals (CIs). The indirect effect of smoking mediated through BMI was expressed as a percentage (proportion*100). In total 55 188 participants were followed up during 17.2 years (median). We identified 1322 THRs and 754 TKRs. For men, the total effect of current vs. never smoking revealed a decreased risk of THR (HR 0.59, 95% CI 0.46-0.76) and TKR (HR 0.47, 95% CI 0.32-0.66). For women, current smoking increased the risk of THR (HR 1.34, 95% CI 1.11-1.60). For men, 6% and 7% of the risk reduction for THR and TKR, respectively, was mediated by BMI. We found a negative association between smoking and THR or TKR for men. On the contrary, smoking was associated with increased risk of THR for women. Most of the effect of smoking on joint replacement risk remained unexplained by BMI.