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AIMS: To compare the results of a traditional approach using standard regression for the analysis of data from a prospective cohort study with the results of generalised estimating equations (GEE) analysis.METHODS: The research was part of a three year prospective cohort study on work related risk factors for low back pain. The study population consisted of a cohort of 1192 workers with no low back pain at baseline. Information on work related physical and psychosocial factors and the occurrence of low back pain was obtained by means of questionnaires at baseline and at the three annual follow up measurements. In a traditional standard logistic regression model, physical and psychosocial risk factors at baseline were related to the cumulative incidence of low back pain during the three year follow up period. In a GEE logistic model, repeated measurements of the physical and psychosocial risk factors were related to low back pain reported at one measurement point later.RESULTS: The traditional standard regression model showed a significant effect of flexion and/or rotation of the upper part of the body (OR = 1.8; 95% CI: 1.2 to 3.0), but not of moving heavy loads (OR = 1.4; 95% CI: 0.7 to 3.1). The GEE model showed a significant effect of both flexion and/or rotation of the upper part of the body (OR = 2.2; 95% CI: 1.5 to 3.3) and moving heavy loads (OR = 1.5; 95% CI: 1.0 to 2.4). No significant associations with low back pain were found for the psychosocial work characteristics with either method, but the GEE model showed weaker odds ratios for these variables than the traditional standard regression model.CONCLUSIONS: Results show that there are differences between the two analytical approaches in both the magnitude and the precision of the observed odds ratios.

Background Knowledge of risk factors of future pain and physical functioning can be used to inform patients with hip osteoarthritis (OA) on the likely course of their condition and to adapt treatment according to the prognosis. Objectives To systematically summarise the literature on (1) the course of pain and physical functioning and on (2) prognostic factors of future pain and physical functioning in patients with OA of the hip. Methods A search was conducted in PubMed, CINAHL, Embase, Psych-INFO, and SPORTDiscus up to January 2014. Relevant study characteristics were reviewed. Studies were scored for their quality and a qualitative data synthesis was performed. Results Of the twelve included studies, seven were of high quality. No evidence was found on the course of hip pain, due to a lack of high quality studies. Because of high heterogeneity within studies (reflected by large standard deviations of change scores), the course of physical functioning was interpreted to be indistinct. Clinical characteristics (additional presence of knee OA and higher morbidity count), health behavior factors (no supervised exercise and a lower level of physical activity) and other patient characteristics (lower level of education) (weak evidence) were found to predict future pain (weak evidence). Higher morbidity count and lower vitality were found to predict deterioration in physical functioning (strong evidence). Conclusions The course of physical functioning was found to be highly variable. Several clinical characteristics, health and psychosocial factors prognosticate deterioration of pain and physical functioning in patients with hip OA. These findings may guide future research that aims to identify prognostically homogeneous subgroups of hip OA patients. To our knowledge, this is the first systematic review on prognostic factors for deterioration of pain and physical functioning in patients with hip OA. Disclosure of Interest None declared

Background The natural course of physical functioning in knee and/or hipOA is highly variable; some patients remain stable, while others improve or worsen. Knowledge on prognostic risk factors related to physical functioning are used to adapt interventions. Objectives (1) To systematically summarize the literature from March 2005 to January 2013 on the course of physical functioning and pain in patients with OA of the knee or hip and (2) to provide an overview of prognostic factors of physical functioning and future pain for these patients. Methods A search was conducted in PubMed, CINAHL, Embase and Psych-INFO in January 2013. Eligible studies were prospective cohort studies that included participants with knee or hip OA diagnosed with radiographically and/or clinically diagnosed knee or hip OA, or participants with knee or hip pain who were likely to have OA. Outcome measures were measurements that evaluated physical functioning and pain. The included articles were assessed for bias and the results were summarized according to best evidence synthesis. Results Of the 9068 studies that were found, 27 articles were included. In patients with knee OA, the average course of physical functioning varied between studies (inconsistent evidence). The same was found for the average course of knee pain in studies with a follow up period shorter than three years. In addition, in patients with hip OA the average course of physical functioning in studies with a follow up period shorter than three years was found to be stable (strong evidence). Because only one study examined the course of physical functioning over a period longer than three years, weak evidence was found for a stable course over 5 years. With regard to prognostic factors, in patients with knee OA strong evidence was found for various prognostic factors for future deterioration in physical functioning i.e. older age, a low to middle education level, higher body mass index, high morbidity count, use of pain medication, greater difficulties with physical functioning at baseline, lower knee extension strength, higher pain intensity, patella-femoral joint compression, lower walking ability, poor mental health and a low vitality. With regard to predictors for future knee pain, a longer symptom duration, bilateral knee symptoms and a higher level of pain at baseline were found to predict future pain in patients with knee OA (strong evidence). In hip OA strong evidence was found that a high morbidity count and a low vitality increase the likelihood of deterioration of physical functioning. No publications were found on prognostic factors for future pain. Conclusions The average course of physical functioning and pain in patients with knee OA was found to be variable between studies. In hip OA, the long-term course of physical functioning was found to be stable. In comparison to a previous review stronger evidence was found for a number of variables to be prognostic factors of physical functioning and pain, including demographic factors, clinical factors, knee characteristics and psychosocial factors. Disclosure of Interest None declared DOI 10.1136/annrheumdis-2014-eular.2830

Background In the assessment of chronic pain patients it is important to measure pain behavior and pain interference. The National Institutes of Health9s Patient-Reported Outcomes Measurement Information System (PROMIS) initiative developed item banks for measuring pain behavior and pain interference. These PROMIS item banks were translated into Dutch-Flemish language according to the FACIT methodology 1 . Objectives The aim of current study was to validate the Dutch-Flemish translation of the PROMIS pain behavior item bank (DF-PROMIS-PB) and the Dutch-Flemish PROMIS pain interference item bank (DF-PROMIS-PI) in patients with chronic pain. Methods A paper-and-pencil or web-based survey, including the full DF-PROMIS-PB (39 items, 6-point Likert scale) and DF-PROMIS-PI (41 items, 5-point Likert scale), was completed by 1046 chronic pain patients referred to an outpatient secondary care center for rheumatology and rehabilitation in the Netherlands. One-dimensionality was evaluated by one-factor confirmatory factor analysis. With the future strategy to develop computer adaptive tests (CAT), item response theory (IRT) models were used to evaluate the item characteristics of the two item banks. A graded item response model (GRM) was fitted and Differential Item Functioning (DIF) was evaluated for e.g. language (Dutch vs. English), by ordinal regression models. Furthermore, construct validity was studied. Results DF-PROMIS-PB and DF-PROMIS-PI demonstrated good fit to a one-dimensional model (CFI=0.963; 0.988 resp. and TLI=0.961; 0.987 resp). The first factor accounted for 42% (DF-PROMIS-PB) and 66% (DF-PROMIS-PI) of the questionnaire variance. The results showed acceptable testinformation (SE Conclusions The DF-PROMIS-PB and the DF-PROMIS-PI fit a GRM and demonstrate good coverage across the range of the pain behavior and pain interference domain. Nearly all Dutch item parameters match the American item parameters and likely Dutch-specific item calibrations are not needed. The DF-PROMIS-PB and DF-PROMIS-PI can be used to develop a CAT. References Terwee CB, Roorda LD, de Vet HCW, Dekker J, Westhovens R, van Leeuwen J, Cella D, Correia H, Arnold B, Perez B, Boers M. Dutch-Flemish translation of 17 item banks from the Patient Reported Outcomes Measurement Information System (PROMIS). Quality of Life Research in press. Disclosure of Interest : None declared DOI 10.1136/annrheumdis-2014-eular.1723

Background In the assessment of chronic pain patients it is important to measure physical functioning. The National Institutes of Health9s Patient-Reported Outcomes Measurement Information System (PROMIS) initiative developed an item bank for measuring physical functioning. This PROMIS physical functioning item bank was translated into Dutch-Flemish language according to the FACIT methodology 1 . Objectives The aim of current study was to validate the Dutch-Flemish translation of the PROMIS physical functioning item bank (DF-PROMIS-PF) in patients with chronic pain. Methods A paper-and-pencil or web-based survey including the full DF-PROMIS-PF (124 items), was completed by 857 chronic pain patients (77% female, mean age 49y) referred to an outpatient secondary care center for rheumatology and rehabilitation in the Netherlands. One-dimensionality was evaluated by one-factor confirmatory factor analysis. With the future strategy to develop computer adaptive tests (CAT), item response theory (IRT) models were used to evaluate the item characteristics of the two item banks. A graded item response model (GRM) was fitted and Differential Item Functioning (DIF) was evaluated for e.g. language (Dutch vs. English), by ordinal regression models. Furthermore, construct validity was studied. Results Through computer technical limitation, the item bank was separated during statistical analysis into DF-PROMIS-PF A (51 PFA-items) and DF-PROMIS-PF BC (45 PF B - and 28 PF C -items). These interim analysis showed that the DF-PROMIS-PF A and DF-PROMIS-PF BC demonstrated good fit to a one-dimensional model (both CFI=0.976 and TLI=0.975). The first factor accounted for 57% of the questionnaire variance. The results showed acceptable testinformation (SE A and between -1.6 and 4 for DF-PROMIS-PF BC . 103 out of 1275 (8%) DF-PROMIS-PF A item pairs and 130 out of 1431 (9%) DF-PROMIS-PF BC item pairs were marked as possibly locally dependent. The items demonstrated no DIF with respect to survey version. DIF was present with respect to gender (2 items), age (4 items) and language (11 items). However, the impact of DIF on the total item scores was minimal. Conclusions The first results indicate that the DF-PROMIS-PF fits a GRM and demonstrates good coverage across the range of the physical functioning domain. Nearly all Dutch item parameters match the American item parameters and likely Dutch-specific item calibrations are not needed. The DF-PROMIS-PF can be used to develop a CAT. References Terwee CB, Roorda LD, de Vet HCW, Dekker J, Westhovens R, van Leeuwen J, Cella D, Correia H, Arnold B, Perez B, Boers M. Dutch-Flemish translation of 17 item banks from the Patient Reported Outcomes Measurement Information System (PROMIS). Quality of Life Research in press. Disclosure of Interest : None declared DOI 10.1136/annrheumdis-2014-eular.1721

Background Self-report questionnaires and performance-based tests correlate moderately in measuring activity limitations, indicating that they are measuring different aspects. Self-reports measures mainly the patients’ perception which may lead to cross-cultural differences. Performance-based tests measure an artificial situation and might be a burden for patients, requires physical presence and is time- and money consuming. An alternative method is a computerized animated activity questionnaire (AAQ). Besides being a solution for the abovementioned disadvantages the AAQ do not need reading ability and translation for international use. Objectives To develop a computerized AAQ, a new method to assess activity limitations in patients with hip and knee osteoarthritis (OA). Methods First the construct to be measured is described. For content validity the ICF core set for hip and knee OA and self-report questionnaires were consulted. In addition two patient focus group sessions were performed to identify the most limited activities, included the different executions of those activities. Subsequently a specialized company videotaped the executions of the activities (performed by physical therapists as actors) using motion capture and transformed the videos into animations. A virtual environment was created in the animation in order to imitate a standard real life situation as much as possible. A computerized questionnaire was composed. Results Seventeen basic daily activities were selected. For each activity 3 to 5 levels of executions were filmed. Subsequently video animations were produced of all the levels of execution of the 17 activities. In the final AAQ patients are asked to choose the video that best matches their own performance. Conclusions A new Patient Reported Outcome method to measure activity limitations in patients with hip and knee OA was developed: the computerized AAQ. The AAQ shows animations of basic daily activities in virtual, real life situations. The AAQ can minimize the patients’ perception, is less burdensome and save time/money. Furthermore no reading ability and translation is needed. On-going research focuses on assessing (cross-cultural) validity and reliability. Funding This project is funded by the EULAR Grant for research on Patient Reported Outcome. Disclosure of Interest None Declared

Clinicians are interested in observer variation in terms of the probability of other raters (interobserver) or themselves (intraobserver) obtaining the same answer. Cohen's κ is commonly used in the medical literature to express such agreement in categorical outcomes. The value of Cohen's κ, however, is not sufficiently informative because it is a relative measure, while the clinician's question of observer variation calls for an absolute measure. Using an example in which the observed agreement and κ lead to different conclusions, we illustrate that percentage agreement is an absolute measure (a measure of agreement) and that κ is a relative measure (a measure of reliability). For the data to be useful for clinicians, measures of agreement should be used. The proportion of specific agreement, expressing the agreement separately for the positive and the negative ratings, is the most appropriate measure for conveying the relevant information in a 2 × 2 table and is most informative for clinicians.