The patient-reported outcomes measurement information systems (PROMIS®) physical function and its derivative measures in adults: a systematic review of content validity.

PURPOSE: This study aims to systematically review and critically appraise the content validity of the adult versions of the Patient-Reported Outcomes Measurement Information System Physical Function (PROMIS-PF) item bank and its derivative measures in any adult population. METHODS: MEDLINE and EMBASE were searched in October 2021 for studies on measurement properties of PROMIS-PF measures in an adult population. Studies were included if the study described the development of a PROMIS-PF measure or investigated its relevance, comprehensiveness, or comprehensibility. Assessment of the methodological quality of eligible studies, rating of results, and summarizing evidence was performed following the COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) methodology for assessing content validity. A modified GRADE approach was used to determine the level of evidence. RESULTS: Three development studies and eight studies on the content validity of one or more of the PROMIS-PF measures were identified. The methodological quality of most studies was rated doubtful. There was low to high level evidence for sufficient relevance, comprehensiveness, and comprehensibility of most PROMIS-PF measures for healthy seniors and various disease populations. We found low to moderate level evidence for insufficient relevance of PROMIS-PF measures for patients with conditions that affected only one body part, and insufficient comprehensibility of the PROMIS-PF measures for minority elderly. CONCLUSION: Most PROMIS-PF measures demonstrate sufficient content validity in healthy seniors and various disease populations. However, the quality of this evidence is generally low to moderate, due to limitations in the methodological quality of the studies.

Dutch-Flemish translation and cross-cultural adaption of the Spinal Cord Injury-Quality of Life (SCI-QOL) short forms.

PURPOSE: A spinal cord injury (SCI) has a large impact on a person's physical, psychological, and social health. Previous studies focused on physical recovery in patients with SCI and assessed their health-related quality of life (HRQOL) with general questionnaires, which often contain irrelevant questions. The SCI-QOL questionnaire was developed to specifically assess the HRQOL of the SCI population. A comprehensive translation and cross-cultural adaptation are required to use this questionnaire in the Netherlands and Flanders, Belgium. METHODS: All 23 short forms of the SCI-QOL for adults were translated from English into Dutch-Flemish using the Functional Assessment of Chronic Illness Therapy translation methodology, with a cognitive debriefing being performed with 10 patients with SCI and 10 persons from the general population. RESULTS: The Dutch-Flemish PROMIS group previously translated 46 of the 207 items in the 23 short forms. Here, we achieved an acceptable translation of the other 161 items. A single Dutch-Flemish translation was obtained for 20 short forms, while separate Dutch and Flemish translations were necessary for the short forms Ambulation, Manual Wheelchair, and Stigma. CONCLUSION: The Dutch-Flemish translation of the SCI-QOL is now available for clinical and research purposes. Future studies should focus on the psychometric properties of this cross-culturally adapted version.

Reducing the Number of Test Items of the Action Research Arm Test Poststroke: A Decision Tree Analysis✰.

OBJECTIVE: The present study aimed to create a shorter version of the Action Research Arm Test (ARAT) without compromising its measurement properties. DESIGN: Secondary analysis of stroke recovery cohorts that used the ARAT to measure upper limb impairment. SETTING: Rehabilitation centers. PARTICIPANTS: Patients with stroke from 5 different stroke recovery cohorts (N=1425). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: A decision tree version of the ARAT (ARAT-DT) was developed using chi-square automated interaction detection. In an independent validation subset, criterion validity, agreement of ARAT-DT with original ARAT scores and score categories, and construct validity with the Fugl-Meyer Upper Extremity Scale score were determined. RESULTS: In total, 3738 ARAT measurements were available involving 1425 subjects. Chi-square automated interaction detection analysis in the development subset (n=2803) revealed an optimized decision tree with a maximum of 4 consecutive items. In the validation data set (n=935), the ARAT-DT differed by a mean of 0.19 points (0.3% of the total scale) from the original ARAT scores (limits of agreement=-5.67 to 6.05). The ARAT-DT demonstrated excellent criterion validity with the original ARAT scores (intraclass correlation coefficient=0.99 and ρ=0.99) and scoring categories (κw=0.97). The ARAT-DT showed very good construct validity with the Fugl-Meyer Upper Extremity Scale (ρ=0.92). CONCLUSION: A decision tree version of the ARAT was developed, reducing the maximum number of items necessary for ARAT administration from 19 to 4. The scores produced by the decision tree had excellent criterion validity with original ARAT scores.

Determinants of pain and activity limitations in foot osteoarthritis: An exploratory cross-sectional study in the Amsterdam-foot cohort.

Objectives: Osteoarthritis (OA) of the foot-ankle complex is understudied. Understanding determinants of pain and activity limitations is necessary to improve management of foot OA. The aim of the present study was to investigate demographic, foot-specific and comorbidity-related factors associated with pain and activity limitations in patients with foot OA. Methods: This exploratory cross-sectional study included 75 patients with OA of the foot and/or ankle joints. Demographic and clinical data were collected with questionnaires and by clinical examination. The outcome variables of pain and activity limitations were measured using the Foot Function Index (FFI). Potential determinants were categorized into demographic factors (e.g., age, sex), foot-specific factors (e.g., plantar pressure and gait parameters), and comorbidity-related factors (e.g., type and amount of comorbid diseases). Multivariable regression analyses with backward selection (p-out≥0.05) were performed in two steps, leading to a final model. Results: Of all potential determinants, nine factors were selected in the first step. Five of these factors were retained in the second step (final model): female sex, pain located in the hindfoot, higher body mass index (BMI), neurological comorbidity, and Hospital Anxiety and Depression Scale (HADS) score were positively associated with the FFI score. The explained variance (R 2 ) for the final model was 0.580 (adjusted R 2  â€‹= â€‹0.549). Conclusion: Female sex, pain located in the hindfoot, higher BMI, neurological comorbidity and greater psychological distress were independently associated with a higher level of foot-related pain and activity limitations. By addressing these factors in the management of foot OA, pain and activity limitations may be reduced.

Development of a Patient-Reported Outcomes Measurement Information System (PROMIS®) short form for measuring physical function in geriatric rehabilitation patients.

PURPOSE: To develop and test the validity of a Patient-Reported Outcomes Measurement Information System (PROMIS®) short form for measuring physical function of geriatric rehabilitation patients. METHODS: Experts selected items from the Dutch-Flemish PROMIS v1.2 Physical Function (PROMIS-PF) item bank and proposed new items to develop the PROMIS-PF short form for geriatric rehabilitation (PROMIS-PF-GR). Patients evaluated its content validity. Structural validity was assessed by evaluating unidimensionality (confirmatory, exploratory, and bi-factor analyses [criterion: Omega H > 0.80 and ECV > 0.60]), local independence (criterion: residual correlation < 0.20) ,and monotonicity (criterion: Hi-coefficient ≥ 0.30). Measurement invariance was assessed by evaluating Differential Item Functioning (DIF) between geriatric rehabilitation patients and people from the general population using ordinal logistic regression. Internal consistency was assessed by calculating Cronbach's alpha (criterion: alpha ≥ 0.70). RESULTS: Experts selected 24 items from the PROMIS-PF item bank and proposed one new item which was not included in the short form. Patients considered the 24 items relevant and containing essential information. The PROMIS-PF-GR's psychometric properties were evaluated in 207 patients (mean age ± SD, 80.0 ± 8.3 year; 58% female). The 24 items were found to be sufficiently unidimensional (Omega H = 0.82, ECV = 0.70), locally independent (98.7% item pairs), and monotone (all ≥ 0.32). Five items were flagged for DIF, but their impact on the total score was negligible. Cronbach's alpha was 0.94. CONCLUSION: The PROMIS-PF-GR was developed from the PROMIS-PF and has good content validity, structural validity, measurement invariance, and internal consistency in Dutch geriatric rehabilitation patients. We recommend to confirm the content validity of the PROMIS-PF-GR in other countries.

Higher body mass index is associated with lower foot health in patients with rheumatoid arthritis: baseline results of the Amsterdam-Foot cohort.

Objective: Obesity is highly prevalent in patients with rheumatoid arthritis (RA), with likely impact on weight-bearing foot joints. We explored the associations between body mass index (BMI) and measures of foot health in patients with RA and foot complaints.Method: We examined patients with RA presenting for their first custom-made therapeutic footwear or foot orthoses. Domains of foot health comprised: foot pain, foot-related activity limitations, forefoot plantar pressure, foot synovitis, and foot deformity. In regression analyses, BMI was the independent variable and foot health domains were the dependent variables.Results: The cohort at baseline comprised 230 patients [mean ± sd age 58 ± 13 years, 80% female, mean ± sd disease duration 10 ± 9 years, and median (interquartile range) BMI 26.7 (23.5-30.1) kg/m2]. Small to modest statistically significant associations were found in the majority of the measures studied between a higher BMI and more foot pain, more foot-related activity limitations, higher in-shoe measured forefoot plantar pressure, and the presence of foot synovitis. No relationships were found between BMI and barefoot measured forefoot plantar pressure or foot deformity.Conclusion: BMI is negatively associated with foot health in patients with RA. Although the clinical relevance of our findings for an individual patient is not immediately obvious, future research should consider BMI as a potential therapeutic target to improve foot health.

Graded response model fit, measurement invariance and (comparative) precision of the Dutch-Flemish PROMIS® Upper Extremity V2.0 item bank in patients with upper extremity disorders.

BACKGROUND: The Dutch-Flemish PROMIS® Upper Extremity (DF-PROMIS-UE) V2.0 item bank was recently developed using Item Response Theory (IRT). Unknown for this bank are: (1) if it is legitimate to calculate IRT-based scores for short forms and Computerized Adaptive Tests (CATs), which requires that the items meet the assumptions of and fit the IRT-model (Graded Response Model [GRM]);(2) if it is legitimate to compare (sub) groups of patients using this measure, which requires measurement invariance; and (3) the precision of the estimated patients' scores for patients with different levels of functioning and compared to legacy measures. Aims were to evaluate (1) the assumptions of and fit to the GRM, (2) measurement invariance and (3) (comparative) precision of the DF-PROMIS-UE v2.0. METHODS: Cross-sectional data were collected in Dutch patients with upper extremity disorders. Assessed were IRT-assumptions (unidimensionality [bi-factor analysis], local independence [residual correlations], monotonicity [coefficient H]), GRM item fit, measurement invariance (absence of Differential Item Functioning [DIF] due to age, gender, center, duration, and location of complaints) and precision (standard error of IRT-based scores across levels of functioning). To study measurement invariance for language [Dutch vs. English], additional US data were used. Legacy instruments were the Disability of the Arm, Shoulder and Hand (DASH), the QuickDASH and the Michigan Hand Questionnaire (MHQ). RESULTS: In total 521 Dutch (mean age ± SD = 51 ± 17 years, 49% female) and 246 US patients (mean age ± SD = 48 ± 14 years, 69% female) participated. The DF-PROMIS-UE v2.0 item bank was sufficiently unidimensional (Omega-H = 0.80, Explained Common Variance = 0.68), had negligible local dependence (four out of 1035 correlations > 0.20), good monotonicity (H = 0.63), good GRM fit (no misfitting items) and demonstrated sufficient measurement invariance. Precise estimates (Standard Error < 3.2) were obtained for most patients (7-item short form, 88.5%; standard CAT, 91.3%; and, fixed 7-item CAT, 87.6%). The DASH displayed better reliability than the DF-PROMIS-UE short form and standard CAT, the QuickDASH displayed comparable reliability. The MHQ-ADL displayed better reliability than the DF-PROMIS-UE short form and standard CAT for T-scores between 28 and 50. For patients with low function, the DF-PROMIS-UE measures performed better. CONCLUSIONS: The DF-PROMIS-UE v2.0 item bank showed sufficient psychometric properties in Dutch patients with UE disorders.

Course and predictors of upper leg muscle strength over 48 months in subjects with knee osteoarthritis: Data from the osteoarthritis initiative.

Objectives: Weakness of upper leg muscles has a negative impact on future disease and functional status in subjects with knee osteoarthritis (OA). The aims of the present study were to (i) describe the course of muscle strength over 48 months and (ii) identify baseline predictors for a decline in upper leg muscle strength over time in subjects with knee OA. Methods: Data were obtained from the Osteoarthritis Initiative (OAI) database, a multicenter, observational study of knee OA. Upper leg muscle strength (in N/kg) was measured at baseline, 24 and 48 months. Potential baseline predictors included demographics, OA-specific and health and lifestyle related factors. Linear mixed model analyses were performed. Results: A total of 1390 subjects with knee osteoarthritis were included. A statistically significant decline of muscle strength was found between baseline and 24 months (B = -0.186, 95%CI [-0.358,-0.014], p = 0.03), but not between other time points (24-48 months p = 0.89, and baseline and 48 months p = 0.058). Predictors of a decline in muscle strength over time included demographic predictors (older age, being female, higher body mass index (BMI)), one lifestyle predictor (lower dietary protein intake) and one OA-specific predictor (radiographic severity). Conclusions: Muscle strength declined over time in subjects with knee OA. The identified predictors may help clinicians to select and treat subjects with knee OA at risk of a decline in muscle strength.

Evaluation of treatment outcome using the Patient Specific Functional Scale in knee osteoarthritis patients undergoing multidisciplinary rehabilitation.

Objective: First, to make an inventory of activity limitations commonly reported by knee osteoarthritis (OA) patients undergoing multidisciplinary rehabilitation. Second, to evaluate treatment outcome using the Patient Specific Functional Scale (PSFS) and compare it to the Western Ontario and McMasters Universities Osteoarthritis Index physical function subscale (WOMAC-pf). Design: An observational study with assessments before and immediately after multidisciplinary rehabilitation. Five hundred and thirteen patients used the PSFS, a patient-reported tool to identify activity limitations and score the patient's ability to perform the activity on an 11-point Numeric Rating Scale (NRS), to report three activities in which they were limited. Frequencies and percentages of their highest-prioritized activity were calculated and categorized according to the International Classification of Functioning, Disability, and Health (ICF). Paired-samples T-tests were used to analyze the change in ability to perform the activities. Effect sizes of PSFS and WOMAC-pf were compared. Results: Most patients indicated limitations in walking, walking up/down stairs, prolonged standing, and standing up from a chair. Following these common activities, 26 different activities were identified. The majority of these highest-prioritized activities fell under the first-level ICF category of Mobility. The ability to perform all activities significantly improved after treatment. Effect sizes ranged between 0.60 and 0.97 and were greater than the effect size of the WOMAC-pf (0.41). Conclusion: Knee OA patients who undergo multidisciplinary rehabilitation exhibit improvements in performing daily activities. The PSFS is a valuable tool to evaluate patient-specific activity limitations and seems to capture improvements in activity limitations beyond the WOMAC-pf.

Is a model of stratified exercise therapy by physical therapists in primary care feasible in patients with knee osteoarthritis? : a mixed methods study.

OBJECTIVES: To explore the feasibility of a newly developed model of stratified exercise therapy in primary care for patients with knee osteoarthritis (OA). DESIGN: Mixed method design (process, outcome and qualitative evaluation). SETTING: Six physical therapy practices in primary care around Amsterdam. PARTICIPANTS: Fifty eligible patients with knee OA, visiting one of the participating physical therapists (PTs). INTERVENTION: Patients were allocated to a subgroup based on a simple stratification tool and received subgroup-specific, protocolized, 4-month, exercise therapy. MAIN OUTCOME MEASURES: Feasibility of this model of stratified exercise therapy was explored by multiple process parameters, outcome measures (physical functioning and knee pain; at baseline and 4-months follow-up) and experiences from patients and PTs. RESULTS: From 97 potentially eligible patients, fifty patients were included and allocated to the 'high muscle strength subgroup' (n=17), 'depression subgroup' (n=4), 'obesity subgroup' (n=6) or 'low muscle strength subgroup' (n=23). Three patients dropped out during the study period. PTs provided relatively low numbers of sessions (on average 10 sessions), although exceedance of the recommended maximum number of sessions did occur frequently. We found clinically relevant improvements on physical functioning and knee pain (P<0.001 for both) for the total group. In general, the model of stratified exercise therapy was considered to be easily applicable and of added value for daily practice. CONCLUSIONS: Our model of stratified exercise therapy seems to be feasible in primary care, although a number of limitations were reported. Future research should determine the (cost-)effectiveness of an adapted model, compared to usual, non-stratified exercise therapy.

Dietary protein intake and upper leg muscle strength in subjects with knee osteoarthritis: data from the osteoarthritis initiative.

The aims of this study were (1) to describe dietary protein intake, and (2) to evaluate the association between dietary protein intake and upper leg muscle strength in subjects with knee osteoarthritis (OA). Baseline data from the OA was used, in a cross-sectional study. All subjects were diagnosed with symptomatic and radiographic knee OA. Daily dietary protein intake was measured with the Block Brief 2000 food frequency questionnaire (g/kg body weight). The sum of knee flexion and extension strength of the index knee (N/kg bodyweight) was assessed with the Good Strength chair test. Linear regression analysis was used to test the association between dietary protein intake and muscle strength, adjusting for relevant confounders. Data from 1316 subjects (mean age 61.4 ± SD 9.1 years, 57.0% female) were used. The mean daily protein intake was 0.72 ± SD 0.30 g/kg bodyweight, and 65.1% of the subjects had a protein intake lower than the recommended daily allowance of 0.8 g/kg bodyweight. The mean muscle strength was 5.4 ± SD 2.1 N/kg bodyweight. Lower protein intake was significantly associated with lower muscle strength (B = 0.583, 95% CI 0.230-0.936, p = 0.001). The majority of the subjects with knee OA had a dietary protein intake lower than the recommended daily allowance. Lower protein intake was associated with lower upper leg muscle strength. Longitudinal observational and interventional studies are needed to establish whether dietary protein intake has a causal effect on muscle strength in subjects with knee OA.

Validation of two PROMIS item banks for measuring social participation in the Dutch general population.

BACKGROUND: The Patient-Reported Outcomes Measurement Information System (PROMIS) item banks 'Ability to Participate in Social Roles and Activities' (35 items) and 'Satisfaction with Social Roles and Activities' (44 items) were developed to measure (satisfaction with) participation more efficiently and precisely than current instruments, by using Computerized Adaptive Testing (CAT). We validated these item banks in a Dutch general population. METHODS: Participants in an internet panel completed both item banks. Unidimensionality, local dependence, monotonicity, Graded Response Model item fit, Differential Item Functioning (DIF) for age, gender, education, region, ethnicity, and language (Dutch compared to US Social Supplement), and reliability were assessed. RESULTS: A representative Dutch sample of 1002 people participated. We found for the Ability to Participate and Satisfaction with Participation item banks, respectively, sufficient unidimensionality (CFI: 0.971, 0.960; TLI: 0.970, 0.958; RMSEA: 0.108, 0.108), no local dependence, sufficient monotonicity (H: 0.75, 0.73), good item fit (2 out of 35 items, 1 out of 44 items with S-X2p-value < 0.001). No DIF was found. We found a reliability of at least 0.90 with simulated CATs in 86% and 94% of the participants with on average 4.7 (range 2-12) and 4.3 (range 3-12) items, respectively. DISCUSSION: The PROMIS participation item banks showed sufficient psychometric properties in a general Dutch population and can be used as CAT. PROMIS CATs allow reliable and valid measurement of participation in an efficient and user-friendly way with limited administration time.

Forefoot pathology in relation to plantar pressure distribution in patients with rheumatoid arthritis: A cross-sectional study in the Amsterdam Foot cohort.

BACKGROUND: In patients with rheumatoid arthritis (RA), both high and low forefoot plantar pressures have been reported. Better understanding of pathology in the forefoot associated with altered pressure distribution in patients with RA could help to better formulate and specify goals for treatment with foot orthoses or therapeutic footwear. OBJECTIVES: To investigate the association of plantar pressure with disease activity and deformity in the forefoot in patients with rheumatoid arthritis and forefoot symptoms. METHODS: A cross sectional study, using data of 172 patients with rheumatoid arthritis and forefoot symptoms, was conducted. Peak pressure (PP) and pressure time integral (PTI) in the forefoot were measured with a pressure platform. Forefoot deformity was assessed using the Platto score. Forefoot disease activity was defined as swelling and/or pain assessed by palpation of the metatarsophalangeal joints. The forefoot was divided in a medial, central and lateral region, in which the following conditions could be present: 1) no pathology, 2) disease activity, 3) deformity or 4) disease activity and deformity. A multilevel analysis was performed using condition per forefoot region as independent variable and PP or PTI in the corresponding region as dependent variable. RESULTS: Statistically significant higher plantar pressures were found in forefoot regions with deformities (RR 1.2, CI 1.1-1.3, P<0.0001), compared to forefoot regions without forefoot pathology. No significant differences in plantar pressures were found when solely forefoot disease activity was present in forefoot regions. SIGNIFICANCE: Forefoot deformities are related to higher plantar pressures measured in the corresponding forefoot regions. The absence of an association between local disease activity and plantar pressure might be explained by the low prevalence of metatarsophalangeal joint pain or swelling. Future research with sensitive imaging measures to detect disease activity is recommended to reveal the effect of forefoot disease activity on plantar pressure.

Mortality in patients with rheumatoid arthritis: a 15-year prospective cohort study.

The aim of this study was to investigate (a) the mortality in a clinical cohort of patients with established rheumatoid arthritis in comparison with the general Dutch population over 15 years, (b) the trend in the mortality ratio during the study period, and (c) causes of death and compare these with the general population. In 1997, a sample of 1222 patients was randomly selected from the register of a large rheumatology outpatient clinic. Their mortality and primary causes of death between 1997 and 2012 were obtained from Statistics Netherlands. The standardized mortality ratio (SMR) for all-cause mortality and the number of life-years lost in the study period, adjusted for age, sex, and calendar year, were calculated. A linear poisson regression analysis was performed to evaluate change in all-cause SMR over time. Finally, the SMRs for cause-specific mortality were calculated. The mean age of the population at baseline was 60.4 (SD 15.4) years, and 72.6% of the patients were women. The estimated SMR (95% CI) for all-cause mortality was 1.54 (1.41, 1.67) with about one life-year lost over the study period. There was a trend to decreasing SMR (2% annually, p = .07). Mortality was higher compared with the general population for circulatory system diseases, respiratory system diseases, musculoskeletal system diseases, and digestive system diseases (p < .05). The observed mortality among patients with RA was 54% higher than in the general population after adjustment for age, sex and calendar year. More than one life-year was lost over 15 years, and the mortality tended to decrease over time. The mortality was higher for cardiovascular, respiratory, musculoskeletal and digestive diseases.

Association of Somatic Comorbidities and Comorbid Depression With Mortality in Patients With Rheumatoid Arthritis: A 14-Year Prospective Cohort Study.

OBJECTIVE: Patients with rheumatoid arthritis (RA) have a significantly increased risk of mortality compared with the general population. One of the most important predictors for mortality is somatic comorbidity. Moreover, studies have demonstrated that comorbid depression is associated with mortality. Which specific comorbidities are associated with mortality is less investigated. The purpose of this study was to investigate the association of a wide range of comorbidities with mortality in patients with RA. METHODS: Longitudinal data over a 14-year period were collected from 882 patients with RA. Data were assessed with questionnaires. The mortality status was obtained from the Statistics Netherlands for the period 1996-2011 for 99% of the patients. Somatic comorbidity was assessed in 1997, 1998, 1999, and 2008 and measured by a national population-based questionnaire including 20 chronic diseases. Comorbid depression was assessed in 1997, 1998, and 1999 and measured with the Center for Epidemiologic Studies Depression Scale. Cox regression was used to study the relationship between comorbidity and mortality. RESULTS: At baseline, 72% of the patients were women. The mean ± SD age was 59.3 ± 14.8 years, and the median (interquartile range) disease duration was 5.0 (2.0-14.0) years. A total of 345 patients died during the study period. Comorbidities that were associated with mortality were circulatory conditions (hazard ratio [HR] 1.60 [95% confidence interval (95% CI) 1.15-2.22]), respiratory conditions (HR 1.43 [95% CI 1.09-1.89]), cancer (HR 2.00 [95% CI 1.28-3.12]), and depression (HR 1.35 [95% CI 1.06-1.72]). CONCLUSION: Comorbid circulatory conditions, respiratory conditions, cancer, and depression are associated with mortality among patients with RA. Careful monitoring of these comorbidities during the course of the disease and adequate referral may improve health outcomes and chances of surviving.

Calibration of the Dutch-Flemish PROMIS Pain Behavior item bank in patients with chronic pain.

BACKGROUND: The aims of the current study were to calibrate the item parameters of the Dutch-Flemish PROMIS Pain Behavior item bank using a sample of Dutch patients with chronic pain and to evaluate cross-cultural validity between the Dutch-Flemish and the US PROMIS Pain Behavior item banks. Furthermore, reliability and construct validity of the Dutch-Flemish PROMIS Pain Behavior item bank were evaluated. METHODS: The 39 items in the bank were completed by 1042 Dutch patients with chronic pain. To evaluate unidimensionality, a one-factor confirmatory factor analysis (CFA) was performed. A graded response model (GRM) was used to calibrate the items. To evaluate cross-cultural validity, Differential item functioning (DIF) for language (Dutch vs. English) was evaluated. Reliability of the item bank was also examined and construct validity was studied using several legacy instruments, e.g. the Roland Morris Disability Questionnaire. RESULTS: CFA supported the unidimensionality of the Dutch-Flemish PROMIS Pain Behavior item bank (CFI = 0.960, TLI = 0.958), the data also fit the GRM, and demonstrated good coverage across the pain behavior construct (threshold parameters range: -3.42 to 3.54). Analysis showed good cross-cultural validity (only six DIF items), reliability (Cronbach's α = 0.95) and construct validity (all correlations ≥0.53). CONCLUSIONS: The Dutch-Flemish PROMIS Pain Behavior item bank was found to have good cross-cultural validity, reliability and construct validity. The development of the Dutch-Flemish PROMIS Pain Behavior item bank will serve as the basis for Dutch-Flemish PROMIS short forms and computer adaptive testing (CAT).

The ability of systemic biochemical markers to reflect presence, incidence, and progression of early-stage radiographic knee and hip osteoarthritis: data from CHECK.

OBJECTIVE: To relate systemic biochemical markers of joint metabolism to presence, incidence, and progression of early-stage radiographic knee and/or hip osteoarthritis (OA). METHOD: The cartilage markers uCTX-II, sCOMP, sPIIANP, and sCS846, bone markers uCTX-I, uNTX-I, sPINP, and sOC, and synovial markers sHA and sPIIINP were assessed by enzyme-linked immunosorbent assay or radioactive immunoassay in baseline samples of CHECK (Cohort Hip and Cohort Knee), a cohort study of early-stage symptomatic knee and/or hip OA. Knee and hip radiographs were obtained at baseline and 5-year follow-up. Presence of OA at baseline was defined as Kellgren and Lawrence (K&L) = 1 (maximum observed). Incidence of OA was defined as K&L = 0 at baseline and K&L ≥ 1 at 5-year follow-up. Progression of OA was defined as K&L = 1 at baseline and K&L ≥ 2 at 5-year follow-up. RESULTS: Data were available for 801 subjects at baseline and for 723 subjects at both baseline and 5-year follow-up. Multiple cartilage and synovial markers showed positive associations with presence and progression of knee and hip OA and with incidence of hip OA, except for negative associations of uCTX-II and sCOMP with incidence of knee OA. uCTX-II and sCOMP showed multiple interactions with other biomarkers in their associations with knee and hip OA. Bone markers were positively associated with presence of radiographic knee OA, but negatively associated with progression of radiographic hip OA. CONCLUSION: Especially metabolism in cartilage and synovial matrix appear to be of relevance in knee and hip OA. The role of bone metabolism appears to differ between knee and hip OA.

Clinical phenotypes in patients with knee osteoarthritis: a study in the Amsterdam osteoarthritis cohort.

OBJECTIVE: To identify and validate previously established phenotypes of knee osteoarthritis (OA) based on similarities in clinical patient characteristics. METHODS: Knee OA patients (N = 551) from the Amsterdam OA (AMS-OA) cohort provided data. Four clinical patient characteristics were assessed: upper leg muscle strength, body mass index (BMI), radiographic severity (Kellgren/Lawrence [KL] grade), and depressive mood (the Hospital Anxiety and Depression Scale [HADS] questionnaire). Cluster analysis was performed to identify the optimal number of phenotypes. Differences in clinical characteristics between the phenotypes were analyzed with ANOVA. RESULTS: Cluster analysis identified five phenotypes of knee OA patients: "minimal joint disease phenotype", "strong muscle strength phenotype", "severe radiographic OA phenotype", "obese phenotype", and "depressive mood phenotype". CONCLUSIONS: Among patients with knee OA, five phenotypes were identified based on four clinical characteristics. To a high degree, the results are a replication of earlier findings in the OA Initiative, indicating that these five phenotypes seem a stable, valid, and clinically relevant finding.

Improvement in upper leg muscle strength underlies beneficial effects of exercise therapy in knee osteoarthritis: secondary analysis from a randomised controlled trial.

OBJECTIVES: Although exercise therapy is effective for reducing pain and activity limitations in patients with knee osteoarthritis (OA), the underlying mechanisms are unclear. This study aimed to evaluate if improvements in neuromuscular factors (i.e. upper leg muscle strength and knee proprioception) underlie the beneficial effects of exercise therapy in patients with knee OA. DESIGN: Secondary analyses from a randomised controlled trial, with measurements at baseline, 6 weeks, 12 weeks and 38 weeks. SETTING: Rehabilitation centre. PARTICIPANTS: One hundred and fifty-nine patients diagnosed with knee OA. INTERVENTION: Exercise therapy. MAIN OUTCOME MEASURES: Changes in pain [numeric rating scale (NRS)] and activity limitations [Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) physical function subscale and get-up-and-go test] during the study period. Independent variables were changes in upper leg muscle strength and knee joint proprioception (i.e. motion sense) during the study period. Longitudinal regression analyses (generalised estimating equation) were performed to analyse associations between changes in upper leg muscle strength and knee proprioception with changes in pain and activity limitations. RESULTS: Improved muscle strength was significantly associated with reductions in NRS pain {B coefficient -2.5 [95% confidence interval (CI) -3.7 to -1.4], meaning that every change of 1 unit of strength was linked to a change of -2.5 units of pain}, WOMAC physical function (-8.8, 95% CI -13.4 to -4.2) and get-up-and-go test (-1.7, 95% CI -2.4 to -1.0). Improved proprioception was not significantly associated with better outcomes of exercise therapy (P>0.05). CONCLUSIONS: Upper leg muscle strengthening is one of the mechanisms underlying the beneficial effects of exercise therapy in patients with knee OA.

Development and preliminary testing of a computerized animated activity questionnaire in patients with hip and knee osteoarthritis.

OBJECTIVE: To develop an Animated Activity Questionnaire (AAQ) based on video animations for assessing activity limitations in patients with hip/knee osteoarthritis (OA) that combines the advantages of self-reported questionnaires and performance-based tests without many of their limitations and to preliminarily assess its reliability and validity. We hypothesized that the AAQ would correlate highly with performance-based tests and moderately with self-reported questionnaires. METHODS: Item selection was based on the pilot AAQ, prespecified conditions, the International Classification of Functioning, Disability, and Health core set for OA, existing measurement instruments, and focus groups of patients. Test-retest reliability was assessed in 30 of 110 patients. In 110 patients, correlations were calculated between the AAQ and the self-reported Hip Disability/Knee Injury and Osteoarthritis Outcome Score activities of daily living subscale (H/KOOS). In 45 of 110 patients, correlations with performance-based tests (stair climbing test, timed up and go test, and 30-second chair stand test) were calculated. RESULTS: In total, 17 basic daily activities were chosen for the AAQ. Video animations were made showing a person performing each activity with 3-5 different levels of difficulty. Patients were asked to select the level that best matched their own performance. Reliability was high (intraclass correlation coefficient 0.97 [95% confidence interval 0.93-0.98]); the AAQ correlated highly with performance-based tests (0.62), but higher with the H/KOOS (0.76) than expected. CONCLUSION: A computerized AAQ for assessing activity limitations was developed. Content validity was considered good. Preliminary validation results showed high reliability, but construct validity needs further study with a larger sample size. Continuing research will focus on construct validity and crosscultural validity.