Martijn A. H. Oude Voshaar

Further evaluation of the psychometric properties of the Acceptance and Action Questionnaire-II

The Acceptance and Action Questionnaire-II (AAQ-II) is a self-report measure designed to assess experiential avoidance as conceptualized in acceptance and commitment therapy (ACT). The current study is the first to evaluate the psychometric properties of the AAQ-II in a large sample of adults (N = 376) with mild to moderate levels of depression and anxiety who participated in a study on the effects of an ACT intervention. The internal construct validity and local measurement precision were investigated by fitting the data to a unidimensional item response theory (IRT) model, and the incremental validity of the AAQ-II beyond mindfulness, as measured by the Five Facet Mindfulness Questionnaire, was assessed. Results of the IRT analyses suggest that the AAQ-II is a unidimensional measure of experiential avoidance and has satisfactory reliability for group comparisons in mild to moderately depressed and anxious populations. Item functioning was found to be independent of gender and slightly dependent on age in this sample. Furthermore, the AAQ-II showed incremental validity beyond 5 mindfulness facets in explaining depression, anxiety, and positive mental health. This study suggests the AAQ-II shows promise as a useful tool for the measurement of experiential avoidance in mild to moderately depressed and anxious populations.

Measurement properties of physical function scales validated for use in patients with rheumatoid arthritis: A systematic review of the literature

BackgroundThe aim of this study was to systematically review the content validity and measurement properties of all physical function (PF) scales which are currently validated for use with patients with rheumatoid arthritis (RA).MethodsSystematic literature searches were performed in the Scopus and PubMed databases to identify articles on the development or psychometric evaluation of PF scales for patients with RA. The content validity of included scales was evaluated by linking their items to the International Classification of Functioning Disability and Health (ICF). Furthermore, available evidence of the reliability, validity, responsiveness, and interpretability of the included scales was rated according to published quality criteria.ResultsThe search identified 26 questionnaires with PF scales. Ten questionnaires were rated to have adequate content validity. Construct validity, internal consistency, test-retest reliability and responsiveness was rated favourably for respectively 15, 11, 5, and 6 of the investigated scales. Information about the absolute measurement error and minimal important change scores were rarely reported.ConclusionBased on this literature review, the disease-specificHAQ and the generic SF-36 can currently be most confidently recommended to measure PF in RA for most research purposes. The HAQ, however, was frequently associated with considerable ceiling effects while the SF-36 has limited content coverage. Alternative scales that might be better suited for specific research purposes are identified along with future directions for research.

Comparison of measures of functional disability in patients with gout

OBJECTIVE To compare the measurement properties of the HAQ disability index (HAQ-DI), HAQ-II and short form 36 physical functioning scale (PF-10) in patients with gout. METHODS A cross-sectional sample of 97 patients with gout completed all three measures. Reliability was assessed by examining the internal consistency of the scales. Validity was assessed by testing for expected intercorrelations and associations with other aspects of health status and the ability to discriminate between patients with different levels of general health. Additionally, distributional properties were examined. RESULTS All three measures demonstrated high reliability (Cronbachs α ≥ 0.93), strong intercorrelations (r  ≥  0.75), and the expected pattern of external correlations. The HAQ-DI and HAQ-II performed somewhat better in discriminating between patients. However, both demonstrated ceiling effects of 34.0 and 25.8%, respectively, compared with only 7.2% of the patients scoring no disability on the PF-10. CONCLUSIONS The HAQ-DI, HAQ-II and PF-10 demonstrated similar and adequate reliability and validity for measuring functional disability in patients with gout. The large ceiling effects of both HAQ versions, however, may point to limited content validity and responsiveness to change. Further research should examine whether current instruments cover all aspects of physical functioning relevant to patients with gout.

Calibration of the PROMIS Physical Function Item Bank in Dutch Patients with Rheumatoid Arthritis

Objective To calibrate the Dutch-Flemish version of the PROMIS physical function (PF) item bank in patients with rheumatoid arthritis (RA) and to evaluate cross-cultural measurement equivalence with US general population and RA data. Methods Data were collected from RA patients enrolled in the Dutch DREAM registry. An incomplete longitudinal anchored design was used where patients completed all 121 items of the item bank over the course of three waves of data collection. Item responses were fit to a generalized partial credit model adapted for longitudinal data and the item parameters were examined for differential item functioning (DIF) across country, age, and sex. Results In total, 690 patients participated in the study at time point 1 (T2, N = 489; T3, N = 311). The item bank could be successfully fitted to a generalized partial credit model, with the number of misfitting items falling within acceptable limits. Seven items demonstrated DIF for sex, while 5 items showed DIF for age in the Dutch RA sample. Twenty-five (20%) items were flagged for cross-cultural DIF compared to the US general population. However, the impact of observed DIF on total physical function estimates was negligible. Discussion The results of this study showed that the PROMIS PF item bank adequately fit a unidimensional IRT model which provides support for applications that require invariant estimates of physical function, such as computer adaptive testing and targeted short forms. More studies are needed to further investigate the cross-cultural applicability of the US-based PROMIS calibration and standardized metric.

Development and evaluation of a crosswalk between the SF-36 physical functioning scale and Health Assessment Questionnaire disability index in rheumatoid arthritis

BackgroundThe SF-36 physical functioning scale (PF-10) and the Health Assessment Questionnaire disability index (HAQ-DI) are the most frequently used instruments for measuring self-reported physical function in rheumatoid arthritis (RA). The objective of this study was to develop a crosswalk between scores on the PF-10 and HAQ-DI in RA.MethodsItem response theory (IRT) methods were used to co-calibrate both scales using data from 1791 RA patients. The appropriateness of a Rasch-based crosswalk was evaluated by comparing it with crosswalks based on a two-parameter and a multi-dimensional IRT model. The accuracy of the final crosswalk was cross-validated using baseline (n = 532) and 6-month follow-up (n = 276) data from an independent cohort of early RA patients.ResultsThe PF-10 and HAQ-DI adequately fit a unidimensional Rasch model. Both scales measured a wide range of functioning, although the HAQ-DI tended to better target lower levels of functioning. The Rasch-based crosswalk performed similarly to crosswalks based on the two-parameter and multidimensional IRT models. Agreement between predicted and observed scale scores in the cross-validation sample was acceptable for group-level comparisons. The longitudinal validity in discriminating between disease response states was similar between observed and predicted scores.ConclusionThe crosswalk developed in this study allows for converting scores from one scale to the other and can be used for group-level analyses in patients with RA.

Validity and measurement precision of the PROMIS physical function item bank and a content validity-driven 20-item short form in rheumatoid arthritis compared with traditional measures

OBJECTIVE To evaluate the content validity and measurement properties of the Patient-Reported Outcome Measurement Information System (PROMIS) physical function item bank and a 20-item short form in patients with RA in comparison with the HAQ disability index (HAQ-DI) and 36-item Short Form Health Survey (SF-36) physical functioning scale (PF-10). METHODS The content validity of the instruments was evaluated by linking their items to the International Classification of Functioning, Disability and Health (ICF) core set for RA. The measures were administered to 690 RA patients enrolled in the Dutch Rheumatoid Arthritis Monitoring registry. Measurement precision was evaluated using item response theory methods and construct validity was evaluated by correlating physical function scores with other clinical and patient-reported outcome measures. RESULTS All 207 health concepts identified in the physical function measures referred to activities that are featured in the ICF. Twenty-three of 26 ICF RA core set domains are featured in the full PROMIS physical function item bank compared with 13 and 8 for the HAQ-DI and PF-10, respectively. As hypothesized, all three physical function instruments were highly intercorrelated (r 0.74-0.84), moderately correlated with disease activity measures (r 0.44-0.63) and weakly correlated with age (rs 0.07-0.14). Item response theory-based analysis revealed that a 20-item PROMIS physical function short form covered a wider range of physical function levels than the HAQ-DI or PF-10. CONCLUSION The PROMIS physical function item bank demonstrated excellent measurement properties in RA. A content-driven 20-item short form may be a useful tool for assessing physical function in RA.

Experiences of gout-related disability from the patients’ perspective: a mixed methods study

Disability is a common problem in patients with gout. Recently, the Health Assessment Questionnaire Disability Index (HAQ-DI) was recommended for assessing patient-reported activity limitations in gout. However, few studies have explored experiences and issues of disability from the perspective of gout patients themselves. The objectives of this study were to explore disability issues in patients with gout and to examine the content validity of the HAQ-DI in this patient group. Two studies were performed: a semi-structured interview study with seven male gout patients and a cross-sectional survey study among 34 other patients with gout. In both studies, specific examples of activity limitations were elicited using open-ended methods. The survey study additionally aimed to quantify the relevance of the activities listed in the HAQ-DI. Most patients experienced several gout attacks in the previous year. Limitations were reported to occur during a flare, but patients were generally not limited between attacks. During an attack, patients mainly experienced limitations related to mobility, especially walking and climbing stairs. Patients also mentioned limitations in activities related to domestic life, such as gardening and doing housework. Limitations related to self-care or activities requiring the use of the upper extremities were rarely mentioned. Corresponding HAQ-DI items were skewed towards very low disability scores over the past week. Assessments of gout-related disability should particularly focus on mobility and lower extremity functioning and should consider the intermittent nature of the disease. The HAQ-DI may not adequately meet these requirements, suggesting the need to explore other measures of gout-related disability.

Relative Performance of Commonly Used Physical Function Questionnaires in Rheumatoid Arthritis and a Patient‐Reported Outcomes Measurement Information System Computerized Adaptive Test

To evaluate and compare the measurement precision and sensitivity to change of the Health Assessment Questionnaire disability index (HAQ DI), the Short Form 36 physical functioning scale (PF‐10), and simulated Patient‐Reported Outcomes Measurement Information System (PROMIS) physical function computer adaptive tests (CATs) with 5, 10, and 15 items, using item response theory–based simulation studies.

Predictors of satisfactory improvements in pain for patients with early rheumatoid arthritis in a treat-to-target study

OBJECTIVE The aim of this study was to identify baseline predictors of achieving patient-perceived satisfactory improvement (PPSI) in pain after 6 months of treat to target in patients with early RA. METHODS Baseline and 6 month data were used from patients included in the Dutch Rheumatoid Arthritis Monitoring remission induction cohort study. Simple and multivariable logistic regression analyses were used to identify significant predictors of achieving an absolute improvement of 30 mm or a relative improvement of 50% on a visual analogue scale for pain. RESULTS At 6 months, 125 of 209 patients (59.8%) achieved an absolute PPSI and 130 patients (62.2%) achieved a relative PPSI in pain. Controlling for baseline pain, having symmetrical arthritis was the strongest independent predictor of achieving an absolute [odds ratio (OR) 3.17, P = 0.03] or relative (OR 3.44, P = 0.01) PPSI. Additionally, anti-CCP positivity (OR 2.04, P = 0.04) and having ≤12 tender joints (OR 0.29, P = 0.01) were predictive of achieving a relative PPSI. The total explained variance of baseline predictors was 30% for absolute and 18% for relative improvements, respectively. CONCLUSION Symmetrical joint involvement, anti-CCP positivity and fewer tender joints at baseline are prognostic signs for achieving satisfactory improvement in pain after 6 months of treat to target in patients with early RA.

Dutch translation and cross-cultural adaptation of the PROMIS® physical function item bank and cognitive pre-test in Dutch arthritis patients

IntroductionPatient-reported physical function is an established outcome domain in clinical studies in rheumatology. To overcome the limitations of the current generation of questionnaires, the Patient-Reported Outcomes Measurement Information System (PROMIS®) project in the USA has developed calibrated item banks for measuring several domains of health status in people with a wide range of chronic diseases. The aim of this study was to translate and cross-culturally adapt the PROMIS physical function item bank to the Dutch language and to pretest it in a sample of patients with arthritis.MethodsThe items of the PROMIS physical function item bank were translated using rigorous forward-backward protocols and the translated version was subsequently cognitively pretested in a sample of Dutch patients with rheumatoid arthritis.ResultsFew issues were encountered in the forward-backward translation. Only 5 of the 124 items to be translated had to be rewritten because of culturally inappropriate content. Subsequent pretesting showed that overall, questions of the Dutch version were understood as they were intended, while only one item required rewriting.ConclusionsResults suggest that the translated version of the PROMIS physical function item bank is semantically and conceptually equivalent to the original. Future work will be directed at creating a Dutch-Flemish final version of the item bank to be used in research with Dutch speaking populations.