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 (Cronbach’s 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 gou

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 population

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

INTRODUCTION: Patient-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. METHODS: The 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. RESULTS: Few 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. CONCLUSIONS: Results 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

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

Crosscultural measurement equivalence of the Health Assessment Questionnaire II

OBJECTIVE: To evaluate the cross-cultural measurement equivalence of the US and Dutch Health Assessment Questionnaire II (HAQ-II) in rheumatoid arthritis (RA). METHODS: Item response theory (IRT) analyses were performed on US (n=18747) and Dutch (n=1022) HAQ-II data to evaluate the equivalence of cross-cultural item performance. Observed inconsistencies were modeled by assigning country-specific item parameters to biased items. The impact of cross-cultural item bias on the comparability of the Dutch and US total scores was analyzed by evaluating the agreement between physical function levels estimated from an IRT model with country specific-item parameters for biased items and the physical function levels estimated from the original model that does not account for cultural bias. RESULTS: Two items showed significant cross-cultural bias. However, the agreement in physical function estimates between the respecified and original model was very high with ICC >0.99 and the Bland–Altman limits of agreement ranging from -0.08 to 0.07 on a latent scale with a mean of 0 and standard deviation 1. CONCLUSIONS: This study suggests that the Dutch and US HAQ-II produce total scores that can be interpreted interchangeably across countries in RA studies, despite some minor bias at the item level

Linking Physical Function Outcomes in Rheumatology: Performance of a Crosswalk for Converting Health Assessment Questionnaire Scores to Short Form 36 Physical Functioning Scale Scores

Objective To evaluate the reliability of a crosswalk, developed in The Netherlands, between the Health Assessment Questionnaire (HAQ) disability index (DI) and the Short Form 36 physical functioning scale (PF-10) in a sample of patients with various rheumatic diseases in the US. Methods Baseline data from patients with rheumatoid arthritis (RA; n = 29,020), fibromyalgia (FM; n = 3,776), and systemic lupus erythematosus (SLE; n = 1,609) participating in the National Data Bank for Rheumatic Diseases were analyzed. Reliability of the crosswalk was evaluated by calculating intraclass correlation coefficients (ICCs), and agreement between observed and predicted scores was evaluated using the Bland-Altman approach. Results The crosswalk produced reliable conversions for both the HAQ DI (ICC range 0.70–0.77) and PF-10 (ICC range 0.73–0.78) in all 3 disease groups. The mean difference between observed and expected scores was close to zero in US patients with RA. For all 3 disease groups, the limits of agreement were fairly wide and conversion at the level of individual patients is not recommended. Conclusion The crosswalk produced reliable conversions at the group level in a crosscultural setting and can be used to convert HAQ DI to PF-10 scores and vice versa in US patients with RA, FM, or SL