Construction and psychometric properties of the Belgian Rheumatoid Arthritis Disability Assessment (BRADA) questionnaire: a new tool for the evaluation of activity limitations in patients with rheumatoid arthritis

To describe the construction and psychometric properties of the Belgian Rheumatoid Arthritis Disability Assessment (BRADA) questionnaire, a self-report tool to evaluate chronic activity limitations in patients with rheumatoid arthritis (RA). The BRADA was developed to assess the eligibility of patients with RA for financial and social support measures. The BRADA questionnaire evaluates functioning in 6 functional domains (mobility, nutrition, self care, household tasks, awareness of danger and communication) over the past week and the past 3 months. To assess the psychometric properties of the BRADA, patients with moderate to severe RA filled out the BRADA, HAQ-DI and SF-36 questionnaires twice, with a four-week interval. At each visit, the total number of swollen and tender joints, and global disease activity were recorded. DAS 28 was measured at the first visit. Internal consistency of items per domain was evaluated with Cronbach's alpha method. Intraclass correlation coefficient (ICC) analysis was used to assess test-retest reliability. BRADA scores were compared to HAQ, SF-36 scores and disease activity parameters with Spearman's Rho correlation coefficients to assess construct validity. Experts considered the content and face validity of BRADA to be adequate. Internal consistency was satisfactory for all functional domains (alpha >0.75), as was the test-retest reliability (ICC 0.78). BRADA scores showed excellent correlation with other validated questionnaires in RA (HAQ-DI, SF-36) and with measures of disease activity (VAS, DAS28)(p