A primary therapeutic goal in rheumatoid arthritis (RA) is to reduce functional disability. The recent introduction of several new drugs for RA creates a need for readily assessing the effectiveness of therapy. Because the consistent use of disease-modifying anti-rheumatic drugs (DMARDs) reduces long-term disability, we analysed the large database of 1817 RA patients from leflunomide trials to assess if changes in the Health Assessment Questionnaire (HAQ) can measure the effectiveness of RA therapy.
Data from three randomized double-blind RA trials were evaluated. The patients had received 100 mg leflunomide (then 20 mg/day in 807 cases), methotrexate (15-20 mg/day in 669 cases), sulphasalazine (2 g/day in 132 cases) and placebo (in 209 cases). HAQ scores and outcomes were assessed using the American College of Rheumatology core data set. Detailed statistical analyses were made of changes in outcome variables at 1 and 6 months, changes in HAQ scores at 1-12 months, and effect sizes for outcome variables at 6 and 12 months. Multiple regression models of changes in HAQ scores were evaluated using backwards stepwise linear regression.
Mean HAQ scores declined progressively with treatment with all three DMARDs. Changes occurred rapidly, and at month 1 were most pronounced with leflunomide. HAQ scores correlated closely with clinical response, as seen in changes in non-responders and ACR 20% and 50% responders. Regression analysis indicated that pain intensity and global assessments were significant determinants of HAQ.
HAQ scores are sensitive measures of effective DMARD therapy. HAQ may be especially useful early in the treatment process to assess patients' responses to DMARDs that show rapid onset of action, such as leflunomide.