Association between health-related quality of life and clinical efficacy endpoints in rheumatoid arthritis patients after four weeks treatment with anti-inflammatory agents.
BACKGROUND: Improvement of health-related quality of life (QoL) is increasingly recognized as a maj or treatment goal for patients with rheumatoid arthritis (RA). There are several measures of general health status and of physical functioning for assessing treatment effects on QoL in patients with RA, however, the relationship between QoL outcomes and conventional clinical efficacy endpoints is not completely understood. OBJECTIVE: To describe the association between changes in QoL and changes in other efficacy measures, among patients with RA after four weeks of treatment with etoricoxib, naproxen or placebo, and to explore differences in the association of changes in efficacy and changes in QoL parameters across treatment groups. METHODS: The study used data from 1684 patients with RA enrolled in two identical clinical trials (one US and one multinational). Patients were randomized to placebo, etoricoxib 90 mg once daily, or naproxen 500 mg twice daily in a 2 : 2: 1 allocation ratio. Primary efficacy endpoints were tender joint count, swollen joint count, patient global assessment of disease activity (100 mm VAS), and investigator global assessment of disease activity (0 - 4 Likert scale). QoL assessments were based on the Health Assessment Questionnaire (HAQ) and the Medical Outcomes Survey Short Form 36 (SF-36). Mean differences between baseline and week four were calculated for each parameter studied. Linear regression analysis was performed to assess the association between changes in clinical efficacy and changes in QoL parameters, adjusted for covariates. RESULTS: The degree of association between changes in tender or swollen joint counts and changes in QoL variables was low, explaining less than 10% of the variability for most QoL variables, except bodily pain (SF-36). In contrast, changes in patient global assessment of disease activity explained 33% of the variability in the overall HAQ score, and in the physical component score (SF-36; adjusted regression models). Values for investigator global assessment of disease activity were below those for patient global assessment but above joint count measures. Results were similar between the etoricoxib, naproxen and placebo groups in the degree of association between changes in efficacy and QoL variables. CONCLUSION: Currently used efficacy endpoints are less than ideal predictors of change in QoL. There is no evidence from this study that the association between changes in CE endpoints and QoL was different across treatments. Our results highlight the need to assess both conventional efficacy measures and QoL in clinical trials of RA treatments.