Health-related quality of life and disease activity in rheumatoid arthritis

BACKGROUND: The present study sought to 1) investigate the degrees of correlations between different disease activity scores (DASs) and health-related quality of life (HRQoL), and 2) determine if DASs correlate with either physical or mental HRQoL. METHODS: Eighty patients with rheumatoid arthritis (RA) were assessed for different DASs, measured with erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP), namely DAS4-ESR, DAS-3 ESR, DAS4-CRP, DAS3-CRP, DAS4-28 ESR, DAS3-28 ESR, DAS4-28 CRP, and DAS3-28 CRP, and Simplified Disease Activity Indexes namely SDAI-ESR, and SDAI-CRP. Physical and mental HRQoL were measured using the SF-36. The Pearson correlation test was employed to examine the correlations between HRQoL and different DAS indices. PASS 2000 (Power Analysis and Sample Size) software was utilized to find significant differences between the correlations. RESULTS: SF-36 total score showed a significant inverse correlation with the DAS4-ESR, DAS-3 ESR, DAS4-CRP, DAS3-CRP, DAS4-28 ESR, DAS3-28 ESR, DAS4-28 CRP, and DAS3-28 CRP, with correlation coefficients of -0.320, -0.314, -0.330, -0.323, -0.327, -0.318, -0.360 and -0.348, respectively (P < 0.01 for all). The correlation coefficients between different DAS indices and the HRQoL score were not significantly different. In addition, all DASs showed significant correlations with physical HRQoL, but not with mental HRQoL. CONCLUSIONS: Among patients with RA, disease severity indices are associated with physical, but not mental HRQoL. However this study failed to show any differences between various DASs in their clinical use.