Functional disability and health-related quality of life in South Africans with rheumatoid arthritis and systemic lupus erythematosus

There is a paucity of data on the impact of chronic rheumatic diseases on functional disability and overall health-related quality of life (HRQOL) in Africans. Materials and methods: We compared Black South Africans (BSA) with rheumatoid arthritis (RA) (n=50) and systemic lupus erythematosus (SLE) (n=50) to geographically and ethnically matched controls cared for at a tertiary care facility. The modified health assessment questionnaire (mHAQ) and Medical Outcome Study short-form 36 (SF-36) scores and indices of disease activity and organ damage were collected from each group. Results: Compared to the controls, both the RA and SLE groups fared significantly worse in respect of all the domains and summary scales of the SF-36. Compared to the SLE group, the RA group scored significantly worse with respect to the mHAQ disability index (mHAQ-DI), physical function and bodily pain (BP) SF-36 subscales, and SF-36 summary physical component score (SF-PCS). In the RA group, both the mHAQ-DI and SF-PCS correlated strongly (p < 0.005) with the tender joint count, patient global assessment, 28-joint composite disease activity score, physician global assessment, and pain score. The SF-PCS showed only a weak inverse correlation with the swollen joint count (r=-0.29, p < 0.05). In the SLE group, the systemic lupus erythematosus disease activity index correlated inversely best with the SF-36 general health subscale (r=-0.56, p < 0.0001) and, to a lesser extent, with the mental health, BP, and vitality subscales, and SF-PCS and SF-mental component summary scores. Conclusion: Both RA and SLE have profound effects on HRQOL in BSA, with BP and physical disability particularly worse in RA patients. Disease activity, rather than organ damage or sociodemographic characteristics, correlates best with certain aspects of functional disability and HRQOL in both RA and SLE. Further longitudinal studies are needed to assess the clinical utility of measures of functional disability and HRQOL in this population.