Comparison of performance of specific (SLEQOL) and generic (SF36) health-related quality of life questionnaires and their associations with disease status of systemic lupus erythematosus: a longitudinal study

BACKGROUND: The utility of generic health-related quality of life (HRQoL) questionnaires in patients with systemic lupus erythematosus (SLE) is uncertain. We compared the performance of generic (SF36) and specific (SLEQOL) HRQoL surveys by examining their associations with the Global Rating of Change (GRC) and SLE clinical indicators. METHODS: The study included SLE patients who attended a single-center rheumatology clinic between 2013 and 2017. Patients completed both specific (SLEQOL) and generic (SF36) surveys and rated their GRC compared to the previous visit using a 7-point Likert scale on the same day of routine visits. Based on GRC scores, patients' change in HRQoL was categorized as "no change," "deterioration," or "improvement." Disease activity (SLEDAI-2K), flare, and lupus low disease activity state (LLDAS) were assessed at each visit, and organ damage (SDI) was determined annually. Pairwise correlations between SLEQOL and SF36 components were examined, and associations between GRC status and SLE disease indicators were compared using generalized estimating equations (GEE). RESULTS: Three hundred thirty-seven patients with 2062 visits were included in the analysis. SLEQOL correlated significantly with SF36. Patients reported improvements in HRQoL in 58%, deterioration in 15%, and "no change" in 27% of all visits. Compared to the "no change" group, mean SF36 and SLEQOL scores were significantly lower in the deterioration group and higher in the improvement group. The magnitude of changes observed with SLEQOL and SF36 in the deterioration and improvement groups was similar. Patients in LLDAS had significantly higher mean scores in both SLEQOL and SF36. In contrast, patients with active disease, especially those with cutaneous, renal, central nervous system, and musculoskeletal activity, had significantly lower SLEQOL and SF36. Flare and organ damage were also associated with lower SLEQOL and SF36-PCS (physical component) but not with SF36-MCS (mental component). CONCLUSION: SLEQOL and SF36 similarly describe HRQoL in SLE. Both instruments demonstrated strong associations with GRC-based deterioration or improvement as well as SLE disease status. LLDAS was associated with improved HRQoL.