Real-world effectiveness of belimumab and anifrolumab in systemic lupus erythematosus: comparable trends in disease activity and glucocorticoid reduction.

Despite the proven efficacy of belimumab and anifrolumab for SLE, their relative effectiveness remains uncertain owing to conflicting indirect comparison studies. We conducted a comparative effectiveness study using multicenter health records to evaluate the adjusted 12-month changes in the SLE Disease Activity Index 2000 (SLEDAI-2K), glucocorticoid dose, anti-DNA antibody titers, and CH50 levels, along with the adjusted hazard ratios of discontinuation and adverse events. A total of 58 bionaïve lupus patients (belimumab: 36, anifrolumab: 22) who initiated belimumab or anifrolumab on or after January 1, 2022 were identified and followed for up to 2 years. Adjusted changes in the SLEDAI-2K, glucocorticoid dose, and anti-DNA antibody titers were similar, with between-group differences (belimumab - anifrolumab) of -0.4 SLEDAI-2K units (95% CI: -4.8, 4.0), 1.4 mg/day (95% CI: -5.1, 7.9), and -2.7 IU/mL (95% CI: -27, 21), respectively. Belimumab was associated with a greater increase in adjusted CH50 levels (between-group difference: 5.3 CH50/mL, 95% CI: -8.9, 20) and a lower adjusted hazard ratio of discontinuation (0.68, 95% CI: 0.12, 3.7). Infection was the most common adverse event (belimumab: 31%, anifrolumab: 41%). Our findings suggest both treatments provide similar effectiveness, with belimumab offering potential benefits in CH50 levels, treatment continuity, and infection risk.