Clinical Outcomes of Patients with SLE Treated with Belimumab, Without Versus With Prior Immunosuppressant Use: a US Claims Database Study.

Introduction: This study examined the benefit of belimumab as standard treatment in patients with systemic lupus erythematosus (SLE) treated without versus with immunosuppressants (IS) prior to belimumab initiation.

Methods: This retrospective cohort study (GSK Study 217537) used healthcare claims from the US Komodo Health Database from January 2015 to October 2023. Eligible adults had ≥ 1 inpatient or ≥ 2 outpatient SLE diagnosis codes, ≥ 1 belimumab claim (January 2017-October 2023; index date) and 24 months continuous data pre-index. Two cohorts were defined: those with ≥ 1 claim for non-IS SLE treatment (antimalarials, oral glucocorticoids [OGC] or biologics; non-IS cohort) or ≥ 1 claim for incident IS (IS cohort) within 12 months pre-index. Cohort comparability was assessed across the 12 months before non-IS/IS treatment, applying inverse probability of treatment weighting (IPTW) to adjust for confounding. Outcomes included OGC use, SLE flare rates and healthcare resource utilisation, compared using Cox, Poisson regression and logit models, respectively.

Results: Overall, 2190 and 2533 patients were included in IPTW-adjusted non-IS and IS cohorts, respectively. The non-IS cohort had a median (95% confidence interval [CI]) time to OGC discontinuation of 9.8 (8.2, 12.2) months versus 11.7 (10.5, 13.4) for the IS cohort, and a 30% higher likelihood of OGC discontinuation (hazard ratio [95% CI] 1.30 [1.11, 1.52]). The likelihood of OGC dose reduction and discontinuation or dose reduction alone was similar between cohorts. The non-IS versus IS cohort had a lower incidence rate ratio (IRR [95% CI]) of total (0.94 [0.92, 0.96]) and moderate (0.77 [0.74, 0.80]) SLE flares, with similar odds of SLE-related inpatient stays (odds ratio [95% CI] 1.12 [0.94, 1.34]) and emergency visits (1.02 [0.82, 1.27]).

Conclusion: In this large, retrospective, real-word study using IPTW adjustment, initiating belimumab without prior IS use was associated with OGC-sparing benefits and reduced incidence and severity of SLE flares.