Belimumab corticosteroid-sparing treatment in systemic lupus erythematosus: a real-life observational study (BESST study).

Data about the impact of Belimumab on corticosteroid sparing in real life are scarce. To assess the corticosteroid-sparing effect among patients with systemic lupus erythematosus (SLE) treated with Belimumab in real-life settings. Multicentric observational retrospective study including patients with SLE and having received Belimumab for at least 6 months between 2011 and 2020, in eight French hospitals. "Low dose" referred to patients receiving up to 7.5 mg of prednisone a day and "Very low dose" to those receiving strictly ≤ 5 mg prednisone a day The primary endpoint was the reduction of daily prednisone dose after six months of Belimumab. The secondary endpoint was a change in the proportion of patients with low or very low dose of prednisone as well as those without prednisone during the Belimumab course. Censoring occurred for patients who stopped Belimumab. Bivariate analyses were performed using the Wilcoxon signed-rank test. The threshold for statistical significance was set at p < 0.05. Thirty patients were included. All were female with a median age of 38 years. A significant reduction in prednisone dose was observed at month 6 (10 [7-20] vs 6.75 [2-9] mg, p < 0.0001), continued until month 12 (10 [7-20] mg vs 5 [0-7.12] mg, p < 0.001) and was sustained until month 24. The proportion of patients with very low dose of prednisone and those without prednisone progressively increased during the Belimumab course. Introducing Belimumab in patients with SLE, in real-life conditions, is associated with early and sustained corticosteroid-sparing effect.