Predictors of renal flares in systemic lupus erythematosus: a post-hoc analysis of four phase III clinical trials of belimumab

Abstract Objective The objective of this study was to identify predictors of renal flares in patients with SLE treated for active extra-renal disease. Methods Data from four clinical trials of belimumab in SLE (BLISS-52, NCT00424476; BLISS-76, NCT00410384; BLISS-NEA, NCT01345253; BLISS-SC, NCT01484496) were used. Patients were assigned to belimumab or placebo on top of standard therapy. We investigated the performance of predictors of renal flares through weeks 52–76 using proportional hazards regression analysis. Results Of 3225 participants, 192 developed at least one renal flare during follow-up, with the first occurring after a median time of 197 days. Current/former renal involvement [hazards ratio (HR): 15.4; 95% CI: 8.3–28.2; P < 0.001], low serum albumin levels (HR 0.9; 95% CI: 0.8–0.9; P < 0.001), proteinuria (HR: 1.6; 95% CI: 1.5–1.7; P < 0.001), and low C3 levels (HR: 2.9; 95% CI: 2.1–4.1; P < 0.001) at baseline appeared robust determinants of impending renal flares. Anti-dsDNA positivity yielded an increased hazard for renal flares (HR: 2.1; 95% CI: 1.4–3.2; P < 0.001), which attenuated after adjustments. Anti-Sm positivity was associated with renal flares in the placebo (HR: 3.7; 95% CI: 2.0–6.9; P < 0.001) but not in the belimumab subgroup, whereas anti-ribosomal P positivity was associated with renal flares in the belimumab subgroup only (HR: 2.8; 95% CI: 1.5–5.0; P = 0.001). Conclusion A history of renal involvement, high baseline proteinuria, hypoalbuminaemia, and C3 consumption were robust determinants of impending renal flares. In addition to anti-dsDNA, anti-Sm and anti-ribosomal P protein antibody positivity may have value in surveillance of renal SLE.