To Örebro University

OBJECTIVES: 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 52-76 weeks 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 (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 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. Beyond anti-dsDNA, anti-Sm and anti-ribosomal P protein antibody positivity may have value in surveillance of renal SLE.