Prognosis of proliferative lupus nephritis subsets in the Louvain Lupus Nephritis inception Cohort

Abstract

OBJECTIVE: The objective of this paper is to evaluate whether the different International Society of Nephrology/Renal Pathology Society (ISN/RPS) classes of proliferative lupus nephritis (LN) have a distinct baseline presentation, short-term response to immunosuppression (IS) and long-term prognosis. METHODS: Ninety-eight patients with new onset (first renal biopsy) ISN/RPS proliferative LN (Class III: n=24; IV-S: n=23; IV-G: n=51) were diagnosed at our institution between 1995 and 2012 (Louvain Lupus Nephritis inception Cohort). Their baseline renal parameters, primary response to IS at one year, survival and long-term renal outcome (mean follow-up: 77 months) were compared. RESULTS: At baseline, serum creatinine and 24-hour proteinuria were higher in Class IV-G, as was activity index on renal biopsy in Class IV-S and IV-G compared to III. Upon treatment, renal parameters improved with the same kinetics and to the same extent in the three pathological classes. On repeat renal biopsies (n=43), activity indices dropped similarly. Poor outcomes (death, end-stage renal disease, renal impairment defined by an eGFR <60 ml/min/1.73 m(2)) did not statistically differ between groups, although there was a trend toward more renal impairment at follow-up in Class IV-G compared to IV-S and III. Finally, the presence of even mild chronic lesions on baseline biopsy was clearly predictive of late renal outcome. CONCLUSION: Subsetting proliferative LN into Class III, IV-S and IV-G provides less clinically discriminant prognostic information than baseline chronicity index.