Abstract
Background The EULAR/ERA-EDTA recommendations for lupus nephritis state that renal response should be achieved in 12 months following induction therapy. However, early predictors of renal outcome are not well established. We aim to identify baseline predictors of complete renal response (CRR).
Methods Retrospective cohort study over 36 months including patients with SLE fulfilling the ACR’97 and/or the SLICC’12 classification criteria and with a biopsy-proven proliferative lupus nephritis (class III/IV), enrolled in the CHUC Lupus Cohort. CCR was defined according to EULAR/ERA-EDTA definitions as proteinuria <0.5 g/day and normal renal function. Clinical-demographic characteristics at baseline were compared using survival analysis for time-to-CCR. Variables with p<0.25 on univariate analysis with Log-Rank tests and lupus nephritis histological class (III/IV) were further evaluated as potential predictors with multivariate Cox proportional hazards regression models (Backward Stepwise method) adjusting for potential confounding.
Results 56 patients were included in the analysis (76.8% female, age at baseline 30.0 ± 13.2 years-old). Over the follow-up period, 51 patients (91.1%) reached CCR, within a median time of 6.0 months. High blood pressure (p=0.047), no hydroxychloroquine therapy (p=0.012), induction treatment with cyclophosphamide (as compared to mycophenolate mofetil - MMF) (p=0.027) and proteinuria >2 g/day (p=0.008) were associated with longer time to CCR in univariate analysis. In multivariate analysis, proteinuria >2 g/day at baseline (HR 2.651; 95%CI 1.338–5.25; p=0.005) was a predictor of worse renal outcome, while induction therapy with MMF lead to shorter time to CCR as compared with cyclophosphamide (HR=0.525; 95%CI 0.277–0.998; p=0.049). Other variables lost significance and were not included in the final model. The addition of glucocorticoid pulses and/or antihypertensive drugs to induction therapy did not influence renal outcome.
Conclusions Most of the patients reached CCR during the follow-up period. Proteinuria above 2 g/day at baseline and use of cyclophosphamide as compared to MMF induction were associated with worse renal outcome.
