Five-year outcome of children with idiopathic nephrotic syndrome: the NEPHROVIR population-based cohort study.

Background: The optimal therapeutic regimen for children at onset of idiopathic nephrotic syndrome (INS) is still under debate. A better knowledge of the disease's course is necessary to design more appropriate and/or personalized treatment protocols.

Methods: We report the 5-year outcome of patients included from December 2007 to May 2010 in the prospective multicentric and multiethnic population-based NEPHROVIR study. Patients were treated at onset according to the French steroid protocol (3990 mg/m, 18 weeks). Data were collected at 5 years or last follow-up.

Results: Out of the 188 children with nephrotic syndrome (121 boys, 67 girls; median age 4.1 years), 174 (93%) were steroid-sensitive. Six percent of steroid-sensitive patients required intravenous steroid pulses to get into remission. Relapse-free rate for steroid-sensitive patients was 21% (36/174) at last follow-up (median 72 months). A first relapse occurred in138 steroid sensitive patients (79%) with a median time of 8.3 months (IQ 3.4-11.3). Out of the 138 relapsers, 43 were frequent relapsers. Age at onset below 4 years was the only predictive factor of relapse, while gender, ethnicity, and delay to first remission were not. At 96 months of follow-up, 83% of frequent relapsers were still under steroids and/or immunosuppressive drugs.

Conclusions: The treatment of the first flare deserves major improvements in order to reduce the prevalence of relapsers and the subsequent long-lasting exposure to steroids and immunosuppression.