[Idiopathic nephrotic syndrome in children: Incidence, clinical presentation, and outcome in the county of Gironde, France]

Abstract

Aims: To estimate the incidence and describe the clinical presentation and outcome (steroid responsiveness, clinical course, complications) of idiopathic nephrotic syndrome in children in a population-based retrospective study.

Methods: Using local registries and the hospital discharge diagnosis system from two centers, all new cases of idiopathic nephrotic syndrome were identified in Gironde (France) between January 1992 and May 2008. To estimate incidence, population-based denominators were obtained from the National Institute for Statistics and Economic Studies (INSEE). Clinical data were collected from medical charts.

Results: Ninety-nine cases of idiopathic nephrotic syndrome were reported (66 boys, 18 non-Caucasians) with an incidence of 2.3/100,000 (CI, 1.8-3.0) children less than 15 years. Ninety patients (91%) had steroid-sensitive nephrotic syndrome (SSNS) and nine (9%) were steroid-resistant (SRNS). The median time to remission in SSNS was 11 days. Relapses occurred in 75 (83%) children with SSNS with a median of four relapses (range, 1-32). The cumulative relapse-free incidence was 60% at 10 years after diagnosis in SSNS and 13% of patients aged 18 years old or over still had active disease. In SSNS, the only significant factor associated with steroid dependency or use of non steroid drugs was the time to initial response to steroids greater than 14 days. Nineteen children (19%) experienced severe complications of nephrotic syndrome including 11 bacterial infections and two thromboembolic complications. Two children with SRNS, of whom one was initially steroid-responsive, developed end-stage renal failure.

Conclusion: The incidence and outcome of idiopathic nephrotic syndrome in Gironde are comparable to the rates found in other studies. The disease may have a long course and the time for response to steroids at disease onset is the main predictor of steroid dependency and of use of non steroid agents.