Idiopathic nephrotic syndrome in New Zealand children, demographic, clinical features, initial management and outcome after twelve-month follow-up: results of a three-year national surveillance study.

Objective: To describe the demographic, clinical features, steroid response, histopathology and complications of all children diagnosed with idiopathic nephrotic syndrome (INS) in New Zealand over a 3-year period.

Methods: A questionnaire seeking relevant clinical information was sent to all paediatricians who reported a new case of nephrotic syndrome to the New Zealand Paediatric Surveillance Unit. A follow-up questionnaire was sent to reporting paediatricians after the first 12 months of follow-up.

Results: The incidence was 1.9 children per 100,000 under age 15 years. There was no significant difference in INS between ethnic groups. Approximately 80.4% were steroid responsive with median time to response of 8.4 days and mean time to relapse was 15.1 +/- 12.1 weeks (10.1-19.8 95% confidence interval). Follow-up at 12 months after diagnosis showed that two-thirds were either steroid dependent or frequent relapsers. Steroid resistance patients had a more variable course with some developing chronic renal failure and other remaining persistently nephrotic.

Conclusions: The incidence and outcome of children with INS are similar to overseas studies. A large variety of steroid treatment regimens were noted. Current evidenced-based guidelines to treat INS were used infrequently.