Long-term outcome after cyclophosphamide treatment in children with steroid-dependent and frequently relapsing minimal change nephrotic syndrome

Background: Seventy percent of children with minimal change nephrotic syndrome (MCNS) have a steroid-dependent or frequent relapsing course of the disease, and most are treated with cyclophosphamide. We describe the clinical course of children with biopsy-proven MCNS treated with cyclophosphamide for steroid-dependent or frequently relapsing nephrotic syndrome at our institution from 1971 to 2003. Methods: From our pathology registry, we identified 93 patients with biopsy-proven MCNS who received cyclophosphamide therapy. Follow-up information from medical records and mailed questionnaires could be obtained for 80 patients (86%). Results: Only 35% of patients experienced no relapse after cyclophosphamide therapy. Twenty-one patients subsequently were treated with cyclosporine, with only 3 (14%) achieving persistent remission. At the end of follow-up, 23 patients (25%) still experienced relapse, and all except 3 patients required continuous immunosuppressive therapy. However, the cumulative incidence of persistent complete remission (>2 years without medication) increased over time (35% at 2 years, 52% at 6 years, and 71% at 15 years after the start of cyclophosphamide therapy), and no patient developed kidney failure. By means of univariate analysis, age younger than 3 years at onset predicted a lower likelihood of attaining remission (P < 0.05). Conclusion: More than a quarter of a selected group of cyclophosphamide-treated patients with steroid-dependent or frequently relapsing MCNS were not in remission after puberty and required prolonged immunosuppressive treatment. There is an urgent need for more effective treatment modalities resulting in persistent remission in these patients.