Long-term evaluation of chlorambucil plus prednisone in the idiopathic nephrotic syndrome of childhood.

We evaluated the long-term effects of a five to 15-week course of chlorambucil and prednisone in 59 children with idiopathic nephrotic syndrome who had previously received prednisone alone and had had frequent relapses or steroid dependency or resistance. By actuarial analysis of 65 courses of dual therapy followed up for one to 12 years (mean, 5.0), we found that 95 per cent of patients were in remission at one year and 85 per cent at four years. All but two had remissions lasting longer than those induced by steroids alone, and only eight others had one or more relapses after therapy. Life-table analysis of two dosage schedules of chlorambucil at four years showed that 91 per cent of patients on low doses and 80 per cent of those on high doses were still in remission. Although immediate complications were minimal, the potential for long-term toxicity still requires careful selection of patients who receive chlorambucil. Prolonged use of chlorambucil in daily doses above 0.3 mg per kilogram of body weight per day or cumulative doses above 14 mg per kilogram is no longer warranted. Measured in terms of both the immediate and long-term responses, chlorambucil appears to lower the frequency of relapses in idiopathic nephrotic syndrome.