Long-Term Effects of Cyclophosphamide in Sustained Remission in Childhood Steroid-resistant Nephrotic Syndrome

Nephrotic syndrome (NS) is a chronic renal disease that can progress into end-stage renal disease within 5 years if no remission occurs. Achieving optimal remission is important to obtain better outcomes of treating childhood steroid-resistant NS (SRNS). This study aimed to determine the survival, long-term outcomes, and factors associated with the sustained remission of SRNS patients after cyclophosphamide therapy. We retrospectively studied 33 children (24 boys) with SRNS treated with cyclophosphamide therapy over 2 years. Relapse-free survival was estimated using the Kaplan-Meier method. The determinants of long-term remission were assessed by univariate and multivariate analyses using Cox's proportional hazard models. The median age at the onset of NS was 3.0 years (range: 7 months to 14.0 years). The median age at the initiation of cyclophosphamide therapy was 5.0 years (range: 1.0-15.0 years). The mean cumulative cyclophosphamide dose was 155.61 ± 16.31 mg/kg body weight. In total, 18 of 33 (54.5%) children remained in remission for 2 years after cyclophosphamide therapy, and 10 of 15 patients who relapsed (66.67%) became steroid sensitive. Relapse-free survival after cyclophosphamide therapy was 78.8%, 69.7%, and 54.5% after 6, 12, and 24 months, respectively. Cox's proportional hazard regression identified no association between remission 2 years after cyclophosphamide therapy and other factors, such as age at the onset of SRNS, type of resistance, hypertension, hematuria, administration route of cyclophosphamide, and cumulative dose (all P >0.05). Cyclophosphamide therapy appeared to be beneficial for children with SRNS for sustaining 2-year remission with a 54.5% relapse-free survival rate.