Incidence and relapse of idiopathic nephrotic syndrome: Meta-analysis

CONTEXT: Idiopathic nephrotic syndrome (INS) in children is a disease with considerable morbidity, yet the incidence and risk for relapse have not been systematically reviewed. OBJECTIVE: To estimate the overall pooled weighted incidence and risk for relapse of INS in children. DATA SOURCES: Medline and Embase (until December 2020). STUDY SELECTION: All studies reporting incidence (per 100 000 children per year) and/or risk for relapse (the proportion of patients who experience $1 relapse) of INS in children (age: <18 years) were eligible. DATA EXTRACTION: After quality assessment, data were extracted: study (design, localization, and sample size) and patient (age, sex, steroid response, and ethnicity) characteristics, incidence, and risk for relapse. RESULTS: After screening, 73 studies were included for analysis (27 incidence, 54 relapse). The overall pooled weighted estimate and corresponding prediction interval (PI) of the incidence was 2.92 (95% PI: 0.00–6.51) per 100 000 children per year. Higher incidences were found in non-Western countries (P < .001). Incidence tended to be lower in white children, but this was not significant. The overall pooled weighted estimate of the risk for relapse was 71.9% (95% PI: 38.8–95.5). Between 1945 and 2011, incidence did not change (P 5 .39), yet the risk for relapse decreased significantly (P 5 .024), from 87.4% to 66.2%. LIMITATIONS: There was no full-text availability (n 5 33), considerable heterogeneity, and limited studies from Africa, Latin America, and Asia. CONCLUSIONS: INS has a low incidence with ethnic variation but high risk for relapse. Although corticosteroids have significantly reduced the risk for relapse, it remains unacceptably high, underscoring the need for alternative treatment strategies.