Association between Immunoglobulin M and steroid resistance in children with nephrotic syndrome: A retrospective multicenter study in Japan

Background: The prognosis of steroid resistant nephrotic syndrome (SRNS) in children is poorer than steroid-sensitive cases. The diagnosis is made following the response to the initial 4-week corticosteroid therapy, which might be accompanied by side effects. However, predictive indicators at initial diagnosis remain unknown. We aimed to investigate whether selectivity index (SI) and other indicators at initial diagnosis, for example, serum immunoglobulin M (IgM) and total serum protein albumin ratio (TA ratio, total serum protein level over albumin level), can predict SRNS. Methods: Eighty children were enrolled from seven hospitals in Japan between January 2008 and December 2019 (mean age 4.7; male 65.0 %). Of the enrolled 80 children, 13 (16.3 %, M:F = 5:8) had been diagnosed as steroid-resistant after the initial treatment with steroids. The association between serum IgM (tertile categories; low: 24-133; middle: 134-169; and high: 169.1-510 mg/dl), SI (