Resistance factors for the treatment of immunoglobulin A nephropathy with diffuse mesangial proliferation

Aim Some patients with severe immunoglobulin A nephropathy (IgAN) are resistant to multi‐drug combination therapy; however, there have been few reports on the risk factors for non‐responsiveness to treatment for severe IgAN. We, therefore, evaluated the risk factors for non‐responsiveness to treatment in cases of severe IgAN. Methods We collected data on 44 children who had been diagnosed with IgAN with diffuse mesangial proliferation and treated with multi‐drug combination therapy. The children were divided into two groups based on the prognosis at the latest follow‐up. Group 1 consisted of 30 children with normal urine and nine children with minor urinary abnormalities and Group 2 consisted of four children with persistent nephropathy and one child with renal insufficiency. The clinical, laboratory, and pathological findings for both groups were analyzed. Results The age at the onset in Group 2 was higher than that in Group 1. C3 deposits and high chronicity index values at the first renal biopsy were more frequently found in Group 2 than in Group 1 patients. IgA deposits, serum IgA and myeloid‐related protein (MRP) 8/14 levels, and glomerular and interstitial MRP8+CD68+ scores at the second biopsy were all higher in Group 2 than in Group 1 patients. Conclusions Our results, although based on only a small number of patients in a retrospective study, suggest that age, presence of C3 deposits and interstitial changes at the onset, and persistent renal inflammatory activation may be risk factors for non‐responsiveness to treatment for IgAN with diffuse mesangial proliferation. Summary at a Glance This paper identifies a number of clinical, laboratory and pathological risk factors for persistence of IgA nephropathy despite treatment in children.