The prevalence of IgAN varies across different geographical regions. According to the Japan Renal Biopsy Registry (J-RBR)1, which was started in 2007, about one-third of patients who undergo renal biopsy are diagnosed with IgAN. Most patients with IgAN in Japan are discovered from asymptomatic urinary abnormalities, because annual urinary screening is frequently this website performed. The majority of patients

with IgAN may thus be diagnosed in the early stage of the disease. Global consensuses in both diagnosis and treatment of IgAN have recently been reached. The Oxford classification of IgAN defined pathological features predicting risk of progression of renal disease in IgAN2,3. The Oxford classification is

useful for Japanese patients with IgAN4; however, due to its complexity, it has not been widely accepted in clinical practice. Version 3 of the Clinical Guideline for IgA Nephropathy has recently been published in Japan5, and histological classification based on a multicenter case-control study of IgAN in Japan has been suggested6. Kidney Disease: Improving Global Outcomes (KDIGO) published a clinical practice guideline for glomerulonephritis in 2011. For the management of IgAN, few randomized controlled trials (RCTs) have been undertaken and the sample sizes of those RCTs have been very small. Most advice relating to IgAN in the KDIGO guideline is thus based on a low quality of evidence7. Major potential treatment modalities for adult IgAN in Japan include renin-angiotensin system blockers, corticosteroids, non-steroidal immunosuppressive

agents, click here antiplatelet agents and n-3 fatty acids (fish oil), and tonsillectomy with corticosteroid pulse therapy (TSP). Notably, TSP was widely used in patients at risk of progressive disease before consensus was established. An RCT comparing TSP with steroid pulse therapy alone was recently completed, and preliminary results were reported at the 2011 annual meeting of the Japanese Society of Nephrology. With the accumulation of recent advances, guidelines for Japanese clinical practice need to be established. The IgAN guideline working group supported by the Japanese Ministry of Health, Labor and Welfare has compiled the first comprehensive Japanese guideline for mafosfamide IgAN using an evidence-based methodology as defined in Medical Information Network Distribution Service (Minds). This guideline only focuses on IgAN and covers the definition, pathogenesis, diagnosis, renal pathology, classification, epidemiology, prognosis, treatment, and adverse events of immunosuppression therapy. The working group created 14 clinical questions (CQs) for the treatment of adult and pediatric patients with IgAN. All statements and CQs were carefully reviewed by Japanese nephrologists, pathologists, pediatric nephrologists, and other specialists.