RESUMEN
BACKGROUND: The Japan Renal Biopsy Registry (J-RBR), a nationwide, web-based, registry system, started in 2007. This study aimed to summarise the epidemiology of biopsy-diagnosed kidney disease in Japan over 10 years. METHODS: We analysed the J-RBR database, from 2007 to 2017. Patients' clinical data collected at the time of biopsy and histopathological diagnoses were used for epidemiological and clinicopathologic analyses. RESULTS: The predominant renal biopsy diagnoses were immunoglobulin A nephropathy (39.2%), lupus nephritis (6.5%) and minimal change disease (6.0%) in younger adults (19-64 years), and membranous nephropathy (17.4%), antineutrophil cytoplasmic antibody-associated vasculitis or anti-glomerular basement membrane glomerulonephritis (13.0%), and immunoglobulin A nephropathy (12.5%) in older adults (≥ 65 years). The percentages of patients diagnosed with membranoproliferative glomerulonephritis and immunoglobulin A nephropathy decreased, whereas those with immunoglobulin A vasculitis and diabetic nephropathy increased over the decade. In paediatric patients (< 19 years), immunoglobulin A nephropathy (36.1%), minimal change disease (17.6%), and immunoglobulin A vasculitis (8.6%) were the predominant diagnoses. The percentage of patients diagnosed with immunoglobulin A vasculitis increased over the decade. Based on the sex distribution, minimal change disease and membranous nephropathy were predominant in men aged < 20 and > 40 years, respectively, whereas immunoglobulin A vasculitis and antineutrophil cytoplasmic antibody-associated vasculitis or anti-glomerular basement membrane glomerulonephritis were predominant in women in their 20s and 30s and aged < 50 years, respectively. Immunoglobulin A nephropathy was predominant in men at most ages and in women in their 20s to 40s. CONCLUSIONS: This study describes the distribution and changes in kidney biopsy diagnoses over 10 years in Japan and paves the way for future research on kidney diseases in adults and children.