SAT-412 TEN-YEAR TRENDS IN DIAGNOSIS OF KIDNEY DISEASES IN JAPAN -THE JAPAN KIDENY DISEASE REGISTRY/JAPAN RENAL BIOPSY REGISTRY (J-KDR/J-RBR)

Abstract

The incidence and age distribution of pathological diagnosis of kidney diseases vary throughout the world by race, ethnicity, environment and medical systems. Japanese Society of Nephrology (JSN) launched a nation-wide kidney disease registry, Japan kidney disease registry/Japan renal biopsy registry (J-KDR/J-RBR) in 2007. The aim of the present study was to clarify the ten-year trends of the pathological diagnosis of kidney disease among patients who underwent renal biopsy in Japan. Data were extracted from the database registered between July 2007 and June 2017. The number and rate of patients with various glomerular diseases including IgA nephropathy (IgAN), Henoch-Schönlein purpura nephritis (HSPN), and nephrotic syndrome (NS) were clarified and the trends were analyzed. The J-RBR is registered to the Clinical Trial Registry of UMIN (registered number UMIN000000618) and is available in Japanese and English. The data of cases (n=38, 318) registered in the J-RBR between July 2007 and June was extracted. The patients who underwent the first renal biopsy (n=20,139) were eligible for the first study. The number (the rates) of cases diagnosed with IgAN, HSPN, and NS were 6,322 (31%), 548 (2.7%), and 5,945 (30%), respectively. IgA vasculitis, including IgAN and HSPN, occupied 50% in 10 to 39 years old cases. The diagnosis of primary NS was made on 67% of total NS cases. The top pathological diagnosis of secondary NS was diabetic nephropathy, followed by lupus nephritis. Among primary NS, 44% was diagnosed with minimal change disease (MCD), 39% with membranous nephropathy (MN), and 11% with focal segmental glomerulosclerosis (FSGS). Most of the MN patients were over 40 years old while MCD and FSGS distributed widely to all ages. Of note, the substantial number of patients diagnosed with MCNS was over 70 years old. In the next study, we extracted the patients over 20 years old (n=30,935). Of these, IgAN occupied 30%, and primary NS occupied 15%. We analyzed the trends of pathological diagnosis. The rate of IgAN slightly decreased from 31% in 2008 to 27% in 2017. The rate of MCNS among primary NS was 32% at 2008, which gradually increased to 37% in 2013, and 43% in 2017. The rate of MN showed the similar levels: 46% in 2008 and 45% in 2017. When we analyzed age distribution, the peak of MN was at 60ies in 2009, while the peak had moved to 70ties by 2017. The rate of MPGN among NS patients markedly decreased from 10% in 2008 to 2.8% in 2017. The rate of FSGS varied each year between 9 to 12%, showing no clear trends. The age distribution of total cases registered in J-RBR showed a single peak at early 60 ties in 2009, which moved to late 60ites in 2016, suggesting the good association with the rapidly aging population in Japan. Nation-wide renal biopsy registry revealed the change in incidence of type of glomerular diseases in Japan. IgAN was the most common pathological diagnosis occupying about 30% of entire renal biopsy cases. The data indicate that incidence of IgAN and MPGN decreased, and that of MCNS increased in the past ten years, while the rate of MN was constant. One of the reasons for these trends may be attributable to the rapid change in the age distribution in Japan.