Trends in the incidence of renal replacement therapy due to rapidly progressive glomerulonephritis in Japan, 2006–2021

Niigata, Japan - A new Japanese nationwide study revealed that from 2006 to 2021, the number of patients with incident renal RRT due to RPGN increased, with an increase in the age-specific incidence of RRT due to RPGN in the older age groups (≥70 years old). Given the increasing trend in the incidence of RRT in older age groups and the ongoing population aging in Japan, the number of patients with incident RRT due to RPGN is likely to continue to increase in the future.

"RPGN is clinical syndrome that causes a rapid loss of kidney function, usually within a few days to a few weeks," said Dr. Wakasugi, the corresponding author of the study. "The survival and renal prognosis of Japanese patients with RPGN has improved in recent years. An improved renal prognosis in patients with RPGN would decrease the incidence of RRT due to RPGN, whereas an improved survival may increase the number of patients who progress to end-stage kidney disease (ESKD), resulting in an increase in the incidence of RRT due to RPGN. To date, no study has evaluated the trends in the incidence rates of RRT due to RPGN in Japan."

Using data from the Japanese Society of Dialysis Therapy registry and national census, the study revealed that the number and crude rates of patients with incident RRT due to RPGN increased in both sexes. The standardized incidence ratios significantly decreased initially relative to the first period (2006–2009) but gradually increased thereafter. Age-specific incidence rates in the older age groups (≥70 years old) also initially decreased in the period 2010–2013 but increased thereafter, peaking in the period 2018–2021. Given the increasing trend in the incidence of RRT in older age groups and the ongoing population aging in Japan, the number of patients with incident RRT due to RPGN is likely to continue to increase in the future.

"Although the exact reasons for these changes are unclear, several advances were made in the diagnosis and treatment of RPGN during the study period in Japan," said Dr. Wakasugi. "For example, evidence-based clinical guidelines for RPGN were first published in Japanese in 2014 with updates in 2017 and 2020 and in English in 2016 and updated in 2021. In addition, many therapeutic agents for RPGN are now covered by insurance in Japan, including rituximab, a chimeric monoclonal antibody targeting the pan-B-cell marker CD20 for anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (covered since 2013), plasma exchange for anti- anti-glomerular basement membrane (GBM) nephritis (covered since 2016), and ANCA-associated vasculitis (covered since 2018). Furthermore, RPGN and anti-GBM nephritis have been specified as intractable diseases ("Nanbyo" in Japanese) since 2015 to promote research to clarify the pathogenesis of these diseases and develop pharmaceutical products and medical devices targeting them. These changes may have contributed to the improvement in the survival of patients with RPGN, especially in older age groups, in recent years."