Newswise — Niigata, Japan - A new Japanese study reveals significant birth cohort effects on the incidence trend of ESKD requiring RRT.

A recent study conducted in Niigata, Japan has discovered notable birth cohort effects on the incidence trend of end-stage kidney disease (ESKD) requiring renal replacement therapy (RRT). According to Dr. Wakasugi, the corresponding author of the study, "Different birth cohorts may have varying levels of exposure to specific risk factors, resulting in changes in disease incidence among individuals born during a particular time, known as a cohort effect." The researchers utilized Age-Period-Cohort (APC) analysis, a statistical approach that distinguishes between age, period, and cohort effects, to identify which age groups or birth cohorts may require targeted interventions.

By analyzing data from the Japanese Society of Dialysis Therapy registry and national census spanning from 1982 to 2021, the study unveiled intriguing findings. The risk of incident renal replacement therapy (RRT) initially increased in certain birth cohorts, reached its peak, and subsequently declined in more recent birth cohorts for both males and females. However, the peaks varied by sex, with elevated trends peaking in the 1940s to 1960s for men and the 1930s to 1940s for women.

Dr. Wakasugi, the lead author of the study, stated, "Our findings indicate that men born in the 1940s to 1960s and women born in the 1930s to 1940s may be important target populations for interventions aimed at reducing the incidence rates of renal replacement therapy (RRT) among the Japanese population."

The study hypothesizes that the cohort effects on RRT incidence rates could be attributed to the impact of poor environmental conditions caused by wartime during birth. The nutrition of the Japanese population was severely compromised during World War II (1939-45) and the years that followed, which could have led to low birth weights and subsequently increased risks of hypertension, diabetes mellitus, cardiovascular disease, and chronic kidney disease. This hypothesis is supported by a previous study that used the Age-Period-Cohort (APC) model with Taiwan Renal Disease System Databases, which found that the birth cohort of 1943-47 (during World War II) had the highest risk of requiring dialysis compared to other birth cohorts.

However, the study also acknowledges that this explanation may not fully account for the high risk of incident RRT among men born in the 1960s, suggesting that other factors could be at play. Further research is needed to uncover the precise reasons behind the observed cohort effects on RRT incidence rates in different birth cohorts and sexes in Japan.

Journal Link: Clinical and Experimental Nephrology