Increasing incidence of dialysis among the elderly in Japan: An analysis based on cohort vs. census incidence

[Background] Japan has the world-highest prevalence of dialysis with one out of 464 people are on dialysis (cf. US: 1/1000). The number of dialysis patients is growing due not only to population ageing but also to the increasing “incidence” among the elderly.

[Methods] From the statistics published by Japan Society for Dialysis Therapy, age-sex-specific incidence per 100,000 population were compared between 2002 and 2007. Comparison was made between the cohort incidence and census (cross-sectional) incidence for five-years age groups. The cohort of 65-69 years old in 2002 will be 70-74 yo in 2007. If their incidence in 70-74 yo in 2007 is lower than the incidence for the age group of 70-74 yo in 2002, it can be inferred that their incidence was lowered due to prevention. Otherwise, the cohort of 65-69 yo in 2002 showed a deteriorated incidence in the following five years.

[Results] Cohort incidence was lower than census incidence for women in cohorts younger 75 years old in 2002 but higher for cohorts of 75 years or older. For men, cohort incidence was higher than census incidence in cohorts of 40-44, 50-54 and 65-84 yo in 2002. The male cohort of 70-74 yo had the incidence of 114.3 per 100,000 in 2002 and 143.4 in 2007 when they became 75-79 yo. This figure was higher than 126.8 of 75-79 yo in 2002.

[Conclusions] Incidence of dialysis is increasing among the elderly in Japan particularly for men suggesting urgent preventive measures against kidney failures.