Summary of the Okinawa Dialysis Study from 1971 to 2020 (OKIDS50)

Abstract

We have been conducting a clinical epidemiological study on chronic dialysis patients in Okinawa, Japan. We defined those who survived at least one month on scheduled dialysis or underwent kidney transplantation as chronic dialysis patients (end-stage kidney disease, ESKD). Chronic dialysis treatment was started in June 1971, and there are currently 74 dialysis units. Previously, we reported the demographics of dialysis patients in OKIDS20 (1971-1990) and predictors of survival in OKIDS30 (1971-2000). In OKIDS30, the rate of transfer outside Okinawa was only 1.2％ (N＝61). The 1-, 5-, 10-, and 20-year cumulative survival rates were 88.6％, 66.5％, 48.2％, and 29.3％, respectively. There were 1,982 and 5,246 registered patients in 1990 and 2000, respectively. In OKIDS50, it is expected that there will be around 13,500 registered patients. According to the 2020 annual report from the Japanese Society for Dialysis Therapy, the prevalence of dialysis patients per million population was 3232 in Okinawa and 2754 in Japan, respectively. Among the potential predictors of survival other than sex；age；primary renal disease；and comorbid conditions, such as stroke and acute myocardial infarction, variables related to malnutrition, such as low serum albumin and cholesterol levels, and high serum C-reactive protein levels were found to be significant. We also investigated the predictors of developing ESKD by combining the OKIDS and general screening registries. The most potent predictor of ESKD was dipstick-positive proteinuria；the 10-year cumulative incidence was 10％ and 5％ in patients with dipstick proteinuria scores of ≥3＋ and 2＋, respectively. Other significant predictors were dipstick hematuria, hypertension, obesity, a low hematocrit level (males：＜40％, females：＜35％), and hyperuricemia. Upon completion of the OKIDS50, we will consider the historical changes in the primary renal diseases, incidence, prevalence, and survival of chronic dialysis patients and compare them to the changes in the background population of Okinawa.