Context Despite recent medical advances, the number of patients beginning dialysis
annually is increasing in both the United States and Japan. The ethnically
homogeneous population of Japan presents an opportunity to study the presence
of factors other than race/ethnicity that might contribute to incidence of
end-stage renal disease (ESRD).
Objective To determine if and where regional differences exist in ESRD in Japan.
Design, Setting, and Subjects Analysis of data reported by the Japanese Society for Dialysis Therapy
based on the annual number of patients with ESRD beginning maintenance dialysis
therapy in all 47 prefectures of Japan from 1982 to 1998.
Main Outcome Measures Mean annual ESRD incidence and increasing rate of ESRD in each of 11
predefined areas making up the entire country.
Results Incidence of ESRD increased approximately 3-fold in Japan during the
study years, from 81.3 per 1 million in 1982 to 237.6 per 1 million in 1998.
Significant regional differences were found in both measures. The mean (SEM)
annual ESRD incidence (P<.01) and increasing rate
of ESRD (P<.01), respectively, were significantly
different across Japan. Koshinetsu (140  per 1 million and 9.1 [0.6] per
1 million/y) and Hokuriku (141  per 1 million and 9.7 [0.5] per 1 million/y)
were the areas with the lowest incidence and increasing rate of incidence,
while Okinawa (188  per 1 million and 13.4 [0.6] per 1 million/y) and
Kyushu (179  per 1 million and 12.0 [0.6] per 1 million/y) were the areas
with the highest incidence and increasing rate of incidence.
Conclusions We found definite and significant regional differences in incidence
and increasing rate of incidence of ESRD in Japan. Further analyses are needed
to identify factors that contribute to these regional differences and thereby
improve strategies for treatment of renal disease.