Geographic difference in the prevalence of chronic kidney disease among Japanese screened subjects: Ibaraki versus Okinawa.

Background: In Japan, there is a geographic difference in the prevalence of end-stage renal disease (ESRD). Few epidemiologic studies, however, have compared the prevalence of chronic kidney disease (CKD) among different geographic areas. Other than genetic factors, socioeconomic conditions and lifestyle are targets for modification.

Methods: We examined the prevalence of CKD among two large community-based screened populations, 40 years of age and older, in Japan: Ibaraki (N = 187,863) and Okinawa (N = 83,150). Prevalence of CKD was defined as an estimated glomerular filtration rate (eGFR) of less than 60 ml/min/1.73 m(2) using the coefficient modified abbreviated Modification of Diet in Renal Disease (aMDRD) study equation using a standardized serum creatinine value. CKD prevalence was compared among screenees with (+) or without (-) hypertension (systolic blood pressure > or =140 mmHg, diastolic blood pressure > or =90 mmHg) and hyperglycemia (plasma glucose > or = 126 mg/dl).

Results: Both male and female participants in Okinawa had a significantly lower prevalence of hypertension (-)/hyperglycemia (-) than did patients in Ibaraki. The prevalence of CKD in Okinawa was higher than that in Ibaraki among screenees with hypertension (-)/hyperglycemia (-), and highest among screenees with hypertension (+)/hyperglycemia (-).

Conclusion: The regional difference in CKD prevalence may underlie the variation in ESRD prevalence observed in Japan.