MO484: Gender Differences in the Incidence of End-Stage of Renal Disease in Okinawa
Authors: Fukuhara Chisato , Kohagura Kentaro , Iseki Kunitoshi 
Published: May 2022

Abstract

BACKGROUND AND AIMS
The incidence of chronic kidney disease (CKD) and its progression to end-stage renal disease (ESRD) differ between genders, so it can be surmised that the incidence of ESRD is different between males and females. Acceptance of dialysis therapy may not necessarily be equal to the incidence of ESRD. Factors such as socio-economic conditions of the family, residential area, risk factors and compliance to the treatment of CKD are not equal among gender. We accessed the gender difference in incidence of ESRD and its risk factors in Okinawa, Japan, a major ESRD epidemic area.

METHOD
The Okinawa Dialysis Study (OKIDS) registry included all chronic dialysis patients treated in Okinawa, Japan, since 1971. We defined the ESRD as those who survived at least one month on scheduled dialysis therapy (hemodialysis and peritoneal dialysis) to exclude acute kidney injury. We analyzed the annual incidence of ESRD by gender for 30 years from 1971 to 2000. The incidence rate of ESRD was calculated as the number of incident dialysis patients divided by the census population of the previous year in each gender and expressed per million population (pmp). The number of dialysis facilities increased from 1 (1971) to 50 (2000). The census population was increased from 939 742 (1971) to 1 318 220 (2000) in Okinawa.

RESULTS
A total of 5264 patients, 2981 males and 2265 females, have initiated maintenance hemodialysis during the study period. The incidence rate of ESRD increased from 8.9 to 370 pmp in males and from 0 to 227 pmp in females between 1971 and 2000. The growth was fast and consistent throughout the period in males, while in females, the growth has become slower since 1990. After age-standardized, a similar trend was observed, which increased from 41 to 224 pmp in males and from 36 to 154 pmp in females between 1975 and 2000. For males and females, the age-specific incidence rate in the 60–79 year and &gt;80 year groups increased rapidly, and that in the 40–59 year group increased gradually, whereas in the 0–39 year group have been flat. The age-specific rate in the 60–79 year and &gt;80 year groups for males continued to increase throughout the period, while that for females peaked between 1990 and 1995. In the cause-specific incidence rate, the following trends were observed in males and females. The incident rate caused by chronic glomerular nephropathy increased from the 1970s to the 1980s and then leveled off, while that by diabetic nephropathy increased from the 1980s and that by nephrosclerosis increased from the 1990s. The marked growth was seen in the incident rate caused by diabetic nephropathy for both males and females. The rate increased 31 times for males and 12 times for females in the 20 years from 1981 to 2000. The age- and cause-specific incidence rate has risen remarkably among male diabetic nephropathy in &gt;60 years.

CONCLUSION
In Okinawa, the incidence rate of ESRD has increased significantly in males compared with females, and the gender difference has been widening. It was suggested that the increase in the number of males with diabetic nephropathy over the age of 60 contributed to this widening of the gender difference.