Low birth weight and end-stage renal disease: demographic analysis by region in Japan.
BACKGROUND We have previously shown regional differences in the incidence of end-stage renal disease (ESRD)within Japan, which is ethnically homogenous, suggesting that non-genetic factors may contribute to the differences.We examined regional distribution in the incidence of low birth weight (LBW), a surrogate for low nephron number,in our search for an explanation.


METHODS
Each year, the Ministry of Health, Labour and Welfare of Japan and the Japanese Society for Dialysis Therapy report the number of LBW babies and patients initiating maintenance dialysis in each prefecture of Japan,respectively. In this study, we calculated the annual incidences of LBW and ESRD in 11 regions of Japan over a 24-year period from 1984 to 2007.


RESULTS
There were distinct regional differences in the annual incidences of both LBW and ESRD (p<0.0001).These regional distributions persisted despite consistent increases (p<0.0001) in incidences of both LBW and ESRD during the study period. Compared with the reference group consisting of 3 regions with the lowest LBW incidence, the odds ratios for ESRD (95% confidence interval) of the 5 regions with intermediate LBW incidence and the 3 regions with the highest LBW incidence are 1.09(1.05–1.14) and 1.29 (1.22–1.35), respectively. The annual incidence of LBW was positively correlated with annual incidence of ESRD in their regional distribution across 11 regions (r = 0.66, p = 0.03).


CONCLUSIONS
The present study, relating regional distribution between LBW and ESRD dynamics in a nationwide population of Japan, revealed that the marked regional differences in the incidence of ESRD within Japan could be explained by a similar regional distribution in the incidence of LBW.
Department of Cardio-Renal Medicine and Hypertension, Nagoya City University, Graduate School of Medical Sciences, Mizuho-ku, Nagoya 467-8601, Japan.
Tadashi
T
Ichikawa
Michio
M
Fukuda
Tamaki
T
Wakamatsu-Yamanaka
Ryo
R
Sato
Takehiro
T
Naito
Hiroyuki
H
Togawa
Yuji
Y
Sasakawa
Tatsuya
T
Tomonari
Masashi
M
Mizuno
Toshiyuki
T
Miura
Yoko
Y
Kato
Minamo
M
Ono
Yuichi
Y
Shirasawa
Akinori
A
Ito
Atsuhiro
A
Yoshida
Genjiro
G
Kimura
D006801:Humans; D015994:Incidence; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D007564:Japan / Q000453:epidemiology; D007676:Kidney Failure, Chronic / Q000453:epidemiology* / Q000209:etiology / Q000628:therapy; D006435:Renal Dialysis / Q000706:statistics & numerical data; D012307:Risk Factors