The effect of aging on functional decline among older Japanese living in a community: a 5-year longitudinal data analysis.
OBJECTIVE
Using longitudinal data analyses, we examined the effects of aging on functional decline, based on activities of daily living (ADL) and instrumental activities of daily living (IADL) during a 5-year follow-up among older people living in a community in Japan.


METHODS
The baseline survey in July 1988 involved all elderly residents aged 60 or older in Saku City, Nagano, Japan (N=13418). All survivors of this cohort were asked to participate in follow-up surveys conducted in 1989, 1990, 1991, 1992 and 1993. Five items of ADL and five of IADL were measured on each survey. A generalized estimating equations (GEE) analysis was used to examine the effects of aging on the increase of the proportion of subjects with functional dependence.


RESULTS
These results indicated that the proportion of subjects who were dependent in ADL increased during the 5-year period by 2.2 times (p<0.001) and the proportion of those who were dependent in either ADL or IADL increased during the same period by 1.8 times (p<0.001). Gender did not appear to be significantly associated with functional decline.


CONCLUSIONS
The GEE analysis in this study identified the statistically significant effect of aging on the increase of the proportion of subjects with functional dependence based on ADL and IADL.
Ishizaki
Tatsuro
T
Department of Healthcare Economics and Quality Management, School of Public Health, Kyoto University Graduate School of Medicine, Kyoto, Japan. tatsuro@pbh.med.kyoto-u.ac.jp
Kai
Ichiro
I
Kobayashi
Yasuki
Y
Matsuyama
Yutaka
Y
Imanaka
Yuichi
Y
D000203:Activities of Daily Living; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging; D015331:Cohort Studies; D004185:Disability Evaluation; D005260:Female; D005500:Follow-Up Studies; D016852:Housing for the Elderly; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D014505:Urban Population / Q000706:statistics & numerical data