Authors
Ishii T. Momose Y. Esaki H. Une H.
Institution
Department of Hygiene and Preventive Medicine, School of Medicine, Fukuoka
University.
Title
[A prospective study on the relationship between body
mass index and mortality
in middle-aged and elderly people in Japan]. [Japanese]
Source
Nippon Koshu Eisei Zasshi - Japanese Journal of Public Health. 45(1):27-34,
1998 Jan.
Abstract
We conducted a prospective study to clarify the relationship between
mortality and body mass
index (BMI) in a middle-aged and elderly population in
Japan. The subjects included 12,649 people (5,686 males and 6,963 females)
aged from 40-69 years, who were identified by a mail survey between 1987 and
1989, and thereafter were followed up from the date of the survey until
February 28, 1995. Cox's proportional hazards model was used to adjust for
age, smoking status, drinking habit and occupation, and hazard ratios were
calculated for total mortality and cancer
mortality based on levels of BMI, while using a BMI of 22 to
approximately 24 as a reference level. Results showed a U shaped relationship
between BMI and total mortality in females. Females
demonstrated a minimal total mortality in the reference
group, but a significantly high hazard ratio in the lowest group of BMI < 20
(hazard ratio = 1.95, p < 0.01) and the highest group of BMI > or= 26 (hazard
ratio = 1.71, p < 0.01). On the other hand, males did not demonstrate such a
U shaped relationship, but instead showed an L shaped relationship between
BMI and total mortality. Males showed a minimal total
mortality at a BMI of 24 of approximately 26 (hazard ratio =
0.92), but a significantly high hazard ratio in the lowest BMI group (hazard
ratio = 1.57, p < 0.01). In contrast, an elevated hazard ratio was not
observed in the highest BMI group (hazard ratio = 1.05). The relationship
between BMI and cancer mortality was found to be similar to
the relationship between BMI and total mortality in both
males and females. Our findings suggest that moderate overweight may be a
sign of good health among both middle-aged and elderly men in Japan.