Age- and gender-specific BMI in terms of the lowest mortality in Japanese general population.
OBJECTIVE
The primary purposes of our study were to establish age- and gender-specific BMIs in terms of lowest mortality (risk nadir BMIs) for the Japanese population, and to then compare those to (i) BMIs for whites as determined by similar studies and to (ii) the official BMI guidelines.


METHODS
A total of 32,060 men and 61,916 women aged 40-79 years underwent health check-ups in Ibaraki prefecture, Japan, in 1993 and were followed through 2003. To determine the age- and gender-specific risk nadir BMIs, coefficients and the lowest point from a quadratic model with transformed BMI were calculated by a Cox proportional hazard model. This included the quadratic term of 1/BMI and adjusted values (age, alcohol intake, and smoking status).


RESULTS
For both age and both gender categories, the relationship between all-cause mortality risk and BMI categories are illustrated as U-shaped curves. The risk nadir BMIs for men in the age groups of 40-59 and 60-79 years were 23.4 and 25.3 kg/m(2), respectively. Similarly, in women, the risk nadir BMIs were 21.6 and 23.4 kg/m(2), respectively.


CONCLUSIONS
Among the general Japanese population, the risk nadir BMI for the age group of 60-79 years was higher compared to the age group of 40-59 years, which was similar to the study for whites, and the age-dependent risk nadir BMI differed from the official guidelines criteria. Our findings underscore the importance of weight control following appropriate indicators of body weight according to age.
Matsuo
Tomoaki
T
Ibaraki Health Service Association, Ibaraki, Japan.
Sairenchi
Toshimi
T
Iso
Hiroyasu
H
Irie
Fujiko
F
Tanaka
Kiyoji
K
Fukasawa
Nobuko
N
Ota
Hitoshi
H
Muto
Takashi
T
D000328:Adult; D017677:Age Distribution; D000367:Age Factors; D000368:Aged; D044466:Asian People / Q000706:statistics & numerical data; D015992:Body Mass Index; D005260:Female; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009026:Mortality / Q000639:trends; D009765:Obesity / Q000208:ethnology / Q000401:mortality* / Q000503:physiopathology; D017410:Practice Guidelines as Topic; D016016:Proportional Hazards Models; D011446:Prospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D017678:Sex Distribution; D012737:Sex Factors; D044465:White People / Q000706:statistics & numerical data