title: Trajectories of Body Mass Index and Their Associations With Mortality Among Older Japanese: Do They Differ From Those of Western Populations?
abstract: Few studies have focused on the relationship between the trajectories of long-term changes in body mass index (BMI; weight (kg)/height (m)(2)) and all-cause mortality in old age, particularly in non-Western populations. We evaluated this association by applying group-based mixture models to data derived from the National Survey of the Japanese Elderly, which included 4,869 adults aged 60 or more years, with up to 7 repeated observations between 1987 and 2006. Four distinct BMI trajectories were identified: "low-normal weight, decreasing" (baseline BMI = 18.7; 23.8% of sample); "mid-normal weight, decreasing" (baseline BMI = 21.9; 44.6% of sample); "high-normal weight, decreasing" (baseline BMI = 24.8; 26.5% of sample); and "overweight, stable" (baseline BMI = 28.7; 5.2% of sample). Survival analysis with an average follow-up of 13.8 years showed that trajectories of higher BMI were associated with lower mortality. In particular, relative to those with a mid-normal weight, decreasing BMI trajectory, those with an overweight, stable BMI trajectory had the lowest mortality, and those with a low-normal, decreasing BMI trajectory had the highest mortality. In sharp contrast with prior observations from Western populations, BMI changes lie primarily within the normal-weight range, and virtually no older Japanese are obese. The association between BMI trajectories and mortality varies according to the distribution of BMI within the population.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Murayama
authors.forename: Jersey
authors.initials: J
authors.lastname: Liang
authors.forename: Joan M
authors.initials: JM
authors.lastname: Bennett
authors.forename: Benjamin A
authors.initials: BA
authors.lastname: Shaw
authors.forename: Anda
authors.initials: A
authors.lastname: Botoseneanu
authors.forename: Erika
authors.initials: E
authors.lastname: Kobayashi
authors.forename: Taro
authors.initials: T
authors.lastname: Fukaya
authors.forename: Shoji
authors.initials: S
authors.lastname: Shinkai
mesh_terms: D000368:Aged; D044466:Asian People / Q000706:statistics & numerical data*; D015992:Body Mass Index; D005260:Female; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009026:Mortality
keywords: Japan; body mass index; mortality; older adults; trajectories