Association of body mass index with all-cause mortality in the elderly population of Taiwan: A prospective cohort study.

ABSTRACT

BACKGROUND AND AIMS: The nutritional status of the elderly is different from that of young people. Body composition changes as people age, for example, fat mass increases, muscle mass decreases, and body fat distribution is changed. We aimed to investigate the association of body mass index (BMI) with cause-specific mortality in the elderly population. METHODS AND RESULTS: The data of annual health examination for the older citizens (≥65 years old) from 2006 to 2011 in Taipei City Hospital were used. Information on baseline demographics, lifestyle behaviors, medical, and drug usage were collected by a self-administered questionnaire. Cause-specific mortality was ascertained from the National Registration of Death. Individuals were followed up until death or December 31, 2012, whichever was earlier. Univariable and multivariable Cox proportional hazard analyses were applied to investigate the association between BMI and all-cause mortality. Among 81,221 older people included in the analysis, 42,602 (52.45%) were men. The mean age was 73.85 ± 6.32 years. Among the 81,221 participants, 3398 (4.18%) were underweight, 36,476 (44.91%) were normal weight, 25,708 (31.65%) were overweight, and 15,639 (19.25%) were obese. Those in the BMI category 27 ≤ BMI<28 kg/m2 had the lowest all-cause mortality risk. The BMI of lowest cause-specific mortality was between 27 kg/m2 and 28 kg/m2 in infection mortality, between 28 kg/m2 and 29 kg/m2 in circulation mortality, between 29 kg/m2 and 30 kg/m2 in respiratory mortality, and between 31 kg/m2 and 32 kg/m2 in cancer mortality. CONCLUSIONS: The current study found a J-shaped relation between BMI and cause-specific mortality in the elderly population of Taiwan.