Prognostic effect of body mass index to mortality in Korean older persons

Body mass index (BMI) is regarded as a predictor of life expectancy and a determinant of mortality. However, the effect of age on BMI-related mortality remains unclear. The aim of the present study was to examine the prognostic effect of BMI to mortality risk among Korean older persons.

Data were collected from the Korean National Health Insurance Services' Senior Cohort database. This study analyzed the data of 79 341 men and 91 298 women aged ≥65 years who underwent health examinations in the 2007 fiscal year. Individual mortality was identified 5 years after 2008. The participants were stratified into seven groups according to basal BMI. Hazard ratios of death were calculated through Cox proportional hazards model after adjusting for age, sex, smoking status, exercise, alcohol intake and income.

During the 5-year follow up, 11 651 men and 7 235 women died. In both sexes, a lower BMI had a higher hazard ratio (HR), but the trend of increasing HR at high BMI was not clear. For men, the lowest HR was 0.79 (95% CI 0.71-0.87) at a BMI of 27.5-30.0 kg/m² . For women, the lowest HR was 0.84 (95% CI 0.78-0.91) at a BMI of 25.0-27.5 kg/m² . For both sexes, the relative mortality risk was associated with a lower BMI.

A high BMI is not associated with increased mortality in older adults aged ≥65 years, whereas a lower BMI is associated with an increased mortality risk in later life in this population. Geriatr Gerontol Int 2018; 18: 538-546.