Association between body-mass index and risk of death in more than 1 million Asians

Abstract

Background: Most studies that have evaluated the association between the body-mass index (BMI) and the risks of death from any cause and from specific causes have been conducted in populations of European origin.

Methods: We performed pooled analyses to evaluate the association between BMI and the risk of death among more than 1.1 million persons recruited in 19 cohorts in Asia. The analyses included approximately 120,700 deaths that occurred during a mean follow-up period of 9.2 years. Cox regression models were used to adjust for confounding factors.

Results: In the cohorts of East Asians, including Chinese, Japanese, and Koreans, the lowest risk of death was seen among persons with a BMI (the weight in kilograms divided by the square of the height in meters) in the range of 22.6 to 27.5. The risk was elevated among persons with BMI levels either higher or lower than that range--by a factor of up to 1.5 among those with a BMI of more than 35.0 and by a factor of 2.8 among those with a BMI of 15.0 or less. A similar U-shaped association was seen between BMI and the risks of death from cancer, from cardiovascular diseases, and from other causes. In the cohorts comprising Indians and Bangladeshis, the risks of death from any cause and from causes other than cancer or cardiovascular disease were increased among persons with a BMI of 20.0 or less, as compared with those with a BMI of 22.6 to 25.0, whereas there was no excess risk of either death from any cause or cause-specific death associated with a high BMI.

Conclusions: Underweight was associated with a substantially increased risk of death in all Asian populations. The excess risk of death associated with a high BMI, however, was seen among East Asians but not among Indians and Bangladeshis.

Figure 1. Association between Body-Mass Index and Risk of Cause-Specific Death in Two Asian Populations

Hazard ratios are shown for the association between body-mass index (BMI, the weight in kilograms divided by the square of the height in meters) and risk of death from cardiovascular disease (CVD), from cancer, and from other causes among East Asians (Chinese, Japanese, and Koreans) and Indians and Bangladeshis. Panels A and B show the hazard ratios without confidence intervals, and Panels C and D show the same data with 95% confidence intervals (I bars). The analyses were adjusted for age, sex, educational level, urban or rural residence, marital status, and status with respect to baseline illnesses; data from subjects with less than 3 years of follow-up were excluded.

Figure 2. Association between the Body-Mass Index and the Risk of Death from Respiratory Diseases or Other Causes

Hazard ratios are shown for the association between BMI and risk of death from respiratory diseases and from causes other than respiratory diseases, cardiovascular causes, or cancer (other) among East Asians (Chinese, Japanese, and Koreans) and Indians and Bangladeshis. Panels A and B show the hazard ratios without confidence intervals, and Panels C and D show the same data with 95% confidence intervals (I bars). The analyses were adjusted for age, sex, educational level, urban or rural residence, marital status, and status with respect to baseline illnesses; data from subjects with less than 3 years of follow-up were excluded.