The burden of mortality of obesity at middle and old age is small: A life table analysis of the US Health and Retirement Survey

The evidence of effect of overweight and obesity on mortality at middle and old age is conflicting. The increased relative risk of cardiovascular disease and diabetes for overweight and obese individuals compared to normal weight is well documented, but the absolute risk of cardiovascular death has decreased spectacularly since the 1980s. We estimate the burden of mortality of obesity among middle and old aged adults in the Health and Retirement Survey (HRS), a US prospective longitudinal study. We calculate univariate and multivariate age-specific probabilities and proportional hazard ratios of death in relation to self-reported body mass index (BMI), smoking and education. The life table translates age specific adjusted event rates in survival times, dependent on risk factor distributions (smoking, levels of education and self reported BMI). 95% confidence intervals are calculated by bootstrapping. The highest life expectancy at age 55 was found in overweight (BMI 25-29.9), highly educated non smokers: 30.7 (29.5-31.9) years (men) and 33.2 (32.1-34.3) (women), slightly higher than a BMI 23-24.9 in both sexes. Smoking decreased the population life expectancy with 3.5 (2.7-4.4) years (men) and 1.8 (1.0-2.5) years (women). Less than optimal education cost men and women respectively 2.8 (2.1-3.6) and 2.6 (1.6-3.6) years. Obesity and low normal weight decreased population life expectancy respectively by 0.8 (0.2-1.3) and 0.8 (0.0-1.5) years for men and women in a contemporary, US population. The burden of mortality of obesity is limited, compared to smoking and low education.