Association of body mass index and weight change with all-cause mortality in the elderly

Abstract

The authors explored the relation of body mass index (BMI; weight (kg)/height (m)(2)) and weight change to all-cause mortality in the elderly, using data from a large, population-based California cohort study, the Leisure World Cohort Study. They estimated relative risks of mortality associated with self-reported BMI at study entry, BMI at age 21 years, and weight change between age 21 and study entry. Participants were categorized as underweight (BMI <18.5), normal weight (BMI 18.5-24.9), overweight (BMI 25-29.9), or obese (BMI >or=30). Of 13,451 participants aged 73 years (on average) at study entry (1981-1985), 11,203 died during 23 years of follow-up (1981-2004). Relative to normal weight, being underweight (relative risk (RR) = 1.51, 95% confidence interval (CI): 1.38, 1.65) or obese (RR = 1.25, 95% CI: 1.13, 1.38) at study entry was associated with increased mortality. People who were either overweight or obese at age 21 also had increased mortality (RR = 1.17, 95% CI: 1.09, 1.25). Participants who lost weight between age 21 and study entry had increased mortality regardless of their BMI category at age 21. Obesity was significantly associated with increased mortality only among persons under age 75 years and among never or past smokers. This study highlights the influence on older-age mortality risk of being overweight or obese in young adulthood and underweight or obese in later life.

FIGURE 1

Relative risk of all-cause mortality according to body mass index (BMI; weight (kg)/height (m)²) category at study entry for never, past, and current smokers, Leisure World Cohort Study, 1981–2004. Results were adjusted for gender and age at entry. The normal weight category within each smoking group was used as the reference category. Bars, 95% confidence interval.

FIGURE 2

Relative risk of all-cause mortality according to body mass index (BMI; weight (kg)/height (m)²) category at study entry for different age groups at entry, Leisure World Cohort Study, 1981–2004. Results were adjusted for gender and smoking status. The normal weight category within each age group was used as the reference category. Bars, 95% confidence interval.