OBJECTIVES: To examine the association between body mass index (BMI) and mortality in older people.
DESIGN: A longitudinal cohort study of an age-homogenous, representative sample born in 1920/21.
SETTING: Community-based home assessments.
PARTICIPANTS: West Jerusalem residents born in 1920/21 examined at baseline in 1990 (n=447), with additional recruitment waves in 1998 (n=870) and 2005 (n=1,086).
MEASUREMENTS: Comprehensive assessment of health variables including BMI (m/kg2) at ages 70, 78, and 85. The primary outcome of mortality was collected from age 70 to 88 (1990–2008). Adjusted Cox proportional hazards analysis was used to calculate hazard ratios (HRs) for mortality according to unit increase in BMI.
RESULTS: A unit increase in BMI in women resulted in HRs of 0.94, (95% confidence interval (CI)=0.89–0.99) at age 70, 0.95 (95% CI=0.91–0.98) at age 78, and 0.91 (95% CI=0.86–0.98) at age 85. Similarly, in men, HRs were 0.99 (95% CI=0.95–1.05) at age 70, 0.94 (95% CI=0.91–0.98) at age 78, and 0.91 (95% CI=0.86–0.98) at age 85. A time-dependent analysis of 450 subjects followed for 18 years confirmed the above findings; a unit increase in BMI resulted in HRs of 0.93 (95% CI=0.87–0.99) in women and 0.93(95% CI=0.88–0.98) in men. Eliminating the first third of follow-up mortality to account for possibility of reverse causality did not change the results.
CONCLUSION: Higher BMI was associated with lower mortality from age 70 to 88.