Body mass index, weight change and mortality in the elderly. A 15 y longitudinal population study of 70 y olds

OBJECTIVE: To examine the relationship between body mass index (BMI) at age 70, weight change between age 70 and 75, and 15 y mortality.

DESIGN: Cohort study of 70-y-olds.

SETTING: Geriatric Medicine Department, Göteborg University, Sweden.

SUBJECTS: A total of 2628 (1225 males and 1403 females) 70-y-olds examined in 1971--1981 in Gothenburg, Sweden.

RESULTS: The relative risks (RRs) for 15 y mortality were highest in the lowest BMI quintiles of males 1.20 (95% CI 0.96--1.51) and females 1.49 (95% CI 1.14--1.96). In non-smoking males, no significant differences were observed across the quintiles for 5, 10 and 15 y mortality. In non-smoking females, the highest RR (1.58, 95% CI 1.15--2.16) for 15 y mortality was in the lowest quintile. After exclusion of first 5 y death, no excess risks were found in males for following 5 and 10 y mortality across the quintiles. In females, a U-shaped relation was observed after such exclusions. BMI ranges with lowest 15 y mortality were 27--29 and 25--27 kg/m(2) in non-smoking males and females, respectively. A weight loss of > or = 10% between age 70 and 75 meant a significantly higher risk for subsequent 5 and 10 y mortality in both sexes relative to individuals with 'stable' weights.

CONCLUSION: Low BMI and weight loss are risk factors for mortality in the elderly and smoking habits did not significantly modify that relationship. The BMI ranges with lowest risks for 15 y mortality are relatively higher in elderly. Exclusion of early deaths from the analysis modified the weight-mortality relationship in elderly males but not in females.