Aging, health risks, and cumulative disability

Persons with lower health risks tend to live longer than those with higher health risks, but there has been concern that greater longevity may bring with it greater disability. We performed a longitudinal study to determine whether persons with lower potentially modifiable health risks have more or less cumulative disability.

We studied 1741 university alumni who were surveyed first in 1962 (average age, 43 years) and then annually starting in 1986. Strata of high, moderate, and low risk were defined on the basis of smoking, body-mass index, and exercise patterns. Cumulative disability was determined with a health-assessment questionnaire and scored on a scale of 0 to 3. Cumulative disability from 1986 to 1994 (average age in 1994, 75 years) or death was the measure of lifetime disability.

Persons with high health risks in 1962 or 1986 had twice the cumulative disability of those with low health risks (disability index, 1.02 vs. 0.49; P<0.001). The results were consistent among survivors, subjects who died, men, and women and for both the last year and the last two years of observation. The onset of disability was postponed by more than five years in the low-risk group as compared with the high-risk group. The disability index for the low-risk subjects who died was half that for the high-risk subjects in the last one or two years of observation.

Smoking, body-mass index, and exercise patterns in midlife and late adulthood are predictors of subsequent disability. Not only do persons with better health habits survive longer, but in such persons, disability is postponed and compressed into fewer years at the end of life.