Effect of smoking on the accumulation of deficits, frailty and survival in older adults: a secondary analysis from the Canadian Study of Health and Aging.

OBJECTIVES: Smoking has adverse effects on a variety of organ systems but little is known about the relationship between smoking and frailty. We aimed to investigate differences in health status between smoking and non smoking older adults.

DESIGN AND SETTING: The Canadian Study of Health and Aging, a nationally representative cohort study.

PARTICIPANTS: Nine thousand and eight community-dwelling men and women age 65 years and over at baseline.

MEASUREMENTS: Smoking status was determined using a Self-Assessed Risk Factor Questionnaire. Comparisons were made between never smokers, light smokers and heavy smokers with heavy smokers defined as those who smoked >or= 1 pack per day for 20 years or more. A frailty index (FI) generated from 40 self-reported health deficits was also modified to exclude 5 variables that could be directly attributed to smoking (e.g. cough). Decedent information was collected over 10 years.

RESULTS: Average FI values increased exponentially with age. For both men and women, heavy smokers were the most frail, light smokers had intermediate frailty status and never smokers were fittest. Modification of the FI did not impact these differences. Heavy smokers had significantly worse mortality than non smokers and higher rates of death in smokers persisted in the oldest old. 120 month survival curves, grouped for age, sex and smoking status showed that male smokers > 75 years had the highest mortality rates.

CONCLUSIONS: Smoking causes poorer health status at older ages which can be captured by the frailty index. Higher rates of death in smokers persist in the oldest old, with no emergence of "survivors" with fitness or longevity advantages.