Purpose: To analyze the impact of medical and social factors on survival and function from age 70 to 82 and point to possible genetic basis for differences.
Materials and methods: Longitudinal, cohort study of a representative sample of Jerusalem residents, born 1920-1921. At age 70, 463 subjects underwent a thorough interview eliciting social determinants as well as a medical history and examination and laboratory investigation. At age 77,265 of the survivors, 71%, were re-examined. In 2002, all death certificates in Israel were reviewed. End points were performance of basic and advanced tasks with ease at age 77 and survival to age 82 or life span in subjects who had succumbed. The independent influence of each factor was tested using logistic regression.
Results: 89.6% of women were alive after 6 years and 77.4% after 12. Survival for men was 79.9% and 59.8%, respectively. Social factors predominated in the correlation with longer life: financial security, p=.0004; volunteer activity, p=.0002; regular exercise, p=.0002; positive self-assessed health, p<.0001; and activities of daily living (ADL) independence, p<.0001. Less striking but significant correlation for longevity was noted for avoiding naps, p=.04 and instrumental activities of daily living (IADL) independence, p=.048. Medical conditions associated with increased mortality included diabetes, p<.0001; coronary artery disease, p=.0002; impaired vision, p=.0007; and renal insufficiency, p=.008. Anemia and disturbed sleep did not independently correlate with mortality while the association with hypertension did not reach statistical significance, p=.056. In a regression to determine the independent impact of medical and social factors on mortality, unimpaired renal function, good vision, avoiding afternoon naps, volunteer or compensated work, physical activity and IADL independence all correlated with improved survival. Moreover, good vision, volunteer work or work for pay and physical activity were independently associated with continued ADL independence after 7 years.
Conclusions: These findings highlight the ability of social, economic and functional factors to modify genetic influence on survival and function. Increased physical and social activity is an important tool to lengthen the span of robust function. The role of heredity in determining function and mortality may be expressed through diverse pathways.