Risk Factors versus Lifestyle Choices in the Mortality of Old Age
Environmental and lifestyle choices, as numerous epidemiological studies have demonstrated, have considerable influence over health and mortality in late life. This open access paper balances lifestyle choices against a range of environmental factors and measures of the progression of aging. The authors find that a healthy lifestyle can only partially offset the effects of having a greater burden of age-related damage and its consequences, or, separately, the impact of low socioeconomic status. The former makes a great deal of sense, given the inevitability of aging as matters currently stand, with even the healthiest succumbing, while the latter is an interesting finding. It remains unclear as to the mechanisms linking socioeconomic status to aging: wealth, education, intelligence, stress, access to medical services, and other factors are closely tied and hard to pick apart in the human data.
Annual mortality among oldest-old individuals was reduced by somewhere between 0.2% and 1.3% from 1998 to 2008 in China. Impaired cognitive functions were independent predictors of all-cause mortality in very old people. Moreover, the risk of mortality is very high for the oldest-old with disabilities. Additionally, socioeconomic inequalities, obesity, cardiovascular factors, and chronic diseases are associated with mortality in the oldest-old. Conversely, healthy lifestyle practices, such as consumption of fruits and vegetables, social participation, and maintaining a normal weight, are associated with lower mortality. The question remains as to whether a healthy lifestyle and behavioral factors (e.g., never smoking and physical training) can somehow compensate for the harmful effects of the risk factors on mortality.
In this large, nationwide cohort study of Chinese oldest-old (80 years of age and older), we found that rural residence, not in marriage, lower economic level, physical disability, impaired cognitive function, and comorbidity are independent risk factors for mortality. Using these factors, we computed a weighted "risk score." Because never smoking, never drinking, doing physical exercise, having an ideal diet, and a normal weight were independently associated with lower mortality, we also combined them to compute a weighted "protection score." Both scores were divided into lowest, middle, and highest groups using their tertiles.
In joint effect analyses, participants with the combined highest-risk score and lowest-protection score profile had a nearly threefold higher joint death risk. These analyses show that adherence to a healthy lifestyle counteracts the negative effect of risk factors on all-cause mortality in the oldest-old by more than 20%.