A Survey of Common Risk Factors and their Effects on Life Expectancy
The results of this epidemiological study don't include any great surprises, but do present a convenient summary of the effect sizes of some of the commonly assessed lifestyle and environmental factors known to influence long-term health and thus life expectancy. This means smoking, level of exercise, whether or not one is overweight, undergoing sustained psychological stress, and so forth. The largest missing factor is likely degree of exposure to persistent pathogens such as cytomegalovirus, but this data is challenging to obtain across large populations, and thus isn't present in epidemiological databases.
All of that said, the advent of practical, working rejuvenation therapies (such as senolytic treatments) will render these present variations in life expectancy largely irrelevant. In a world in which technological progress is ongoing, the pace of progress towards various means of treating aging as a medical condition will become the largest determinant of future life expectancy.
Most people want to live a long and healthy life. Choices affecting the prospects of achieving this goal are continually made by individuals themselves and by health professionals. Which amenable determinants of health and longevity should be emphasised in specific individual situations? It is well known from observational epidemiological studies that risk factors describing the sociodemographic background, lifestyles, dietary factors, life satisfaction (LS), and metabolic health predict mortality. For example, vigorous physical activity has been found to decrease the risk of death by 22% compared with no physical activity. Smoking has been found to increase the hazard by 83% and life dissatisfaction by 49%.
Comparisons between different risk factors and their impact on survival could be carried out using expected age of death (EAD) that is easier to interpret than commonly presented hazard ratios. Evidence-based decisions on how to improve the length of life, tailored to specific individual contexts, require reliable information on the EAD for different levels of these risk factors. In this study, we analyse total mortality using a model with a large number of risk factors that have previously been found to be predictors of longevity. The study assessed a otal of 38,549 participants aged 25-74 years at baseline of the National FINRISK Study between 1987 and 2007. The Primary outcome measures were register-based comprehensive mortality data from 1987 to 2014 with an average follow-up time of 16 years and 4310 deaths.
The largest influence on the EAD appeared to be a current smoker versus a never smoker as the EAD for a 30-year-old man decreased from 86.8 years, which corresponds to the reference values of the risk factors, to 82.6 years, and additionally, smoking 20 cigarettes per day decreased EAD further to 80.2 years while keeping all other risk factors at the same values. Diabetes decreased EAD almost as much to 80.3 years. Whole or full milk consumers had EAD of 84.5 years compared with 87.9 years of those consuming skimmed milk. Physically inactive men had EAD of 85.0 years whereas those with high activity had EAD of 87.4 years. Men, who found their life almost unbearable due to stress, had EAD of 84.0 years. For older men and for women the differences were similar but smaller.
BMI values below 22 and above 33, non-HDL cholesterol values below 3.6 and above 6.5, diastolic blood pressure above 85 and systolic blood pressure values below 110 and above 135 appeared to reduce the EAD when compared with the lowest risk values, but these optimal values are based on the other risk factors being at their optimal values. In practice, for example, overweight and obesity can increase blood pressure compared with normal weight, which can increase mortality.