Impact of Healthy Lifestyle Factors on Life Expectancies in the US Population.
Level 3 - non-randomized controlled study
Prospective non-randomized cohort study combined with life-table demographic modeling
PubMed 29712712 · doi:10.1161/CIRCULATIONAHA.117.032047
What was done
Data from two prospective cohorts—the Nurses' Health Study (1980–2014; n=78,865 women) and the Health Professionals Follow-up Study (1986–2014; n=44,354 men)—were analyzed over up to 34 years of follow-up. Five low-risk lifestyle factors were defined: never smoking, normal body mass index (18.5 to 24.9 kg/m²), at least 30 min/day of moderate-to-vigorous physical activity, moderate alcohol intake, and high diet quality (top 40%). Hazard ratios for mortality were estimated and applied via life-table methods to US population data (NHANES 2013–2014 and CDC WONDER mortality rates) to project life expectancy at age 50.
What was found
Over follow-up, 42,167 deaths were documented. Comparing individuals with 5 versus 0 low-risk lifestyle factors, multivariable-adjusted hazard ratios were 0.26 (95% CI, 0.22–0.31) for all-cause mortality, 0.35 (95% CI, 0.27–0.45) for cancer mortality, and 0.18 (95% CI, 0.12–0.26) for cardiovascular disease mortality. The population-attributable risk of nonadherence to all 5 factors was 60.7% (95% CI, 53.6–66.7) for all-cause mortality. Projected life expectancy at age 50 was 43.1 years versus 29.0 years for women (difference of 14.0 years; 95% CI, 11.8–16.2) and 37.6 years versus 25.5 years for men (difference of 12.2 years; 95% CI, 10.1–14.2) comparing 5 versus 0 low-risk factors.
Why it matters
This study quantifies the cumulative longevity benefits of multiple low-risk lifestyle factors, demonstrating that adherence to five healthy habits is associated with more than a decade of additional life expectancy at age 50 in the US population.
Limits
The primary cohort populations consisted entirely of health professionals, which may limit generalizability. Lifestyle factors were self-reported, introducing potential measurement error, and residual confounding cannot be completely ruled out despite multivariable adjustment.
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- context A long-term Harvard study of World War II veterans showed that following core healthy lifestyle habits can extend average lifespan by up to 14 years.