Association of Adherence to Healthy Lifestyle Recommendations With All-Cause and Cause-Specific Mortality Among Former Smokers

IMPORTANCE The benefits of smoking cessation are well known, but former smokers have a higher health risk than never smokers. The impact of former smokers' engaging in other aspects of a healthy lifestyle is unclear. OBJECTIVE To assess the association between adherence to evidence-based lifestyle recommendations and mortality among former smokers. DESIGN, SETTING, AND PARTICIPANTS This prospective cohort study included 159 937 participants in the National Institutes of Health-AARP Diet and Health Study of older US adults who completed the baseline and risk factor questionnaires and self-identified as former smokers. Baseline questionnaires were mailed from 1995 to 1996. Data analysis was performed from November 2020 to November 2021. EXPOSURES Adherence to evidence-based lifestyle recommendations was scored for body weight (scores, 0-2), diet (scores, 0-3), physical activity (scores, 0-2), and alcohol intake (scores, 0-1) recommendations, with higher scores indicating better adherence. Individual lifestyle adherence scores were summed to make a total adherence score (scores, 0-8). MAIN OUTCOMES AND MEASURES The primary outcomes were all-cause and cause-specific mortality through December 31, 2019, with a mean (SD) follow-up of 18.9 (6.3) years. Hazard ratios (HRs) and 95% CIs were computed using a multivariable Cox proportional hazards regression model. RESULTS Among 159 937 former smokers (mean [SD] age, 62.6 [5.2] years; 106 912 [66.9%] male; 149 742 [93.6%] White), 86 127 deaths occurred. A higher total adherence score was associated with lower all-cause mortality (HR per unit increase, 0.95; 95% CI, 0.94-0.95). Compared with the lowest total adherence score category (scores, 0-2), the HRs for all-cause mortality were 0.88 (95% CI, 0.86-0.90) for scores of 3 to 4, 0.80 (95% CI, 0.79-0.82) for scores of 5 to 6, and 0.73 (95% CI, 0.71-0.75) for scores of 7 to 8. Associations were observed regardless of health status, comorbid conditions, the number of cigarettes participants used to smoke per day, years since cessation, and age at smoking initiation. When examined individually, the HRs for highest vs lowest adherence score were 0.86 (95% CI, 0.84-0.88) for body weight, 0.91 (95% CI, 0.90-0.93) for diet, 0.83 (95% CI, 0.81-0.85) for physical activity, and 0.96 (95% CI, 0.94-0.97) for alcohol intake recommendations. Participants with a higher total adherence score also had a lower risk of mortality from cancer, cardiovascular disease, and respiratory disease. CONCLUSIONS AND RELEVANCE In a large US cohort of former smokers, better adherence to healthy lifestyle recommendations was associated with lower mortality risk. These results provide evidence that former smokers may benefit from adhering to lifestyle recommendations, as do other groups.