Former smokers may additionally lower their risk of premature death by more than 25% by adhering to healthy lifestyle recommendations, according to a new large prospective cohort study led by researchers at the National Cancer Institute (NCI), part of the National Institutes of Health (NIH).
“I was surprised to see the robust associations [with lifestyle],” said lead author Maki Inoue-Choi, PhD, of the Division of Cancer Epidemiology and Genetics at NCI, in a NIH press release. “Former smokers who adhered to evidence-based recommendations for body weight, diet, physical activity, and alcohol intake had a lower risk of mortality than former smokers who didn't adhere to these recommendations.”
The benefits of smoking cessation are well known, but former smokers are at higher risk for poor health than never smokers, observe Inoue-Choi and colleagues. They also point out that the impact of engaging in other aspects of a healthy lifestyle on former smokers’ overall health remains unclear. The team aimed to assess the association between adherence to evidence-based lifestyle recommendations and mortality among former smokers.
The analysis included 159 937 participants (mean age, 62.6 years; 66.9% men; 93.6% White) in the National Institutes of Health-AARP Diet and Health Study who completed questionnaires regarding lifestyle, demographics, and other health-related information between 1995 and 1996. The participants were followed for approximately 19 years, during which time 86 127 participants died. Death information, including cause of death, came from the National Death Index.
For each participant, investigators calculated a total adherence score ranging from no adherence to full adherence. The total adherence score incorporated individual scores for body mass index, based on guidelines from the World Health Organization; for dietary quality, based on the Dietary Guidelines for Americans, 2010-2015; for physical activity, based on the Physical Activity Guidelines for Americans, second edition; and for alcohol use, based on the Dietary Guidelines for Americans, 2020-2025.
Results showed that participants who had the highest total adherence scores had a 27% lower risk of death from any cause than those with the lowest scores. Also, former smokers with the highest adherence scores had a 24% decrease in risk of cancer-related mortality, 28% decrease in risk of death from cardiovascular disease, and 30% reduction in risk of death from respiratory disease. These decreases in risk of death were observed regardless of health status, other health conditions, how many cigarettes participants used to smoke daily, years since they quit smoking, and age they started smoking, according to the study.
In addition, Inoue-Choi et al examined the benefits of adherence for individual lifestyle recommendations. They observed that in each case, participants with the highest adherence score had a lower risk of mortality compared to those with the lowest score:
“To have the greatest benefit, it is better to adhere to many lifestyle recommendations,” stated Inoue-Choi in the release. “But even those who adopted just a single lifestyle recommendation experienced benefit.”
The team noted a few limitations to their analysis, including the fact that as an observational study, “residual and unmeasured confounding is of concern, especially by smoking patterns and underlying health conditions.” Also, participants were predominantly White and had relatively higher socioeconomic status than the general US population, so researchers noted that future studies should be performed in more diverse populations.