Use of a microsimulation method for assessing dynamics of smoking status and gains in life expectancy after quitting in a longitudinal cohort of US older adults.

OBJECTIVES: Previous studies were unable to estimate the dynamics of smoking status in the US elderly general population, and no study has assessed the benefit of quitting in terms of resultant gains in life expectancy. We proposed a novel method to estimate the per cent of quitting in remaining lifetime, successful quitting and relapse, as well as life expectancy by participants' baseline smoking status.

DESIGN: Longitudinal cohort.

SETTING: US community-dwelling population.

PARTICIPANTS: Respondents from the Medicare Health Outcome Survey Cohort 15 (baseline 2012, follow-up 2014). We included respondents who were aged ≥65 years and alive at the baseline and participated in the baseline survey (n=164 597). Primary and secondary outcome measures Attempt quitting, successful quitting, relapse rates and life expectancy by smoking status at age 65-95 years.

RESULTS: Among daily smokers aged 65 years, 61% would attempt to quit during their remaining lifetime, and 31% would quit successfully. Among some days smokers aged 65 years, 69% would attempt to quit during their remaining lifetime, and 37% would quit successfully. Among recent ex-smokers aged 65 years, 53% would relapse. Life expectancy at age 65 years was 20.0 (SE=0.27), 17.2 (SE=0.30), 16.2 (SE=0.29) and 15.9 (SE=0.29) years for long time non-smokers, recent ex-smokers, some days smokers and daily smokers, respectively. Although recent ex-smokers had a higher 2-year mortality than current smokers, those who quit up to 77 years (77 years for men and 87 years for women) had a significantly longer (p<0.05) life expectancy. Sensitivity analysis demonstrated that the model assumptions had a relatively small impact on estimates with a maximum relative bias within ±7%.

CONCLUSIONS: This study provides detailed information regarding the dynamics of smoking status in an understudied and growing population and demonstrates the benefit of smoking cessation on life expectancy. Future research should focus on understanding specific predictors of smoking cessation.