Smoking and the Reduced Life Expectancy of Individuals With Serious Mental Illness

Abstract

Introduction: People with serious mental illness experience substantially reduced life expectancy, likely due in part to their higher smoking rates relative to the general population. However, the extent to which smoking affects their life expectancy, independent of mental illness, is unknown. This study quantifies the potential contribution of smoking to reduced life expectancy among individuals with serious psychological distress (SPD), a measure that screens for serious mental illness in national surveys.

Methods: A cohort of 328,110 U.S. adults was examined using the 1997-2009 National Health Interview Surveys linked to the 2011 National Death Index. Cox models were used to estimate mortality hazard ratios for current smoking, former smoking, and SPD and construct life tables by smoking and SPD status. The smoking-attributable fraction of deaths by SPD status was calculated. Analyses were conducted in 2015.

Results: Among those with SPD, being a current smoker doubles the risk of death. Current smokers with SPD lose 14.9 years of life relative to never smokers without SPD. Among never smokers, having SPD reduces life expectancy by 5.3 years. Thus, smoking may account for up to two thirds of the difference in life expectancy between smokers with SPD and never smokers without SPD. One third of deaths among those with SPD can be attributed to smoking.

Conclusions: The life expectancy difference between current smokers with SPD and never smokers without SPD is primarily due to smoking. Aiding individuals with serious mental illness to avoid smoking will translate into sizeable gains in life expectancy.