Socioeconomic Disparities in Electronic Cigarette Use and Transitions from Smoking.

Introduction: Socioeconomic disparities have been established for conventional cigarette use, but not for electronic cigarettes. This study estimates socioeconomic gradients in exclusive use of conventional cigarettes, electronic cigarettes, and dual use (i.e., use of both products) among adults in the United States.

Methods: Analyses consider nationally representative data on 25 to 54 year old respondents to the 2014-2016 National Health Interview Surveys (N=50,306). Demographically-adjusted seemingly unrelated regression models estimate how two socioeconomic status measures- respondent education and household income- relate to current exclusive use of conventional cigarettes, electronic cigarettes, and dual use.

Results: Conventional cigarette use exhibits negative education and income gradients, consistent with existing research: -12.8 percentage points [CI: -13.9, -11.7] if college educated, and -9.4 percentage points [CI: -10.8, -7.9] if household income exceeds 400% of the federal poverty level. These gradients are flatter for dual use (-1.3 [CI: -1.8, -0.8] and -1.8 [CI: -2.4, -1.2]), and statistically insignificant for electronic cigarette use (-0.03 [CI: -0.5, 0.4] and -0.3 [CI: -0.8, -0.2]). Limiting the sample to ever-smokers, higher education is associated with a 0.9 percentage point increase in likelihood of exclusive electronic cigarette use [CI: 0.0, 1.9].

Conclusions: Education and income gradients in exclusive electronic cigarette use are small and statistically insignificant, contrasting with strong negative gradients in exclusive conventional cigarette use. Furthermore, more educated smokers are more likely to switch to exclusive e-cigarette use than less educated smokers. Such differential switching may exacerbate socioeconomic disparities in smoking-related morbidity and mortality, but lower the burden of tobacco-related disease.