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 (ie, 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 = 50306). 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: -12.9 percentage points (confidence interval [CI]: -14.0, -11.8) if college educated, and -9.5 percentage points (CI: -10.9, -8.1) if household income exceeds 400% of the federal poverty level. These gradients are flatter for dual use (-1.4 [CI: -1.8, -0.9] and -1.9 [CI: -2.5, -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 at interview (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. IMPLICATIONS: Research has not yet established whether socioeconomic disparities in electronic cigarette (e-cigarette) use resemble those observed for conventional cigarettes. This article uses nationally representative data on US adults aged 25-54 to estimate income and education gradients in exclusive use of conventional cigarettes, e-cigarettes, and dual use. Both gradients are steep and negative for conventional cigarette use, but flat and statistically insignificant for e-cigarette use. Repeating the analysis among ever-smokers indicates that more educated smokers are more likely to transition toward exclusive e-cigarette use than less educated smokers. Such differential substitution may exacerbate disparities in smoking-related morbidity and mortality.