E-cigarettes and Smoking Cessation in the United States According to Frequency of E-cigarette Use and Quitting Duration: Analysis of the 2016 and 2017 National Health Interview Surveys

Introduction: The purpose of this study was to examine the association between electronic cigarette (e-cigarette) use and smoking cessation among US adults. Duration of smoking cessation was taken into consideration because e-cigarette awareness and use were low in the United States before 2010.

Methods: A pooled analysis of the 2016 and 2017 National Health Interview Surveys on current (N = 9935) and former smokers (N = 14 754) was performed. Adjusted prevalence ratios (aPRs), for sociodemographic factors, were calculated.

Findings: Current e-cigarette use was reported by 10.5% (95% CI = 9.8% to 11.3%) of current smokers and 4.5% (95% CI = 4.0% to 5.0%) of former smokers. Prevalence was high in former smokers of less than 1 year (16.8%, 95% CI = 13.9% to 20.2%), 1-3 years (15.0%, 95% CI = 13.0% to 17.3%), and 4-6 years (10.5%, 95% CI = 8.6% to 12.7%), and very low in former smokers of more than 6 years (0.7%, 95% CI = 0.5% to 0.9%). Similar patterns were observed for daily e-cigarette use. Current e-cigarette use was negatively associated with being a former smoker when quit duration was ignored (aPR = 0.64, 95% CI = 0.59 to 0.69) but was positively associated with being a former smoker of less than 1 year (aPR = 1.44, 95% CI = 1.12 to 1.84) and 1-3 years (aPR = 1.21, 95% CI = 1.03 to 1.42). Daily e-cigarette use was not associated with being a former smoker when quit duration was ignored but was positively associated with being a former smoker of less than 1 year (aPR = 3.44, 95% CI = 2.63 to 4.49), 1-3 years (aPR = 2.51, 95% CI = 2.13 to 2.95), and 4-6 years (aPR = 1.84, 95% CI = 1.49 to 2.26).

Conclusions: Daily e-cigarette use is strongly associated with recent smoking cessation (≤6 years) among US adults. Frequency of e-cigarette use and smoking cessation duration are important parameters when analyzing the effects of e-cigarettes in population surveys.

Implications: There is controversy on whether e-cigarettes promote or prevent smoking cessation. This study presents a detailed analysis of the association between e-cigarette use and smoking cessation in the United States considering frequency of e-cigarette use and duration of smoking cessation. The latter was considered appropriate because e-cigarette awareness and use were low in the United States before 2010. Daily e-cigarette use is strongly associated with recent (≤6 years) smoking cessation in the United States. Both frequency of e-cigarette use and duration of smoking cessation are important factors in determining the effects of e-cigarettes in population studies.