Association of Cigarette-E-Cigarette Transitions With Respiratory Symptom Resolution.

Introduction: Adults increasingly use e-cigarettes for cigarette cessation because of the perceived reduced risk. While e-cigarette use is associated with reduced toxicant exposure compared with smoking, it is unclear whether transitioning from cigarettes to e-cigarettes is associated with resolution of respiratory symptoms.

Methods: Data were obtained from the Population Assessment of Tobacco and Health (PATH) study waves 1-5. US adult participants were separated into observations with cigarette-e-cigarette exposure intervals determined from PATH waves 1-2, 2-3, and 3-4. Observations were included if the participant reported exclusively smoking at baseline and reported a baseline cough or wheeze. Mixed-effect Poisson models measured the association between cigarette-e-cigarette transitions over the two-wave exposure interval (from smoking to nonuse, exclusive e-cigarette use, continued smoking, or dual use) and the reported resolution of the participant's cough or wheeze.

Results: Among 5210 (3362 unique) observations, transitioning from cigarettes to e-cigarettes was associated with increased rates of wheeze resolution (incidence rate ratio [IRR] = 1.33; 95% confidence interval [CI] = 1.01 to 1.75) but not cough resolution (IRR = 1.18; 95% CI = 0.93 to 1.50) compared with persistent smoking. Cigarette to dual-use transitions were not associated with improvements in symptom resolution, and those who switched to dual use and maintained or increased their smoking intensity had 15% decreased rates of respiratory symptom resolution compared with persistent smoking.

Discussion: E-cigarette-assisted smoking cessation may increase rates of respiratory symptoms resolution among smokers who completely transition to e-cigarettes; however, there is risk for additional harm among those who initiate e-cigarette use without decreasing their smoking intensity.

Implications: Government agencies are increasingly weighing the risks and benefits of e-cigarette-assisted cigarette cessation given the reduced harm associated with e-cigarette use. This study provides novel evidence that completely transitioning from cigarettes to e-cigarettes is associated with increased rates of resolution from self-reported wheeze symptoms. However, risk exists in e-cigarette-assisted cigarette cessation, as those who transitioned from exclusive cigarette smoking to dual use and did not reduce their cigarette smoking intensity had decreased rates of respiratory symptom resolution compared with persistent smokers.