Jonathan Berlowitz and colleagues’ new paper Cigarette‒E-cigarette Transitions and Respiratory Symptom Development adds to the already strong case that e-cigarette use increases the risk of respiratory symptoms and that dual use (using e-cigarettes while smoking cigarettes) is more dangerous than using either product alone. Most important, switching from cigarettes only to e-cigarettes only did not significantly reduce risk.
They used several years of adult data collected in the FDA/NIH PATH study to examine how the risks of cough and wheezing changed when tobacco consumption behavior changed from year-to-year. The divided respondents into nonusers of either product, e-cigarette users, smokers and dual users and computed how disease risk changed when product use changed, controlling for history of smoking (pack years), other tobacco use, and demographic variables.
They found that nonusers who started using e-cigarettes use substantially increased risk of wheeze (incident rate ratio=1.62; 95% CI 1.12-2.34). There were not significant changes is risk of wheeze for people who switched from cigarettes to e-cigarettes (incident rate ratio=0.87; 95% CI 0.52-1.46), suggesting no benefit of switching.
Going from nonuse to dual use more than doubled risk of wheeze (incident rate ratio=2.62; 95% CI 1.79-3.85), whereas transitioning from dual use nonuse of either product or to e-cigarettes only (i.e., dropping cigarettes) were followed by with large reductions in wheezing (incident rate ratio=0.43; 95% CI 0.22-0.84 and 0.36; 95% CI 0.20, 0.63, respectively).
The dual use findings are particularly important because 59% of e-cigarette users are dual users, i.e., most adult e-cigarette users in their study did not “switch completely,” the behavior e-cigarette advocates and the FDA assume. Even among those who did switch completely there was no wheezing benefit.
Except for transitioning from nonuse to e-cigarettes, the results for dry nighttime cough were similar, although some of the changes did not reach statistical significance.
This carefully done study also provides evidence against claims that the observed associations between e-cigarette use and respiratory disease are simply artifacts of past smoking.
Here is the abstract:
Introduction: E-cigarette use is associated with pulmonary inflammation, functional respiratory changes, and chronic lung disease. Most population-level E-cigarette research has utilized point-in-time measures of E-cigarette exposures, which may not generalize to adults who transition between cigarettes and E-cigarettes.
Methods: Data obtained from the Population Assessment of Tobacco and Health study were collected from 2013 to 2019 and analyzed in 2022. Three observations were created per respondent, with exposure intervals assessed over Waves 1-2, 2-3, and 3-4. Each wave of the exposure interval was classified as nonuse, exclusive E-cigarette use, exclusive smoking, or dual use, producing 16 possible cigarette‒E-cigarette transitions. The association between transitions and both dry nighttime cough and wheeze symptom development during follow-up were assessed using mixed-effects Poisson models.
Results: Among 33,231 observations from 13,528 unique participants, transitioning from nonuse to exclusive E-cigarette use was associated with 1.62 times higher incidence rate of wheeze (incident rate ratio=1.62; 95% CI=1.12, 2.34) than persistent nonuse. There was no change in reported dry nighttime cough (incident rate ratio=0.84; 95% CI=0.52, 1.35) or wheeze (incident rate ratio=0.87; 95% CI=0.52, 1.46) in individuals who switched from cigarettes to E-cigarettes, whereas transitioning from dual use to E-cigarette use was associated with large reductions in both symptoms (incident rate ratio=0.58; 95% CI=0.39, 0.87 and incident rate ratio=0.36; 95% CI=0.20, 0.63, respectively).
Conclusions: E-cigarette initiation among nonusers is associated with increased respiratory morbidity. Further research should assess the risks and benefits of E-cigarette‒assisted cigarette cessation given the reduction in symptom development rates among dual use to E-cigarette switchers.
The full citation is: Berlowitz JB, Xie W, Harlow AF, Blaha MJ, Bhatnagar A, Benjamin EJ, Stokes AC. Cigarette‒E-cigarette Transitions and Respiratory Symptom Development. Am J Prev Med. 2023 Apr;64(4):556-560. doi: 10.1016/j.amepre.2022.10.006. Epub 2022 Dec 5. PMID: 36470837; PMCID: PMC10033326. It is available here.