according to recent longitudinal analysis published in the .
E-cigarettes have been promoted as a safer alternative to combustible tobacco, and until recently, there has been little and conflicting evidence by which to test this hypothesis. This study conducted by Dharma N. Bhatta, PhD, and Stanton A. Glantz, PhD, of the Center for Tobacco Control Research and Education at the University of California, San Francisco, is one of the first longitudinal examinations of e-cigarette use and controlling for combustible tobacco use.
Dr. Bhatta and Dr. Glantz performed a multivariable, logistic regression analysis of adults enrolled in the nationally representative, population-based, longitudinal Population Assessment of Tobacco and Health study. The researchers analyzed the tobacco use of adults in the study in three waves, following them through wave 1 (September 2013 to December 2014), wave 2 (October 2014 to October 2015), and wave 3 (October 2015 to October 2016), analyzing the data between 2018 and 2019. Overall, wave 1 began with 32,320 participants, and 15.1% of adults reported respiratory disease at baseline.
Lung or respiratory disease was assessed by asking participants whether they had been told by a health professional that they had chronic obstructive pulmonary disease, chronic bronchitis, emphysema, or asthma. The researchers defined e-cigarette and combustible tobacco use as participants who never, currently, or formerly used e-cigarettes or smoked combustible tobacco. Participants who indicated they used e-cigarettes or combustible tobacco frequently or infrequently were placed in the current-user group, while past users were those participants who said they used to, but no longer use e-cigarettes or combustible tobacco.
The results showed former e-cigarette use (adjusted odds ratio, 1.34; 95% confidence interval, 1.23-1.46) and current e-cigarette use (aOR, 1.32; 95% CI, 1.17-1.49) were associated with an increased risk of having incident respiratory disease.
The data showed a not unexpected statistically significant association between former combustible tobacco use (aOR, 1.29; 95% CI, 1.14-1.47) as well as current combustible tobacco use (aOR, 1.61; 95% CI, 1.42-1.82) and incident respiratory disease risk.
There was a statistically significant association between respiratory disease and former or current e-cigarette use for adults who did not have respiratory disease at baseline, after adjusting for factors such as current combustible tobacco use, clinical variables, and demographic differences. Participants in wave 1 who reported former (aOR, 1.31; 95% CI, 1.07-1.60) or current e-cigarette use (aOR, 1.29; 95% CI, 1.03-1.61) had a significantly higher risk of developing incident respiratory disease in subsequent waves. There was also a statistically significant association between use of combustible tobacco and subsequent respiratory disease in later waves of the study (aOR, 2.56; 95% CI, 1.92-3.41), which the researchers noted was independent of the usual risks associated with combustible tobacco.
The investigators also looked at the link between dual use of e-cigarettes and combustible tobacco and respiratory disease risk. “The much more common pattern is dual use, in which an e-cigarette user continues to smoke combusted tobacco products at the same time (93.7% of e-cigarette users at wave 2 and 91.2% at wave 3 also used combustible tobacco; 73.3% of e-cigarette users at wave 2 and 64.9% at wave 3 also smoked cigarettes),” they wrote.
The odds of developing respiratory disease for participants who used both e-cigarettes and combustible tobacco were 3.30, compared with a participant who never used e-cigarettes, with similar results seen when comparing e-cigarettes and cigarettes.
“Although switching from combustible tobacco, including cigarettes, to e-cigarettes theoretically could reduce the risk of developing respiratory disease, current evidence indicates a high prevalence of dual use, which is associated with in-creased risk beyond combustible tobacco use,” the investigators wrote.
Harold J. Farber, MD, FCCP, professor of pediatrics in the pulmonary section at Baylor College of Medicine and Texas Children’s Hospital, both in Houston, said in an interview that the increased respiratory risk among dual users, who are likely using e-cigarettes and combustible tobacco together as a way to quit smoking, is particularly concerning.
“There is substantial reason to be concerned about efficacy of electronic cigarette products. Real-world observational studies have shown that, on average, tobacco smokers who use electronic cigarettes are less likely to stop smoking than those who do not use electronic cigarettes,” he said. “People who have stopped tobacco smoking but use electronic cigarettes are more likely to relapse to tobacco smoking than those who do not use electronic cigarettes.”
Dr. Farber noted that there are other Food and Drug Administration–approved medications for treating tobacco addiction. In addition, the World Health Organization, American Medical Association, Centers for Disease Control and Prevention, and FDA have all advised that e-cigarettes should not be used as smoking cessation aids, he said, especially in light of current outbreak of life-threatening e-cigarette and vaping lung injuries currently being investigated by the CDC and FDA.
“These study results suggest that the CDC reports of e-cigarette, or vaping, product use–associated lung injury are likely to be just the tip of the iceberg,” he said. “Although the CDC has identified vitamin E acetate–containing products as an important culprit, it is unlikely to be the only one. There are many substances in the emissions of e-cigarettes that have known irritant and/or toxic effects on the airways.”
Dr. Bhatta and Dr. Glantz acknowledged several limitations in their analysis, including the possibility of recall bias, not distinguishing between nondaily and daily e-cigarette or combustible tobacco use, and combining respiratory conditions together to achieve adequate power. The study shows an association, but the mechanism by which e-cigarettes may contribute to the development of lung disease remains under investigation.
This study was supported by grants from the National Institute on Drug Abuse; the National Cancer Institute; the FDA Center for Tobacco Products; the National Heart, Lung, and Blood Institute; and the University of California, San Francisco Helen Diller Family Comprehensive Cancer Center Global Cancer Program. Dr. Bhatta and Dr. Glantz reported no relevant conflicts of interest.
SOURCE: Bhatta DN, Glantz SA. Am J Prev Med. 2019 Dec 16. doi: 10.1016/j.amepre.2019.07.028.