Smoking traditional cigarettes in addition to using e-cigarettes results in harmful health effects similar to smoking cigarettes exclusively, according to new research published today in the American Heart Association’s flagship journal Circulation.
Smoking, a well-known link to cardiovascular disease and death, appears to be on the decline.
In a large data analysis of more than 7,100 U.S. adults ages 18 and older, researchers studied the association of cigarette smoking and e-cigarette use with inflammation and oxidative stress as biomarkers. Inflammation and oxidative stress are key contributors to smoking-induced cardiovascular disease and their biomarkers have been shown to be predictors of cardiovascular events, including heart attack and heart failure.
“This study is among the first to use nationally representative data to examine the association of cigarette and e-cigarette use behaviors with biomarkers of inflammation and oxidative stress,” said Andrew C. Stokes, Ph.D., assistant professor of global health at Boston University School of Public Health in Boston and first author of the study.
“Given the lag time between tobacco exposure and disease symptoms and diagnosis, identifying the association between e-cigarette use and sensitive biomarkers of subclinical cardiovascular injury is necessary for understanding the long-term effects of newer tobacco products such as e-cigarettes.”
Researchers used data from the Population Assessment of Tobacco and Health (PATH) Study, a nationally representative longitudinal cohort in the U.S. This study’s analysis was restricted to adults 18 years and older from Wave 1 of the survey, which was administered from 2013 to 2014 and included the collection of blood and urine samples.
Five biomarkers of inflammation and oxidative stress were analyzed. Participants were slotted into four categories based on the use of traditional cigarettes and e-cigarettes within a 30-day period: nonuse of cigarettes and e-cigarettes; exclusive vaping; exclusive cigarette smoking; and dual use of cigarettes and e-cigarettes.
To test the robustness of initial results, the scientists repeated the analyses in subgroups of respondents, including those with no past 30-day use of any other tobacco products.
Of the study participants, more than half (58.6%) did not use cigarettes or e-cigarettes; nearly 2% vaped exclusively; about 30% smoked cigarettes exclusively; and about 10% used e-cigarettes and traditional cigarettes.
The analysis found:
- Participants who vaped exclusively showed a similar inflammatory and oxidative stress profile as people who did not smoke cigarettes or use e-cigarettes.
- Participants who smoked exclusively and those who used cigarettes and e-cigarettes had higher levels across all biomarkers assessed compared to participants who did not use cigarettes or e-cigarettes.
- Compared to participants who smoked exclusively, those who vaped exclusively had significantly lower levels of almost all inflammatory and oxidative stress biomarkers. However, participants who used cigarettes and e-cigarettes had levels of all inflammatory and oxidative stress biomarkers comparable to those who smoked exclusively.
“This study adds to the limited body of research we have on biologic measures in those using e-cigarettes,” said study co-author Rose Marie Robertson, M.D., FAHA, deputy chief science and medical officer of the American Heart Association and co-director of the Association’s National Institutes of Health/Food and Drug Administration-funded Tobacco Center of Regulatory Science, which supported the study.
“I believe it has an important message for individuals who may believe using e-cigarettes while continuing to smoke some combustible cigarettes reduces their risk. This commonly-seen pattern of dual use was not associated with lower levels of inflammatory markers, and thus is not likely to offer a reduction in risk in this specific area.”
Researchers also conducted extensive analyses to test the results against the influence of related behaviors such as the use of other tobacco products and marijuana, and secondhand smoke exposure. The results remained consistent across the additional analyses.
The large population sample of this study makes the findings applicable to the U.S. adult population. One of the study’s limitations is its cross-sectional approach of looking at population data at one point in time, which makes it impossible to establish causality.
Researchers said the study highlights the importance of continued public education regarding the risks of cigarette smoking and the failure of dual use to reduce risk.
“The results could be used to counsel patients about the potential risk of using both cigarettes and e-cigarettes,” Stokes said. “Some people who smoke cigarettes, pick up e-cigarette use to reduce the frequency with which they smoke cigarettes. They often become dual users of both products rather than switching entirely from one to the other. If e-cigarettes are used as a means to quit smoking, cigarette smoking should be completely replaced and a plan to ultimately attain freedom from all tobacco products should be advised.”
E-cigarettes are promoted as healthier alternatives to conventional cigarettes. Many cigarette smokers use both products. It is unknown whether the additional use of e-cigarettes among cigarette smokers (dual users) is associated with reduced exposure to tobacco-related health risks.
Cross-sectional analysis was performed using baseline data from the Health eHeart Study, among English-speaking adults, mostly from the United States. Cigarette use (# cigarettes/day) and/or e-cigarette use (# days, # cartridges, and # puffs) were compared between cigarette only users vs. dual users.
Additionally, we examined cardiopulmonary symptoms/ conditions across product use: no product (neither), e-cigarettes only, cigarettes only, and dual use. Among 39,747 participants, 573 (1.4%) reported e-cigarette only use, 1,693 (4.3%) reported cigarette only use, and 514 (1.3%) dual use.
Dual users, compared to cigarette only users, reported a greater median (IQR) number of cigarettes per day, 10.0 (4.0–20.0) vs. 9.0 (3.0–15.0) (p < .0001), a lower (worse) median (IQR) SF-12 general health score, 3.3 (2.8–3.8) vs. 3.5 (2.8–3.9) (p = .0014), and a higher (worse) median (IQR) breathing difficulty score in the past month, 2.0 (1.0–2.0) vs. 1.0 (1.0–2.0) (p = .001).
Of the 19 cardiopulmonary symptoms/ conditions, having a history of arrhythmia was significantly different between cigarette only users (14.2%) and dual users (17.8%) (p = .02). In this sample, dual use was not associated with reduced exposure to either (i) cigarettes, compared to cigarette only users or (ii) e-cigarettes, compared to e-cigarette only users.
E-cigarette only use, compared to no product use, was associated with lower general health scores, higher breathing difficulty scores (typically and past month), and greater proportions of those who responded ‘yes’ to having chest pain, palpitations, coronary heart disease, arrhythmia, COPD, and asthma.
These data suggest the added use of e-cigarettes alone may have contributed to cardiopulmonary health risks particularly respiratory health risks.
Dual use and cigarette/e-cigarette exposure
In the present study, even with the use of e-cigarettes, dual users did not smoke fewer cigarettes than those who smoked only cigarettes. It may be possible that the added nicotine from e-cigarettes did not satisfy dual users’ nicotine levels enough to reduce their usual cigarette intake.
Studies have shown that e-cigarettes deliver lower levels of plasma nicotine than conventional cigarettes [20, 21], although more experienced e-cigarette users can also adjust their devices and e-liquid nicotine concentrations to achieve their desired nicotine levels [19, 22].
In the Health eHeart Study sample, there were no detectable differences in e-cigarette use dose, as measured by number of days, cartridges/ refills, and puffs per day, between those who reported using e-cigarettes only and dual users. Overall, dual users had greater exposure to toxicants from using both cigarettes and e-cigarettes.
This finding is consistent with a study by Shahab et al. (2017), where exposure to carcinogens and toxins was not substantially reduced in dual users compared to those who smoked only cigarettes [34].
In the Health eHeart Study sample, one fifth of e-cigarette users reported never smoking cigarettes, whereas the remaining majority of e-cigarette users were former cigarette smokers. This is consistent with a study by Zhu et al. (2017), which reported a significant association between a substantial increase in e-cigarette use among cigarette smokers and smoking cessation rates at the US population level [35].
These data suggest that some cigarette users, perhaps those with lower nicotine dependence, might have successfully quit smoking cigarettes with the aid of e-cigarettes. However, dual use was not associated with reduced risk of tobacco exposure compared to smoking cigarettes alone. Further, the added exposure to e-cigarette toxicants, including more nicotine, might have adverse health outcomes.
Dual use, nicotine dependence, and health
Dual users are exposed to toxicants from cigarette smoke, e-cigarette vapor, and nicotine from both products. In the Health eHeart study, dual users were more likely to report lower general health scores and greater breathing difficulty. The health risks of first- and secondhand cigarette smoke exposure are well-established [1], and the evidence for e-cigarettes on pulmonary and cardiovascular health risks is growing.
In the present study, compared to those who did not use either e-cigarettes or cigarettes, participants who reported e-cigarette use alone were more likely to report both short-term and long-term pulmonary symptoms and conditions, including breathing difficulty, asthma, and COPD. Compared to those who used e-cigarettes alone, participants who reported dual use had even greater risk of breathing difficulty, asthma, and COPD.
These findings support other studies to suggest that e-cigarettes may have adverse health effects on the respiratory system. Previous studies have reported e-cigarette vapor contain aerosols and other particles, including propylene glycol, that are associated with increased risk of airway irritation and resistance [36–39].
Studies from animal and basic science models have consistently shown specific e-cigarette liquid flavorings contain respiratory toxins [40–43]. Compared to those who reported neither e-cigarette or cigarette use, those who reported e-cigarette only use were more likely to report chest pain, palpitations, coronary artery disease, and an arrhythmia, which supports findings from other studies where e-cigarette use was associated with cardiac conditions such as arrhythmias and hypertension [44]. These conditions may be attributed to the increased exposure to nicotine (from e-cigarettes), which itself is associated with acute cardiovascular events and accelerated atherogenesis [45, 46].
These study findings provide early epidemiologic evidence to suggest that dual users are at higher risk of breathing difficulty and arrhythmias, and that this increased risk is likely attributable to e-cigarette use or the potential combined effect of cigarette and e-cigarette use.
More studies are needed to elucidate the relationship between dual use and both short- and long-term health outcomes. In the meantime, we recommend dual users treat e-cigarettes (at the very least) like other nicotine replacement pharmacotherapies and recognize the potential for increased nicotine exposure.
There is also the added risk of exposure to e-cigarette toxicants and the potential synergistic effect of dual use on health. Therefore, dual users are encouraged to stop smoking cigarettes and e-cigarettes to minimize tobacco and e-cigarette-related health risks.
reference link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6059385/
Co-authors are Wubin Xie, Dr.P.H., M.P.H.; Anna Wilson, M.P.H.; Hanqi Yang, B.A.; Olusola Orimoloye, Ph.D.; Alyssa Harlow, M.P.H.; Jessica Fetterman, Ph.D.; Andrew DeFilippis, Ph.D.; Emelia Benjamin, M.D., Sc.M.; Aruni Bhatnagar, Ph.D.; Naomi Hamburg, M.D., M.Sc.; and Michael Blaha, M.D., M.P.H. The authors’ disclosures are in the manuscript.
Funding: The National Heart, Lung, and Blood Institute of the National Institutes of Health funded the study through grants to the American Heart Association’s Tobacco Center of Regulatory Science which works closely with investigators at institutions across the country to pursue research that adds to the existing knowledge about the health impacts of smoking and nicotine-related products, findings that can help inform regulation of tobacco products.
Source:American Heart Association
