Do e-cigarettes help current smokers quit, or do they just become an additional nicotine habit? There have been few population-based studies of this question, and a new study of more than 30,000 adults in Sweden indicates that traditional smokers use both methods.
The study, published Friday in JAMA Open
, found that smokers who do both were also more likely to have respiratory symptoms. The researchers noted that e-cigarette use as a smoking cessation tool is not yet established. Their hypothesis was that use of e-cigarettes was most common among former smokers, since that is how e-cigarette companies market the devices.
The study was based on 2 random samples of the population in different sections of the country: the Obstructive Lung Disease in Northern Sweden (OLIN) study, with 6519 participants, and the West Sweden Asthma Study (WSAS), with 23,753 participants.
Participants were asked questions about respiratory symptoms
during the last 12 months: smoking habits, current e-cigarette use, and demographic characteristics. Respiratory symptoms were defined as sputum production, chronic productive cough, long-standing cough, any wheeze, and recurrent wheeze.
Of 30,272 participants, about 54% were female. The number of current smokers was 3694 (12.3%), and 7305 (24.4%) were former smokers.
The study found that the prevalence of e-cigarette use was 2%, and e-cigarette users were more likely to be male (odds ratio [OR], 1.35; 95% CI, 1.12-1.62). They were also more likely to have lower educational attainment: primary school (OR, 1.99; 95% CI, 1.51-2.64) versus upper secondary school (OR, 1.57; 95% CI, 1.25-1.96). E-cigeratte users were also vastly more likely to be current smokers (OR, 18.10; 95% CI, 14.19-23.09) than former smokers (OR, 2.37; 95% CI, 1.73-3.24).
E-cigarette use was also associated with being in a younger age group—20 to 29 years (OR, 2.77; 95% CI, 1.90-4.05), 30 to 39 years (OR, 2.27; 95% CI, 1.53-3.36), 40 to 49 years (OR, 1.65; 95% CI, 1.11-2.44), and 50 to 59 years (OR, 1.47; 95% CI, 1.01-2.12).
Among current smokers, 350 of 3566 (9.8%; 95% CI, 8.8%-10.8%) used e-cigarettes compared with 79 of 6875 (1.1%; 95% CI, 0.9%-1.3%) in former smokers and 96 of 15 832 (0.6%; 95% CI, 0.5%-0.7%) in nonsmokers (P
Among e-cigarette users who answered the survey question about cigarette-smoking habits (n = 525), 350 (66.7%; 95% CI, 62.7%-70.7%) were current smokers, 79 (15%; 95% CI, 11.9%-18.1%) were former smokers, and 96 (18.3%; 95% CI, 15%-21.6%) were nonsmokers (P
<.001 for trend).
Those who used both e-cigarettes and conventional cigarettes had the highest prevalence of respiratory symptoms. In addition, respiratory symptoms were generally more common among e-cigarette users among both former smokers and nonsmokers. E-cigarette use was also associated with smoking a higher number of conventional cigarettes per day.
While e-cigarettes did not seem to serve as a method to quit smoking, the researchers had several explanations for their results. It’s possible that the group included smokers who do want to quit and have just started using e-cigarettes, thus becoming dual smokers. Also, some smokers start using e-cigarettes in places where they cannot smoke conventional cigarettes, such as in certain public situations
Another possibility is that e-cigarettes simply do not work as a tool to help people quit smoking, and the authors noted that the efficacy of e-cigarettes as a smoking cessation tool is still under debate.
One limitation of this study, they wrote, is that it was based on survey response rates, which may have caused selection bias and a lack of representativeness.
The long-term health effects of e-cigarettes is still unknown, and more studies are needed, the authors concluded.
Hedman L, Backman H, Stridsman C, et al. Association of electronic cigarette use with smoking habits, demographic factors, and respiratory symptoms. JAMA Netw Open
. 2018;1(3):e180789. doi: 10.1001/jamanetworkopen.2018.0789