At the halfway point in a 24-week trial, participants who got counseling with e-cigarettes containing nicotine had substantially higher abstinence rates than those who received counseling alone, but the difference diminished by week 24, researchers report in JAMA.
Surprisingly, participants who got counseling plus nicotine-free e-cigarettes didn't differ from those getting counseling alone at 12 weeks, but by week 24 they had superior abstinence rates.
"It's likely that participants receiving e-cigarettes with nicotine displaced their dependence from conventional cigarettes while they were receiving e-cigarettes," said lead study author Dr. Mark Eisenberg of the divisions of Cardiology and Clinical Epidemiology at Jewish General Hospital/McGill University in Montreal.
"After 12 weeks, when they were no longer receiving e-cigarettes, their nicotine dependence likely brought some smokers back to smoking conventional cigarettes," Dr. Eisenberg said by email.
In the trial, researchers randomly assigned current smokers to one of three treatment groups for 12 weeks: counseling alone (n=121), counseling combined with nicotine-free e-cigarettes (n=127), or counseling with e-cigarettes containing nicotine (n=128).
At 12 weeks, point prevalence abstinence based on 7-day recall and results from expired carbon monoxide tests was 21.9% for the group that received counseling and e-cigarettes with nicotine, compared with 9.1% for those that received only counseling. By 24 weeks, however, there was no statistically significant difference in abstinence between these two groups (17.2% vs 9.9%).
The picture looked different for nicotine-free e-cigarettes. At 12 weeks, there was no statically significant difference in point prevalence-based abstinence between counseling plus e-cigarettes and counseling alone (17.3% vs 9.1%). But at 24 weeks, significantly more participants achieved abstinence with counseling plus e-cigarettes than with counseling alone (20.5% vs 9.9%).
When the study began, participants had been smoking a mean of 21 cigarettes a day for a mean of 35 years. The majority (91%) had tried to quit at least once before, and most had tried smoking cessation medications or behavioral therapy (80%).
At 12 weeks, people who received counseling and e-cigarettes with nicotine smoked a mean of 12.6 fewer daily cigarettes than at baseline, and people who had counseling and nicotine-free e-cigarettes smoked a mean of 10.6 fewer daily cigarettes. This compared with a mean reduction of 7.0 daily cigarettes with counseling alone.
Participants self-reported prior-week abstinence at 12 and 24 weeks. Among those who did report abstinence, this was biochemically validated in 53 of 61 people (87%) at 12 weeks, and in 46 of 60 (77%) at 24 weeks.
Overall, 94% of participants with nicotine-containing e-cigarettes and 93% of participants with nicotine-free e-cigarettes experienced mild adverse events. Most often, these events included cough, dry mouth, headache, rhinitis, and throat irritation.
A total of seven serious adverse events occurred, five of which happened with e-cigarettes. One person who received e-cigarettes with nicotine was hospitalized with chronic obstructive pulmonary disease exacerbation secondary to pneumonia. One participant on nicotine-free e-cigarettes and one participant who received counseling alone had a myocardial infarction.
One limitation of the study was the unexpected early termination after recruitment of 77% of the intended sample size, the study team notes. It's possible that with a larger sample size that the study would have found clear and statically significant differences in cessation rates with and without e-cigarettes.
"The evidence that e-cigarettes can help smokers to stop smoking is getting stronger, though more is still needed," said Dr. Nancy Rigotti, a professor at Harvard Medical School and director of the Tobacco Research and Treatment Center at Massachusetts General Hospital in Boston.
While e-cigarettes are not harmless, they are far less harmful than continuing to smoke cigarettes, Dr. Rigotti, author of an editorial accompanying the study, said by email.
"Smokers who have not been able to quit smoking with conventional medications or treatments should consider - and discuss with their doctors - the risks and benefits of using e-cigarettes to stop smoking cigarettes," Dr. Rigotti advised. "Smokers who do try e-cigarettes should be sure to switch completely to have the best chance of success in quitting smoking."
By Lisa Rapaport
SOURCE: https://bit.ly/3lkcHUV and https://bit.ly/3kmmFUi JAMA, online November 10, 2020.
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