THURSDAY, Jan. 14, 2016 (HealthDay News) -- Electronic cigarettes are promoted as a way to help smokers kick the habit, but a new study contends that the devices hamper rather than help.
E-cigarette use actually lowers smokers' chances that they'll quit tobacco by about 28 percent, according to an evidence review published online Jan. 14 in The Lancet Respiratory Medicine journal.
"We found that e-cigarette use was associated with significantly less quitting," said study senior author Stanton Glantz, a professor with the University of California, San Francisco's Center for Tobacco Control Research and Education. "E-cigarettes are being promoted as a means of quitting, but they're actually having the opposite effect."
Electronic cigarettes are battery-powered devices that heat nicotine and flavorings to create a vapor that is inhaled by the user.
The e-cigarette industry and "vaping" advocates have argued that the devices are a healthier alternative to traditional tobacco cigarettes, since users aren't inhaling carcinogenic smoke. They've also claimed that smokers could use e-cigs to wean themselves off tobacco.
These claims have been met with some opposition by the medical community. For example, in 2015 the U.S. Preventive Services Task Force concluded there was insufficient evidence to recommend the devices to help adults quit smoking, the study authors pointed out in background notes.
To see whether the latest research on e-cigarettes supports industry claims, Glantz's team reviewed 38 studies assessing the association between e-cigarette use and cigarette cessation among adult smokers.
"We looked at every single paper out there we could find," he said. "We did not do any cherry-picking at all."
The study authors then combined the results of 20 studies that had control groups of smokers not using e-cigarettes, comparing them to smokers who also use e-cigarettes to see which group quit tobacco more often.
The researchers concluded that the odds of quitting smoking were 28 percent lower in smokers who used e-cigarettes compared to those who did not. The finding held up even after the researchers compensated for differences in study participants, the strength of smokers' nicotine dependence, the design of the studies and definitions of e-cigarette use, Glantz said.
The new evidence review has met with some criticism.
Ann McNeill, a professor of tobacco addiction at King's College London, in England, criticized the review and said the findings should be dismissed.
McNeill said it was a mistake to include two papers she co-authored into the evidence review, because both papers may have excluded people who already had successfully quit smoking with help from e-cigarettes.
"I am concerned at the huge damage this publication may have," McNeill said in a statement. "Many more smokers may continue smoking and die if they take from this piece of work that all evidence suggests e-cigarettes do not help you quit smoking. That is not the case."
Glantz said he was aware of the issues raised by McNeill, and factored them into the study's conclusions. The issues did not affect the results, he said.
Dr. Norman Edelman, senior scientific advisor to the American Lung Association, said e-cigarettes likely interfere with efforts to quit smoking by keeping users hooked on nicotine.
"It tells us simply switching from one nicotine delivery system to another nicotine delivery system doesn't lead to quitting the first nicotine delivery system," Edelman said of the new findings. "People will not naturally give up cigarettes, even though in most venues e-cigarettes are cheaper and people consider e-cigarettes to be safer."
E-cigarettes also help to keep smokers hooked by allowing them to "vape" nicotine while indoors, in places where clean air laws forbid smoking, said Cliff Douglas, director of the American Cancer Society's Tobacco Control Center.
"They're promoted as a means of bridging those times where one can't smoke a traditional cigarette," Douglas said. "That's the opposite of cessation. That's encouraging ongoing addiction."
Edelman and Douglas said the new study shows why the U.S. Food and Drug Administration needs to step in and begin regulating e-cigarettes as soon as possible.
The FDA issued a proposed rule in 2014 that would allow the agency to regulate e-cigarettes in the same way as other tobacco products, but the agency has not yet placed that rule into effect.
"The American Lung Association has been saying for over a year that the FDA ought to go ahead and regulate these devices," Edelman said. "Once they did that, the companies could not make any claims without approval."
Glantz believes the FDA could take action even without its proposed new rules. Prior legal decisions have found that "if the companies make any therapeutic claim -- and helping to quit smoking is a therapeutic claim -- then the FDA could regulate them under current rules," he said.
"This shows me the FDA today needs to clamp down on e-cigarette companies' claims that these things help people quit smoking," Glantz said. "Not only is that misleading people, it's actually hurting them by reducing the odds that people who are current smokers will quit."
For more on e-cigarettes, visit the U.S. Department of Health and Human Services.