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Since the arrival of e-cigarettes, debates have raged in public health and research circles about their value and risks. Can they actually help people stop smoking for good? How much harm can they cause? How does that harm compare to the harm from smoking tobacco cigarettes? Do e-cigarettes increase the risk that kids will start smoking? A cherry-picker could find studies to support any position on any of these questions, but it takes time for enough researchers to conduct enough high-quality studies that a consensus can emerge. On the first question — can e-cigarettes help some people quit smoking — that consensus is increasingly pointing to “Yes.”
But — as with so much in health and behavior research — it depends. A new study whose methods are more granular than in past studies has started to tease out what makes the difference and who is most likely to benefit. The basic finding: the more days you use e-cigarettes, the more likely you are to successfully quit.
“Results revealed that greater frequency of e-cigarette use beyond ever use [using one at least once] and especially with 20 or more days of use in the past month was strongly associated with both having made a quit attempt and a greater likelihood of three months or more of cigarette smoking cessation,” wrote David T. Levy, PhD, and his colleagues at the Georgetown University Lombardi Comprehensive Cancer Center. “The consistency of positive associations with quit attempts or cessation success suggests that more frequent e-cigarette use may be effective as a smoking cessation aid.”
These results supported the findings of another recent study in BMJ that assessed e-cigarette and tobacco smoking rates across the US population over five years.
The research, funded by the National Institute of Drug Abuse and the National Cancer Institute (no industry!), was published today in the journal Nicotine & Tobacco Research. By no means will this study put to rest the debate between those who say e-cigarettes can’t be a cessation tool and those who say it can (including thousands of people on Twitter who will tell you in a heartbeat, multiple times, that it helped them). But one of its most important contributions is providing a template for how to study this question in a more detailed way than past observational studies.
“An important part of our study was to distinguish the effect of e-cigarette use on quit attempts and quit success by separating considering the smokers who might attempt to quit and those that have actually made a quit attempt,” the authors wrote.
The researchers used the same data source as the BMJ study and even past studies finding less evidence for e-cigarettes as smoking cessation tools, the Tobacco Use Supplement survey used in the annual Current Population Survey conducted by the Census Bureau. This survey asks detailed questions about smokers’ habits, quit attempts and quit success.
The data for this study came from the 2014-2015 survey and included 23,633 smokers, just under half of whom (10,973) had attempted at least once to quit smoking. Most of those who tried to quit didn’t succeed, a total of 8,419 people. But 1,596 people had remained successful for at least 3 to 12 months, 623 of them had quit one to three months before the survey, and 335 had just quit within the past month. By analyzing survey responses in these individual groups about who had used e-cigarettes and how often, the researchers were able to analyze the link between e-cigarettes and quitting more closely.
They found that smokers who used an e-cigarette only once or a few times were less likely to successfully quit, a possible reason for some past studies’ findings that e-cigarettes didn’t help if those studies lumped together people who had ever tried an e-cigarette and those who used them more frequently. But for those who used e-cigarettes more often, especially the longer they used them, the success rate went up. Each additional day of e-cigarette used increased the odds of successfully quitting by about 5%, the researchers found. Using e-cigarettes for at least five days in a month increased the odds of quitting by 59%, and using them at least 20 days more than doubled the odds.
These calculations also took into account other factors that could have influenced people’s success rates, including the average price of cigarettes in their state, laws in their state related to smoking, use of smokeless tobacco, how often they smoked, gender, age (broken down into very small groups), race/ethnicity, income, educational level, marital status, employment status and living in a rural or urban area. The others suggested that a study in 2010 using the same data source might have found e-cigarettes less helpful at helping people quit because e-cigarettes were not as sophisticated as they are today, especially in delivering bigger doses of nicotine.
As with any research question, it will require many more studies to parse out who e-cigarettes can help quit smoking and the best way to use them, and too little information exists about long-term potential for harm from e-cigarettes. But all the evidence to date suggests that e-cigarettes are not nearly as harmful and life-threatening as tobacco use, so e-cigarettes appear to be a viable quitting option, the researchers note, for those who don’t succeed with other methods.