A new study, based on data from a large survey of current and former smokers in the United States, provides some of the strongest evidence yet that electronic cigarettes are helping Americans move from the first group to the second. The study, reported this month in the BMJ, finds that quit attempt and smoking cessation rates both increased significantly during the period when e-cigarette sales took off. Furthermore, these changes were entirely attributable to increased quitting among e-cigarette users, who were more likely to try and more likely to succeed than smokers who did not vape.
The researchers, led by University of California at San Diego public health professor Shu-Hong Zhu, found that 45.9 percent of smokers reported quit attempts in the 2014-15 Current Population Survey, up from 41.4 percent in 2010-11. The percentage who stopped smoking for at least three months also rose, from 4.5 percent to 5.6 percent. "This is the first time in almost a quarter of a century that the smoking cessation rate in the US has increased at the population level," Zhu and his colleagues write. "The 1.1 percentage point increase in cessation rate…might appear small, but it represents approximately 350?000 additional US smokers who quit in 2014-15."
What happened during this period that might account for the change? Zhu et al. note that e-cigarette use in the U.S. "became noticeable around 2010 and increased dramatically by 2014."
That correlation is reinforced by the researchers' subgroup analysis of the 2014-15 data, which found that 65 percent of smokers who had used e-cigarettes in the previous year had tried quitting, compared to 40 percent of the other smokers. "Numerically speaking," the authors say, "it was this e-cigarette user subgroup that raised the overall quit attempt rate for 2014-15, and thus the rate was statistically significantly higher than in all previous survey years."
Vapers also had a higher cessation rate than nonvapers in 2014-15: 8.2 percent vs. 4.8 percent. "Again," Zhu et al. write, "the 2014-15 survey had a noticeably higher overall cessation rate because the e-cigarette user subgroup had a higher cessation rate than those who did not report e-cigarette use in the past year."
Since this is an observational study rather than a randomized, controlled experiment, alternative explanations are possible. But the researchers persuasively argue that neither the 2009 increase in the federal tobacco tax nor the TIPS From Former Smokers ad campaign that began in 2012 can adequately explain the increase in smoking cessation, especially in light of the stark subgroup differences. The impact of the tax hike was relatively small and short-lived, Zhu et al. say, while it is hard to see why the anti-smoking ads would have had an impact only on smokers "who happened to use e-cigarettes in 2014-15."
Still, smokers who try vaping may differ from those who do not in ways that make them more likely to quit. "Given that the e-cigarette user subgroup was the only group that had statistically significantly higher rates in 2014-15," Zhu et al. say, "it is tempting to attribute the increase in the overall smoking cessation rate in 2014-15 solely to e-cigarette use. However, e-cigarette use itself could be an indicator of motivation to quit smoking, which would predict a higher quit rate. Thus, attributing the full 73% relative difference to e-cigarettes is likely an overestimate of their effect."
These results nevertheless should allay fears that e-cigarettes might somehow make smoking more common than it would otherwise be. To the contrary, the vaping alternative seems to be accelerating the downward trend in the smoking rate, which in this survey fell from 21 percent in 2001-02 to less than 14 percent in 2014-15. Any regulatory policy that makes e-cigarettes less accessible or less appealing to smokers, such as the onerous rules unveiled by the Food and Drug Administration last year, is apt to have the opposite effect, with potentially deadly consequences.
"We found that e-cigarette use was associated with an increased smoking cessation rate at the level of subgroup analysis and at the overall population level," Zhu et al. conclude. "It is remarkable, considering that this is the kind of data pattern that has been predicted but not observed at the population level for cessation medication, such as nicotine replacement therapy and varenicline….These findings need to be weighed carefully in regulatory policy making and in the planning of tobacco control interventions."
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