Wednesday, May 21, 2014

New Population-Based Study Reports that E-Cigarettes Outperform NRT for Self-Assisted Smoking Cessation Among Smokers Who Choose These Approaches

A new study published online ahead of print in the journal Addiction provides evidence that electronic cigarettes may have the potential to outperform nicotine replacement therapy (NRT) for self-assisted smoking cessation.

(See: Brown J, Beard E, Kotz D, Michie S, West R. Real-world effectiveness of e-cigarettes when used to aid smoking cessation: a cross-sectional population study. Addiction. 10.1111/add.12623.)

In this cross-sectional study, a sample of adults who smoked at any point in the past 12 months was identified from a national household survey conducted in England between 2009 and 2014. Criteria for inclusion in the study were: (1) having made a serious quit attempt in the past year; (2) having used e-cigarettes alone, NRT alone, or an unaided quit attempt during their most recent quit attempt; and (3) not having used a prescription cessation drug or behavioral counseling during their most recent quit attempt.

Smoking status was then assessed at the time of the interview to determine the rates of successful quitting during the most recent quit attempt, comparing the three groups: (1) e-cigarettes only; (2) NRT only; and (3) no cessation aids. The total sample size was 5,863.

The odds ratio for successful quitting for the e-cigarette group compared to subjects who used NRT was 2.23 (95% confidence interval, 1.70-2.93).

The odds ratio for successful quitting for the e-cigarette group compared to subjects who used no cessation aid was 1.38 (95% confidence interval, 1.08-2.93).

In the above analyses, the authors controlled for level of nicotine dependence.

The study concludes: "Among smokers who have attempted to stop without professional support, those who use e-cigarettes are more likely to report continued abstinence than those who used a licensed NRT product bought over-the-counter or no aid to cessation."

The Rest of the Story

This study provides data to support the hypothesis that among smokers who choose to quit using e-cigarettes or over-the-counter nicotine replacement products (and without behavioral support), the e-cigarettes produce about a two-fold increase in the quit rate.

Readers should be cautioned that this study should not be used to conclude that e-cigarettes are twice as effective as NRT for smoking cessation generally, for reasons explained articulately by Carl Phillips in his commentary on this study.

Perhaps the most useful contribution of this paper is that it readily demonstrates why the approach being used by Stan Glantz to assess the effectiveness of e-cigarettes for smoking cessation is inappropriate and leads to erroneous conclusions.

The main difference between this study and those touted by Glantz as showing that e-cigarettes are ineffective is that unlike Glantz's cited studies, this one actually examines cessation rates among smokers who reported using e-cigarettes for smoking cessation. In other words, Brown et al. included smokers who reported having used e-cigarettes with the intention to quit smoking. In the studies cited by Glantz, smoking cessation rates for all e-cigarette users were examined, even if a smoker just tried a puff of an electronic cigarette to see what all the hype is about.

For obvious reasons, the Glantz approach is the wrong one to take, and the Brown et al. approach is correct. This study demonstrates that when you analyze the data the proper way, it appears that electronic cigarettes -- for the right smokers -- can be an effective smoking cessation tool.

The key qualifier is "for the right smokers." There is a subset of smokers who try electronic cigarettes and find them satisfactory. They may then go on to make a decision to try to quit using e-cigarettes. The results of this study do not imply that if a smoker were "forced" to use e-cigarettes to quit, one would find the same favorable results.

However, from a public health perspective, the relevant question is not what results one would obtain if smokers were forced to use a particular strategy, but what results are obtained when smokers make the choice to use a particular strategy. This is why Stan Glantz's approach is inappropriate.

Ironically, Stan Glantz criticized the study specifically because it examined the effect of electronic cigarettes on quitting among smokers who desired to quit. According to an article in the New York Times: "Stanton A. Glantz, a professor of medicine at the University of California, San Francisco, said the study’s limitation was that it tried to measure the effect of e-cigarette use only among smokers who were trying hard to quit, not all smokers."

By Stan's logic, we should throw out all the clinical trials upon which the established effectiveness of NRT is based because every one of these trials was designed to assess the efficacy of NRT among smokers who used these drugs with the specific intent to quit. Instead, according to Glantz's logic, we should examine the rate of smoking cessation among everyone who has ever used an NRT product. Doing that would lead to the conclusion that NRT is completely ineffective for smoking cessation.

The biggest problem with Stan's approach is that when you examine e-cigarette users who are not using the product to quit, you are introducing a huge sampling bias. For example, why might someone use e-cigarettes, but not to quit? Most likely, the majority of vapers who are using e-cigarettes for a purpose other than cessation are using e-cigarettes to cut down on the amount they smoke. They are likely to derive benefits from smoking reduction. However, they are almost assuredly not going to quit smoking because they are not trying to quit, nor do they have such a desire. 

The rest of the story is that if you ask the wrong question, you are going to get the wrong answer. By asking the wrong question about the effectiveness of electronic cigarettes, Dr. Glantz has obtained the wrong answer.

From a public health perspective, the effectiveness of e-cigarettes for smoking cessation must be assessed by examining how effective the product is for smokers who are trying to quit. When you do that properly, this initial evidence suggests that you find out e-cigarettes are a viable smoking cessation aid for a subset of smokers.

The degree to which electronic cigarettes stimulate or depress overall interest in quitting is a separate and empirically answerable question. In fact, evidence from the UK indicates that the spread of electronic cigarettes has been associated with a substantial increase in the desire to quit smoking at a population level.

1 comment:

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