What do studies say about electronic cigarettes?

Editor’s Note: Just so you’re aware, comments conveying anecdotal stories or arguing that anecdotes matter here will not be approved.

I got into a twitter discussion yesterday on electronic cigarettes. Evidently, Jenny McCarthy is now pitching them. Some of us were not amused. I don’t really trust Ms. McCarthy on almost any health-related issues. But people have asked me if there is any actual harm reduction with their use. That’s a question worth asking.

I went to the medical literature. Unfortunately, there’s not much there. But here’s what I could find (with respect to clinical trials on humans):

  • A 2010 review found that lab studies show that carcinogen levels in e-cigs are much lower than traditional cigarettes. It also commented on some of the studies below.
  • A 2010 single blind randomized repeated measures cross-over trial of 40 smokers gave people (1) tobocco e-cigs, (2) placebo e-cigs, (3) nicotine inhalers, or (4) cigarettes on each of four days, three days apart, after a night of abstinence. They measured desire to smoke. The tobacco e-cigs reduced desire to smoke over the placebo, and were more well tolerated than the inhalers.
  • A 2011 prospective pilot study looked at 40 smokers who were unwilling to quit. They instead tried to get them to reduce consumption through the use of e-cigs. They found that more than half the participants reduced smoking by at least 50% at 34 weeks without significant side effects.
  • A 2012 study found that active or passive exposure to tobacco smoke increased white blood cell coulds, lymphocyte counts, and granulocyte counts for at least an hour. E-cigs did not, nor did a control situation. It’s not clear how this translates clinically, but it’s a laboratory finding in favor of e-cigs.
  • A 2012 study randomized 86 smokers to a nicotine e-cig, a placebo e-cig, or just holding the e-cig. They measured desire to smoke and withdrawal symptoms. Women had positive results with active use of either e-cig, but men did better with nicotine. There were no health outcomes.
  • An unblinded prospective 2013 study of e-cig use in 12 schizophrenic smokers for a year found that it decreased consumption without any significant side effects. Of course, this is not an RCT, and not definitive.
  • A 2013 study of 15 smokers and 15 non-smokers were exposed to nothing, tobacco smoking, and e-cig smoking (active for smokers and passive for non-smokers). Nicotine exposure, measured by cotinine levels, was similar in the two cigarette types. But lung function was impaired by traditional cigarettes, and not with e-cigs.
  • A 2013 randomized controlled trial gave 300 smokers full strength e-cigs, partial strength e-cigs, or placebo e-cigs for 12 weeks. At one year, they found that overall use and exhaled carbon monoxide declined in all three groups. But there were no differences between groups, and by a year, only 9% had quit and 10% more had a reduction. So it’s unclear if the tobacco was necessary, and how robust the results were. Here’s an article on that study.

That’s about it. If I missed anything significant, let me know.

My thoughts? If you’re looking for a means to help you quit, there’s a tiny bit of evidence that they might help, but that evidence favors placebo e-cigs about as much as tobacco e-cigs. There’s a bit of evidence that e-cigs are better than traditional cigarettes for lung function, although those studies are really small and transient. There’s also some tiny amount of evidence that e-cig smoke changes laboratory values less than the smoke of traditional cigarettes, although the clinical meaning of this is unclear. So it’s hard to get too excited about e-cigs.

But tobacco smoking is terrible, full stop. If something is less terrible, I don’t see how we totally rule that out without some thought. As pediatricians, when parents or family members can’t quit smoking, we ask them not to smoke around children. Why? Because we don’t want the perfect to be the enemy of the good. We’d rather have some improvement than none.

I don’t see enough evidence to be totally psyched about e-cigs. I wish they were better regulated. But I see enough promise to warrant some larger RCTs.


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