The study, published in the American Journal of Public Health by researchers at the University of California, San Diego School of Medicine, found that ecigarette smokers were as much as 49% less likely to smoke fewer cigarettes -- as well as 59% less likely to quit altogether – compared to those who did use electronic cigarettes.
However, the NHS was quick to point out that the study doesn't actually prove that ecigarettes are getting in the way of smokers' quitting efforts.
For one, the biggest logical gap is this, the NHS points out: The study never set out to determine whether ecigarettes worked as a quitting aid. The subjects of the study may or may not have actually been trying to quit, so there's no telling how many of them tried and failed -- or tried and succeeded.
Additionally, other factors could have come into play, such as whether the subjects vaped between the first and second surveys, or whether they were using other kinds of quitting aids at the time.
"Ideally, a well-conducted randomised controlled trial would be needed to examine the effect of e-cigarette use on the success of people wanting to quit, comparing success rates between e-cigarette users and those using other smoking cessation methods," wrote the NHS.
There are, in fact, studies such as these.
A randomised controlled study published in The Lancet found a marginal increase in abstinence for nicotine ecigarettes versus placebo ecigarettes (over the course of 6 months), but decided that there was insufficient data to prove ecigarettes worked better than patches or placebos, but that they were "modestly effective". There was also no evidence of adverse events associated with ecigarettes.
Another English study showed that ecigarettes were about twice as effective as other nicotine replacement therapies. It wasn't a clinical trial, but the study authors did control for several factors, and it was targeted to smokers who were actually trying to quit.