Evidence that e-cigs depress quitting cigarettes keeps piling up, this time from Japan

Tomoyasu Hirano and colleagues just published “Electronic Cigarette Use and Smoking Abstinence in Japan: A Cross-Sectional Study of Quitting Methods” that adds to the already-strong case that smokers who use e-cigarettes are less, not more, likely to quit smoking.
They conducted a national cross-sectional study of 9055 people in Japan who had tried to quit smoking cigarettes in the last 5 years and found that people who used e-cigarettes were 38% less likely to have stopped smoking than people who didn’t use e-cigarettes.  This finding of about a 1/3 drop in the odds of having quit is consistent with the meta-analysis of the entire available literature – including the few papers that showed increased quitting among e-cigarette users -- we published last year as well as other results published since then.
Here is the abstract:

The benefit of electronic cigarettes (e-cigarettes) in smoking cessation remains controversial. Recently, e-cigarettes have been gaining popularity in Japan, without evidence of efficacy on quitting cigarettes. We conducted an online survey to collect information on tobacco use, difficulties in smoking cessation, socio-demographic factors, and health-related factors in Japan. Among the total participants (n = 9055), 798 eligible persons aged 20–69 years who smoked within the previous five years were analyzed to assess the relationship between the outcome of smoking cessation and quitting methods used, including e-cigarettes, smoking cessation therapy, and unassisted. E-cigarette use was negatively associated with smoking cessation (odds ratio (OR) = 0.632; 95% confidence interval (CI) = 0.414–0.964) after adjusting for gender, age, health-related factors, and other quitting methods. Conversely, smoking cessation therapy (i.e., varenicline) was significantly associated with smoking cessation (OR = 1.885; 95% CI = 1.018–3.492) in the same model. For effective smoking cessation, e-cigarette use appears to have low efficacy among smokers in Japan. Allowing for the fact that this study is limited by its cross-sectional design, follow-up studies are needed to assess the prospective association between e-cigarette use and smoking cessation.

My one quibble with the way the authors summarize their conclusions is their statement that “e-cigarette use appears to have low efficacy in Japan.”  This statement could be read as saying that e-cigarettes help people quit, just not by much.  What the data show is that e-cigs significantly depress quitting.
The full citation is:  Tomoyasu Hirano, Takahiro Tabuchi, Rika Nakahara, Naoki Kunugita, Yumiko Mochizuki-Kobayashi.  Electronic Cigarette Use and Smoking Abstinence in Japan: A Cross-Sectional Study of Quitting Methods. Int. J. Environ. Res. Public Health 2017, 14(2), 202; doi:10.3390/ijerph14020202.  The free full text is available at http://www.mdpi.com/1660-4601/14/2/202/htm