In a new study published in the journal Tobacco Control a group of scientists have examined how use of e-cigarettes is related to subsequent smoking behaviour, subsequently reporting that those who use e-cigarettes are more likely to start smoking cigarettes. This new study has once again garnered the attention of the media.
As stated in the objective of the study:
Use of electronic cigarettes (e-cigarettes) is prevalent among adolescents, but there is little knowledge about the consequences of their use. We examined, longitudinally, how e-cigarette use among adolescents is related to subsequent smoking behaviour.
It is known, thanks to various surveys globally that the use of e-cigarettes has risen among teenagers, so the researchers decided to select a representative sample, follow that sample for the duration of the study (the very definition of longitudinal) to see whether any of those using e-cigarettes move on to tobacco.
From surveys that ask the right questions that the prevalence of e-cigarette use among youth is predominantly confined to those who are (or were) tobacco users, with a minimal proportion (less than 1%) having never smoked. There are also very few signs, and very little robust evidence supporting the theory that e-cigarette use leads to tobacco use.
Selecting 2,338 students in Hawaii in 2013, with a follow-up one year later (2014); which does beg the question, if this study began in 2013, and the initial completion was in 2014 why has it taken so long to release this paper?
Either way, at both intervals the researchers quizzed the participants on the use of e-cigarettes and tobacco, they asked a few questions related to other societal factors (such as “do your parents smoke”), attempted to determine if said teen was “rebellious” . They also used statistics to investigate the “relationships” between one or more factors (regression analysis) – in this case whether the use of an e-cigarette was related in any way to the onset of smoking tobacco among “never smokers” and whether or not the use of an e-cigarette affected the frequency of youth who did smoke.
Unfortunately, at the second interval (T2), only 1302 of the original 2338 participants remained, while adding an additional 434 at follow up (T2 only). An attrition of ~44% of the original participants. So a large proportion of the baseline (T1) participants did not complete T2. The major flaw here is that by adding an entirely new set of participants (which of course begs the question why were these additional 434 not in T1 in the first place) the researchers didn’t exactly follow the same sample throughout the course of the study.
Other flaws include, multiple testing – a lot of parameters were compared, each looking for a statistically significant result, which on such a fractured sample would only inflate the likelihood of finding a result when there isn’t one.
Professor Linda Bauld, professor of Health Policy at the University of Stirling, Deputy Director of UK Centre for Tobacco and Alcohol Studies published an expert reaction here and Jim McManus, Director of Public Health at Hertfordshire County Council details a number of issues for science around smoking, vaping and the health of young people in general here.
Post information provided courtesy of NNA Associate Paul Barnes.