Dear Colleagues,
I asked this question in a modified way before. Please read this text carefully before giving an answer.
Let me provide you with some background: We currently run two major school-based trials with 25.000 students total that fill out a paper pencil questionnaire in the classroom setting. We would like to validate the cigarette smoking status via a biochemical method as Gorber et al. clearly pointed out that for our target group smoking status self-reports are of limited reliability: https://www.ncbi.nlm.nih.gov/pubmed/19246437
We are interested in validating if a student smokes cigarettes or not. Please consider the following: We can not afford running two validation methods. It has to be Cotinine Saliva Testing OR Carbon Monoxide in exhaled air (via the Smokerlyzer device).
In our sample there clearly is the problem that as much students smoke e-cigarettes (which also contain nicotine) as well as cigarettes (4,7%). About 2% use both.
Cotinine saliva would not be able to determine whether a student has smoked cigarettes or e-cigarettes. So in my view CO testing would be the optimal method. However, the recent Cochrane Analysis on school-based prevention recommends Cotinine Saliva but does not even discuss how to deal with e-cigarettes as a confounder.
We monitor both on our questionnaire: Cigarette and e-cigarette use.
I strongly feel that in 2017 cotinine saliva is not the gold standard in validating smoking status anymore but CO-testing.
What is your view on this? Would you agree with my reasoning?
Thank you for your consideration of my inquiry which I highly appreciate.
Kind regards from Germany,
Titus Brinker
A smoker will have residues on finger tips that an e-smoker doesn't. It doesn't wash off easily. A touch test on sensitive paper should be definitive.
A non smoker can usually tell who is smoking what and how much by the smell.
Dear Titus,
one problem with CO-testing Gorber et al. points out is that the CO-level increases also when the individual is exposed to carbon monoxide in its surrounding environment (i.e. air pollution, environmental tobacco smoke). This may be a problem, but might be able to tolerate if you use variables to control for different aspects (i.e. number of friends, who are smoking). From a methodological perspective the review by Gobber et al. contains studies with very heterogenous study designs and samples, and there aren't shown any sensitivity analyses by study design or sample. I wouldn't base the decision just at this one study, but I think both methods have their pros and cons.
To add one more thing, e-cigarettes have been on the market since 2006, but the review was published in 2009. So, e-cigarettes might not have been in focus back then like they are right now.
Kind regards
Josefine
Assuming that you are limited to just one of the two tests, then I agree that the CO method should yield better data. I agree with Dr. Decker - there are better methods than either cotidine or CO to determine if someone is a tobacco smoker.
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