The proper approach to assessing the impact of the fact that e‐cigarettes were not available before 2007

• Published in: Addiction (Abingdon, England) Vol. 115; no. 11; pp. 2180 - 2182
• Main Authors: Bhatta, Dharma N., Glantz, Stanton A.
• Format: Journal Article
• Language: English
• Published: England Blackwell Publishing Ltd 01.11.2020
• Subjects: Addictive behaviors; Cigarettes; Electronic cigarettes; Electronic Nicotine Delivery Systems; Humans; Myocardial Infarction; Nicotine; Smoking; Vaping
• ISSN: 0965-2140; 1360-0443
• DOI: 10.1111/add.15103

In a cross-sectional study, one computes the association between exposures (in this case e-cigarette and cigarette use) and an outcome (in this case having had an acute myocardial infarction) among data observed at a fixed point in time. In this case the specific issue is whether the myocardial infarctions may have occurred before e-cigarette use. Rodu & Plurphanswat provided an alternative analysis of the Population Assessment of Tobacco and Health (PATH) data set to one we published, that found an association between having had a myocardial infarction and e-cigarette use. Their analysis selectively changes data for e-cigarette users who started using e-cigarettes before their myocardial infarction, which is inappropriate in a cross-sectional study. Their inappropriate analysis led to the biologically implausible result that non-daily e-cigarette use was protective against myocardial infarction. A standard cross-sectional analysis that treats all exposure groups the same is the appropriate way to do such studies.