Tobacco and nicotine use among US adult "never smokers" in Wave 4 (2016-2018) of the Population Assessment of Tobacco and Health Study.

INTRODUCTION A common criterion for being labeled a "never smoker" is having smoked <100 lifetime cigarettes. This category is often used as an unexposed reference group to estimate the relative harm from cigarettes. We examined the amount of current and past cigarette and non-cigarette tobacco/nicotine use among adults who met this "never smoker" criterion. METHODS We analyzed cross-sectional data from 17,179 adult "never smokers" (i.e., reported <100 lifetime cigarettes) in Wave 4 (2016 to 2018) of the Population Assessment of Tobacco and Health (PATH) Study, a United States nationally representative sample. We used PATH-derived variables to describe "never smokers'" demographics as well as cigarette and non-cigarette tobacco use. RESULTS Approximately half of "never smokers" were young adults (49.3%). Most were white (68.6%) with some college or more (64.4%). Most "never smokers" had tried any cigarette or non-cigarette tobacco/nicotine in their lifetime (66.7%), 8.5% smoked cigarettes in the past 30 days, and 5.3% were current experimental (i.e., some days or every day) cigarette smokers. By definition, "never smokers" reported smoking <100 lifetime cigarettes. One fifth (22.8%) had a lifetime history of established regular non-cigarette tobacco/nicotine use and 8.6% were current established regular non-cigarette tobacco/nicotine users. In total, 9.4% of "never smokers" were current experimental or established regular users of combustible tobacco. CONCLUSIONS The 100-cigarette lifetime threshold includes substantial amounts of current and past tobacco use and thus does not represent lack of exposure to cigarette or non-cigarette tobacco. "Never smoker" reference groups may produce underestimates of the relative harms from cigarettes. IMPLICATIONS The <100 lifetime cigarettes criterion may not capture what many would consider true "never smokers." Relying on the current definition of "never smokers" as a reference group will include a substantial number of those currently and recently using combustible tobacco and thus produce data that may underestimate the relative harm from cigarettes. Prospective longitudinal research is needed to compare how the 100-cigarette lifetime threshold versus other definitions of regular cigarette smoking differ in predictive validity of clinically meaningful outcomes and health harms to determine the optimal criteria to define established cigarette smoking.