Time-Varying Determinants of Changes in E-Cigarette Relative Harm Perception Among US Young Adults.

Background: Current e-cigarette use has increased among young adults in the USA despite a consistent decrease in perceiving e-cigarettes as less harmful than cigarettes over time. This study examined time-varying predictors associated with the changes in e-cigarette relative harm perception over time among US young adults.

Methods: Data were from the 2013-2018 Population Assessment of Tobacco and Health (PATH) Study for young adults (18-24 years). A time-varying effect model (TVEM) was applied to examine the association between the relative harm perception change and the associated time-varying predictors.

Results: Of the 8427 young adults, the prevalence of those who perceived e-cigarettes as less harmful than cigarettes decreased from 50.3% in Wave 1 (2013-2014) to 27.7% in Wave 4 (2016-2018). Young adults who were male were more likely to perceive e-cigarettes as less harmful than cigarettes over time (OR = 1.58; 95%CI, 1.53-1.64). In addition, the changes in e-cigarette relative harm perception were less noticeable among those with advanced degrees, who had non-combustible smoke-free home rules, who held negative tobacco-related attitudes, and those who were current e-cigarette users or ever used alcohol (all p values < 0.05).

Conclusions: A decline was observed in US young adults who perceived e-cigarettes as less harmful than cigarettes from the PATH Study across four waves (2013-2018). The study findings underscore the importance of risk communication that focuses on harm perception profiles and the need for appropriate interventions to balance the considerations of e-cigarette use among young adults.