Determinants of Waterpipe Smoking Trajectories and the Effects of Pictorial Health Warning Label among Young Waterpipe Smokers in the US

In recent years waterpipe tobacco (WPT) smoking has increased among young people in the United States (US). Adequate characterization of the WPT smoking trajectories (initiation, progression, and cessation), their predictors, and examination of the effects of a pictorial health warning label (PHWL) on WPT smokers is essential to guide interventions and policies to curb WPT smoking among young people in the US. Using the Population Assessment of Tobacco and Health Study (PATH) and clinical lab data, this dissertation assessed: 1) prevalence and predictors of WPT smoking initiation and progression among adolescents and young adults; 2) magnitude and predictors of WPT cessation among young adults, and 3) the effects of PHWL on low- and high-frequency WPT smokers’ experiences, toxicant exposures, and puffing behavior. In the first study, between 2013-2018, 4.8% of the adolescents and 18.5% of young adults initiated WPT smoking. During the same period, 10.6% of adolescent WPT smokers and 14.1% of young adult-WPT smokers progressed in WPT smoking (increase in the frequency of smoking at any subsequent wave). Predictors of WPT initiation among adolescents include lower harm perception (adjusted odds ratio (aHR)=2.89, 95% confidence interval (CI)=2.10-3.98), and other tobacco products use (aHR=3.97, 95% CI=2.73-5.78), while predictors of WPT progression include illicit drug use (aHR=4.60, 95% CI=1.99-10.67). Among young adults, predictors of WPT initiation include lower harm perception (aHR=2.77, 95% CI=2.19-3.50), and other tobacco products use (aHR=3.14, 95% CI=2.25-4.38); while predictors of WPT progression were lower harm perception (aHR=1.80, 95% CI=1.41-2.30), and alcohol use (aHR=1.61, 95% CI=1.13-2.30). In the second study, 25.13% of the young adult WPT smokers quit smoking between waves 1-5 (2015-2019). The major predictor of WPT smoking cessation was regretting smoking (aHR= 2.33, 95% CI=1.29-4.21) whereas barriers to cessation were the lack of smoking restriction