Initiation, Progression, and Sustained Waterpipe Use: A Nationally Representative Longitudinal Study of U.S. Young Adults.

Waterpipe tobacco smoking (WTS) is increasing in popularity despite evidence of harm and potential for dependence. Intervention development has been hampered by a lack of longitudinal, nationally representative data on usage patterns and factors independently associated with WTS initiation. Therefore, we aimed to characterize key transitions between WTS states in a nationally representative group of young adults, with particular attention to factors independently associated with initiation. Participants were randomly selected from a national probability-based panel representing 97% of the United States. A total of 1,785 adults ages 18 to 30 at baseline completed two Web-based surveys 18 months apart in 2013 and 2014. Assessments included knowledge of waterpipe tobacco smoke composition, positive and negative attitudes toward WTS, normative beliefs, intention to use waterpipe, and WTS behavior. We used multivariable logistic regression to assess the association between predictive factors and subsequent WTS initiation. In fully adjusted models, overall knowledge about toxicants associated with WTS was not associated with subsequent WTS initiation. Similarly, negative attitudes and normative beliefs were not associated with WTS uptake. However, baseline positive attitudes were strongly and significantly associated with WTS initiation [adjusted OR (AOR) = 1.7; 95% confidence interval (CI), 1.2-2.3]. Similarly, baseline intention to use WTS was strongly associated with subsequent initiation (AOR = 7.0; 95% CI, 3.5-13.7). Prevention efforts may be most successful if they target individuals with clear intentions to use WTS and challenge positive attitudes surrounding WTS. Surveillance of WTS trajectories will help inform health care and policy surrounding this emerging risk behavior among U.S. young adults. .