Abstract
INTRODUCTION: More than 10% of U.S. young adults have smoked waterpipe tobacco in the past month and >25% of those who have never smoked are susceptible. We tested messages designed to prevent and reduce waterpipe tobacco smoking (WTS). METHODS: In 2020, we recruited 830 U.S. young adults (18-30 years) who had never smoked waterpipe tobacco and were susceptible or currently smoked waterpipe tobacco for an online study. We randomized participants to intervention messages about the risks of WTS or control messages unrelated to tobacco. Participants had up to four message exposures over 12 weeks and completed two-, four-, and six-month follow-ups. Outcomes were WTS initiation and curiosity (susceptible never smokers), WTS frequency, cessation, motivation to quit (those who currently smoked), and WTS risk perceptions. RESULTS: Intervention messages increased perceived addictiveness of WTS at two months (β = 0.27; 95% CI: 0.11, 0.43) in susceptible never smokers. There were no significant intervention effects in those who currently smoked. Exploratory analyses among intervention participants showed that higher dose of message exposure decreased WTS initiation at six months in susceptible never smokers (RR = 0.68; 95% CI: 0.48, 0.96) and decreased WTS frequency (IRR = 0.84; 95% CI: 0.73, 0.97) and increased cessation (RR = 1.31; 95% CI: 1.07, 1.59) at six months in those who smoked. CONCLUSIONS: Although the WTS intervention messages had few significant effects on outcomes overall, a higher dose of message exposure affected behavioral outcomes in the intervention arm. Findings highlight the need to identify effective message content and optimal message dose, especially for digital media campaigns.