Age of Onset of Susceptibility to Different Tobacco Products Among Non-Susceptible US Young Adults: Findings from the Population Assessment of Tobacco and Health Study Waves 2-4 (2014-2017).

Introduction: Initiation of tobacco products is increasing in young adulthood. This study prospectively estimated the age of onset of susceptibility to cigarettes, e-cigarettes, hookah, smokeless tobacco, and cigarillos among young adults, which is a cognitive precursor to initiation.

Methods: Secondary data analyses of the Population Assessment of Tobacco and Health (PATH) study, a nationally representative longitudinal cohort study of US adults. Young adults (18-24 years) who were non-susceptible to each tobacco product (cigarettes, e-cigarettes, hookah, smokeless tobacco, and cigarillos) at waves 2 or 3 were followed-up into waves 3-4 to prospectively estimate the age of onset of susceptibility to each tobacco product. Weighted interval-censored survival methods and interval-censored Cox regression models were implemented to estimate the age of onset of susceptibility, and to estimate differences in the hazard function by sex and by race/ethnicity, while controlling for the total number of other tobacco products ever used at their first wave of participation in PATH.

Results: By age 21, 16.5%, 16.0%, 12.6%, 12.4%, and 5.9% of young adults reported onset of susceptibility to hookah, e-cigarettes, cigarillos, cigarettes, and smokeless tobacco, respectively. Among young adults who were non-susceptible to each tobacco product at waves 2 or 3, the highest increase in onset of susceptibility occurred between ages 18 and 19 for cigarettes, e-cigarettes, and hookah, while the highest increase in onset of susceptibility occurs between ages 22 and 23 for cigarillos. Young adult males had increased risk of onset of susceptibility to cigarillos and smokeless tobacco at earlier ages than young adult females. Differences in onset of susceptibility to each tobacco product were also observed by race/ethnicity among young adults.

Conclusions: With the changing landscape of tobacco products, monitoring the age of onset of susceptibility of tobacco product use among non-susceptible young adults longitudinally is critical to prevent initiation. Communication and education campaigns tailored to address differences in susceptibility among young adults by tobacco product and sociodemographic factors will be useful.