Age at Initiation of Cigarette Use in a Nationally Representative Sample of US Youth, 2013-2017.

Importance: Cigarettes are still a commonly used tobacco product among youth despite recent declines in cigarette use. Objective: The aim of this study was to prospectively estimate the age of cigarette use initiation among youth (aged 12-17 years) overall, by sex, and by race/ethnicity. Design, Setting, and Participants: This cohort study used data from waves 1 through 4 of the nationally representative Population Assessment of Tobacco and Health (PATH) study, conducted from September 12, 2013, to January 3, 2018. Two subpopulations of youth were assessed: (1) those nonsusceptible to cigarette use and (2) never users of cigarettes at their first wave of PATH participation. Weighted interval-censoring survival analyses were used to prospectively estimate the age of initiation of cigarette use outcomes. Weighted interval-censoring Cox proportional hazard models were used to estimate differences in the age of initiation by sex and by race/ethnicity. Statistical analyses were performed from October 7, 2019, to May 1, 2020. Exposures: Differences in the age of initiation by sex and race/ethnicity. Main Outcomes and Measures: Age of initiation of susceptibility to cigarette use, ever use, past 30-day use, and fairly regular cigarette use overall, by sex, and by race/ethnicity. Results: A total of 15 776 youth never users and, among them, 11 022 youth who were nonsusceptible to cigarette use, were included in this study (weighted mean [SE] age, 13.5 [0.01] years; 58.6% [SE, 0.46%] non-Hispanic White; and 51.0% [SE, 0.32%] boys) and 15 776 were never users of cigarettes at their first wave of PATH participation (weighted mean [SE] age, 13.7 [0.01] years; 55.0% [SE, 0.29%] non-Hispanic White; and 51.0% [SE, 0.15%] boys). By age 18 years, among those who were nonsusceptible, 46.2% (95% CI, 44.3%-48.2%) became susceptible to cigarette use. Among never users, 24.4% (95% CI, 22.9%-25.9%) initiated ever cigarette use, 16.4% (95% CI, 15.2%-17.6%) initiated past 30-day cigarette use, and 4.3% (95% CI, 3.9%-4.8%) initiated fairly regular cigarette use. Boys had a higher risk of initiating ever (hazard ratio [HR], 1.21; 95% CI, 1.08-1.36) and past 30-day cigarette use (HR, 1.27; 95% CI, 1.10-1.47) at earlier ages compared with girls. Non-Hispanic White youth had a higher risk of an earlier age of initiation of susceptibility to cigarette use (HR, 0.77; 95% CI, 0.68-0.88), ever use (HR, 0.59; 95% CI, 0.49-0.71), past 30-day use (HR, 0.64; 95% CI, 0.52-0.77), and fairly regular cigarette use (HR, 0.25; 95% CI, 0.14-0.43) compared with non-Hispanic Black youth. Conclusions and Relevance: The results of this cohort study suggest that, despite current interventions and existing laws, a large number of youth initiated cigarette use before the legal age to purchase tobacco products.