Risk of adolescent cigarette use in three UK birth cohorts before and after e-cigarettes

Objective: Longitudinal data from three UK birth cohorts (born in 1958, 1970 and 2001) were used to (1) document the historic decline in adolescent cigarette smoking; (2) examine how e-cigarette use is associated with adolescent cigarette smoking in the most recent cohort; and (3) compare probabilities of cigarette smoking across the cohorts. Methods: The prevalence of adolescent cigarette smoking was assessed in 1974 from 11 969 youth in the National Child Development Study (NCDS), in 1986 from 6222 youth in the British Cohort Study (BCS), and in 2018 from 9733 youth in the Millennium Cohort Study (MCS). Logistic regression models were used to estimate the odds of adolescent smoking (ages 16-17) based on a common set of childhood risk and protective factors; adolescent e-cigarette use was included as a predictor in the more recent MCS. Results: Adolescent cigarette smoking declined from 33% in 1974 to 25% in 1986 and to 12% in 2018. 11% of MCS youth reported current e-cigarette use. Though childhood risk factors for later adolescent smoking were mostly similar across the three cohorts, the risk of cigarette smoking in the MCS varied greatly by e-cigarette use. Among MCS youth, the average predicted probability of smoking ranged from 1% among e-cigarette naïve youth to 33% among youth currently using e-cigarettes. Conclusions: Adolescents who use e-cigarettes have a similar smoking prevalence to earlier generations. Policy and prevention should seek to prevent adolescent nicotine exposure via both electronic and combustible cigarettes.