Young Adult Tobacco and E-cigarette Use Transitions: Examining Stability Using Multistate Modeling
Abstract Introduction The objective of this study was to describe tobacco and nicotine product use state transition probabilities among youth and young adults over time. Methods A national sample of young adult tobacco product users and nonusers between the ages of 18 and 34 years at baseline was surveyed at 6-month intervals for 3 years. Use and nonuse states were defined as mutually exclusive categories based on self-reported, past 30-day use of the various products. Never use, noncurrent use, and current use of combustible, noncombustible tobacco, and electronic cigarette (e-cigarette) products was assessed at each interval. A multistate model was fit to estimate transition probabilities between states and length of stay within each state. Results After 6 months, same-state transition probabilities were high for all use states (0.76–0.96), except for dual product use (0.48). After 3 years, transition probabilities were smaller and tended to converge toward combustible product use for baseline e-cigarette (0.42), combustible (0.51), and dual product users (0.52). Age was inversely associated with transition risk from never or noncurrent use to use of combustible or e-cigarette products. Conclusions Never and noncurrent users, followed by combustible product users, were most likely to remain in those states throughout the 3-year observation interval. Users of any tobacco or e-cigarette product at baseline were most likely to transition to combustible product use or noncurrent use by the final follow-up. Implications This study describes the probability of transitioning between various states of tobacco product use, including never and no current use, over a span of 3 years in a sample of young adults. This type of longitudinal description, which includes all tobacco product use states, is lacking in most studies that tend to focus on one or only a few products. The results suggest that it is important to assess outcomes over a sufficiently long period to capture true variability in patterns of product use.