Smoking Trajectories of Adolescent Novice Smokers in a Longitudinal Study of Tobacco Use

Purpose

To describe longitudinal trajectories of smoking intensity in adolescent novice smokers and to identify predictors of trajectory class membership.

Methods

Cigarette consumption among 369 novice smokers (mean age 13 years) was measured over a mean 24 months of follow-up after smoking onset. Classes of smoking intensity trajectories were identified using latent class growth modeling. Predictors of trajectory class membership were identified in polytomous logistic regression.

Results

There was considerable between-subject heterogeneity in individual trajectories over time. Four classes of smoking intensity trajectories were identified: low-intensity, non-progressing smokers (72.4% of subjects), and slow, moderate, and rapid escalators (11.1%, 10.8%, and 5.7% of subjects, respectively). Gender, poor academic performance, and having more than half of friends who smoke at smoking onset independently predicted development of trajectory pattern. Escalating trajectory patterns were associated with earlier development of nicotine dependence and tolerance.

Conclusions

Cigarette consumption will not escalate rapidly among three-quarters of adolescent novice smokers. Novice smokers who do escalate rapidly should be targeted for early tobacco control intervention to prevent development of nicotine dependence and sustained smoking.

Introduction

Adolescent smoking is an important public health problem because of its relation to adult tobacco consumption and because its prevalence has not declined in recent years to the same extent as that of adults. In fact, smoking prevalence in adolescents increased during most of the 1990s, raising concerns about future increases in adult smoking frequency, with concomitant rises in tobacco-related morbidity and mortality.

Although most adolescents try smoking, only about 25% will become regular smokers (1). It is largely unknown how smoking intensity and frequency evolve from the earliest smoking experience of youth to adult smoking levels. Understanding the early smoking patterns of novice adolescent smokers is important for identifying youth at risk of continued smoking and for developing more intensive and effective cessation interventions tailored to the needs of specific subgroups of smokers.

Several previous studies have investigated cigarette smoking trajectories in adolescents. Chassin et al. (2) identified six classes of trajectories in subjects aged 11 to 31 years using both an a priori classification method and empirical latent class growth modeling, including stable abstainers, erratic smokers, early stable and late stable smokers, quitters, and experimenters. Colder et al. (3) identified five classes of smoking patterns in subjects aged 11 to 16 years: early rapid escalators, late moderate escalators, late slow escalators, stable light smokers, and stable puffers. However, in both studies, the follow-up was anchored at an arbitrary time zero on the scale of age, and not at the time of smoking onset. In addition, the time intervals between follow-up measurements were wide, which might not have allowed for the necessary discriminatory power of the analytical techniques utilized.

The objective of this study was to identify longitudinal trajectories of smoking intensity in adolescent novice smokers, as well as personal characteristics related to specific trajectory patterns.