Determining the probability of future smoking among adolescents.

AIMS: To determine whether the probability of future current established smoking among adolescents is related to both previous smoking experience and cognitions regarding future smoking. DESIGN, SETTING AND PARTICIPANTS: The analyses used two principal datasets: (1) a US longitudinal sample of 7960 adolescents 12-18 years old in 1989 reinterviewed at 15-22 years in 1993, (2) a California longitudinal sample of 3376 adolescents 12-17 years old in 1993 reinterviewed at 15-20 years in 1996. MEASURES: Previous smoking experience was categorized as never smoked, puffed, non-recent or recent experimenting, and non-recent or current established smoking (> or = 100 cigarettes in life-time). Smoking intentions and efficacy expectations were used to classify adolescents as having low- or high-risk cognitions.
FINDINGS: High-risk cognitions (HRCs) increased the probability of future current established smoking (FCES) within each level of previous smoking experience over low-risk cognitions (LRCs); the probability of FCES for those with LRCs was about the same as those in the previous experience group with HRCs. In the US sample, the 4-year probability of FCES ranged from 5.6% for committed never smokers (with LRCs) to 83.0% for current established smokers with HRCs. Development of HRCs among middle-school never smokers occurred rapidly through age 14 years. However, current established smoking did not increase until age 14 years and stabilized by age 19 years. Where sample size was sufficient, these findings were validated in the California sample.
CONCLUSIONS: Effective prevention programs should aim to convert HRCs to LRCs regardless of past behavior, particularly among middle-school never smokers and high-school experimenters.