title: How have smoking risk factors changed with recent declines in California adolescent smoking?
abstract: OBJECTIVE
  To compare predictors of smoking initiation in two longitudinal studies in California conducted during periods when adolescent smoking prevalence was increasing (1993-96) and decreasing (1996-99).
  
  
  METHODS
  Cohorts of 12-15-year-old never smokers were identified from the cross-sectional 1993 and 1996 California Tobacco Surveys (large population-based telephone surveys) and followed-up 3 years later (1993-96, n = 1764; 1996-99, n = 2119).
  
  
  METHODS
  We compared cohort transition rates to any smoking by follow-up in risk groups defined by known predictors of smoking initiation at baseline. Besides examining predictors individually, risk groups were defined using a multivariate analysis.
  
  
  RESULTS
  Overall, transition to any smoking by follow-up occurred in 38.3 +/- 4.0% (% +/- 95% confidence interval) of never smokers in the 1993-96 cohort and 31.1 +/- 2.6% in the 1996-99 cohort. For most predictors, the transition rate for adolescents with the characteristic was the same or only slightly lower in the 1996-99 cohort compared to the 1993-96 cohort, but the transition rate in those without the characteristic was generally much lower, thus increasing the power of the predictor. The multivariate analysis confirmed that compared to the 1993-96 cohort, transition occurred much less often in the 1996-99 cohort for adolescents at low rather than at medium or high risk of future smoking.
  
  
  CONCLUSIONS
  The turnaround in California adolescent smoking in the mid-1990s, when smoking began to decline, appears to come primarily from adolescents already at low risk of future smoking (as defined by a variety of predictors), who transitioned to smoking at much lower rates than previously.
authors.affiliation: Cancer Prevention and Control Program, Cancer Center, University of California, San Diego, La Jolla, CA 92093, USA.
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Gilpin
authors.forename: Lora
authors.initials: L
authors.lastname: Lee
authors.forename: John P
authors.initials: JP
authors.lastname: Pierce
mesh_terms: D000293:Adolescent; D001294:Attitude to Health; D002140:California / Q000453:epidemiology; D002648:Child; D005260:Female; D006801:Humans; D016015:Logistic Models; D008137:Longitudinal Studies; D008297:Male; D012307:Risk Factors; D012907:Smoking / Q000453:epidemiology* / Q000523:psychology*