title: Hazard of smoking initiation by age among adolescents in Wuhan, China.
abstract: BACKGROUND
  Knowledge about age of smoking initiation among adolescents in China is helpful for exploring cultural differences in adolescent smoking behavior and informative for global tobacco control. However, little has been documented on this issue.
  
  
  METHODS
  Adolescents (6,473) attending grades 7, 8, and 9 completed the baseline survey of a longitudinal, randomized smoking prevention trial. Data were collected in classrooms with a paper-and-pencil questionnaire. A survival model was used in the statistical analysis.
  
  
  RESULTS
  The hazard of smoking initiation for boys showed a pattern previously observed in the United States: very low (<2%) before 7 years of age, increasing rapidly after age 10, and peaking at 14-15 years of age. The hazard for girls was below or around 1% until 12 years of age before it increased. The hazard levels were similar for adolescents both in urban and in rural areas, but higher for those in grade 7 than in grades 8 and 9.
  
  
  CONCLUSIONS
  Chinese boys in Wuhan, China, experienced a hazard pattern of smoking initiation by age similar to those observed in the United States, while Chinese girls there experienced a rather low risk of smoking initiation. The hazard pattern suggests that the best time for smoking prevention is between 10 and 15 years of age. Adolescents in lower grades are at higher risk of early smoking initiation, suggesting a potential cohort effect in adolescent smoking initiation in Wuhan, China.
authors.affiliation: Institute for Health Promotion and Disease Prevention Research, University of Southern California School of Medicine, 1540 Alcazar Street, Los Angeles, CA 90089-9008, USA. xinguang@hsc.usc.edu
authors.forename: X
authors.initials: X
authors.lastname: Chen
authors.forename: Y
authors.initials: Y
authors.lastname: Li
authors.forename: J B
authors.initials: JB
authors.lastname: Unger
authors.forename: J
authors.initials: J
authors.lastname: Gong
authors.forename: C A
authors.initials: CA
authors.lastname: Johnson
authors.forename: Q
authors.initials: Q
authors.lastname: Guo
mesh_terms: D000293:Adolescent; D000294:Adolescent Behavior; D000367:Age Factors; D002648:Child; D002681:China / Q000453:epidemiology; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D012907:Smoking / Q000453:epidemiology*; D000074606:Smoking Prevention; D016019:Survival Analysis