title: Differences in time to onset of smoking and nicotine dependence by race/ethnicity in a Midwestern sample of adolescents and young adults from a high risk family study.
abstract: OBJECTIVE
  The objective of this study was to determine whether race/ethnicity was associated with time to smoking initiation and time from first cigarette to onset of DSM-IV nicotine dependence (ND) after adjusting for familial and individual psychosocial risk factors.
  
  
  METHODS
  Cox proportional hazards models with time-dependent covariates were used to analyze data from 1376 offspring aged 12-33 years from 532 families at high risk for substance use problems due to paternal alcohol problems and 235 low risk families. Fifty-six percent of the sample self-identified as African-American (AA) and 44% were mainly of European descent.
  
  
  RESULTS
  Controlling for covariates, AAs began smoking at older ages (HR=0.58; 95% CI: 0.48-0.70) and had longer times between smoking initiation and onset of ND compared to non-AAs (HR=0.25, 95% CI: 0.16-0.39 for ND onset occurring <18 years and HR=0.49, 95% CI: 0.30-0.80 for ND onsets ≥ age 18). After additionally controlling for number of cigarettes smoked daily, the racial/ethnic effects for onset of ND were attenuated, but remained statistically significant for ND onset <18 (HR=0.34, 95% CI: 0.19-0.61); however, the estimate was no longer significant for later ND onset (HR=0.84, 95% CI: 0.50-1.41).
  
  
  CONCLUSIONS
  AA adolescents and young adults initiate smoking at older ages and have longer transition periods between initiation and onset of ND compared to non-AAs, even after controlling for many relevant psychiatric and psychosocial covariates; however, racial/ethnic differences in time to onset of nicotine dependence in late adolescence and young adulthood may be explained by differences in daily quantity smoked.
authors.affiliation: The Brown School, Washington University, St. Louis, MO 63130, USA. aduncan@wustl.edu
authors.forename: Alexis E
authors.initials: AE
authors.lastname: Duncan
authors.forename: Christina N
authors.initials: CN
authors.lastname: Lessov-Schlaggar
authors.forename: Carolyn E
authors.initials: CE
authors.lastname: Sartor
authors.forename: Kathleen K
authors.initials: KK
authors.lastname: Bucholz
mesh_terms: D000293:Adolescent; D000328:Adult; D001741:Black or African American; D000367:Age Factors; D017668:Age of Onset; D003627:Data Interpretation, Statistical; D039721:Diagnostic and Statistical Manual of Mental Disorders; D004522:Educational Status; D005006:Ethnicity; D005190:Family; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D015146:Midwestern United States / Q000453:epidemiology; D008923:Missouri / Q000453:epidemiology; D016016:Proportional Hazards Models; D012306:Risk; D012737:Sex Factors; D012907:Smoking / Q000453:epidemiology*; D012959:Socioeconomic Factors; D013689:Telephone; D014029:Tobacco Use Disorder / Q000453:epidemiology*; D044465:White People; D055815:Young Adult