title: The role of parental consent in adolescent substance use research.
abstract: OBJECTIVE
  The objective of our study was to assess the effects of requiring parental consent upon study participation and self-reported substance-related problems among 14-18-year-olds.
  
  
  METHODS
  This was a secondary analysis of combined data from two similar studies of adolescent substance use that recruited participants from the same adolescent clinic at Children's Hospital Boston. Study 1 waived parental consent, whereas Study 2 required parental consent. The combined dataset included demographic characteristics and Car, Relax, Alone, Forget, Friends, Trouble (CRAFFT) study screening test responses. The CRAFFT is an orally administered screen that yields a score from 0-6 and that has been shown to be a valid and reliable measure of risk for substance-related problems.
  
  
  RESULTS
  The participation refusal rate in Study 1, where consent was waived, was 19.7% (132 of 670 eligible individuals) and in Study 2 (243 of 411 eligible individuals), where consent was required, it was 59.1% (p < .0001). Participants did not differ significantly with respect to gender and age but did differ by self-identified race/ethnicity between the two studies. Because the CRAFFT score distributions were highly skewed, we used the nonparametric Mann-Whitney U test for differences in mean rank. The mean rank in Study 1 was significantly higher than in Study 2 (mean rank 362 vs. 325, p = .02). After controlling for age, gender, and race/ethnicity, the adjusted proportional odds ratio for a one-point increase in CRAFFT score was 1.47 (CI 1.03, 2.10) for Study 1 compared with Study 2.
  
  
  CONCLUSIONS
  The research requirement of parental consent may result in substantial self-selection bias towards a lower risk sample.
authors.affiliation: Center for Adolescent Substance Use Research, Children's Hospital Boston, Boston, Massachusetts 02115, USA. rojas.neal@gmail.com
authors.forename: Neal L
authors.initials: NL
authors.lastname: Rojas
authors.forename: Lon
authors.initials: L
authors.lastname: Sherrit
authors.forename: Sion
authors.initials: S
authors.lastname: Harris
authors.forename: John R
authors.initials: JR
authors.lastname: Knight
mesh_terms: D000293:Adolescent; D017677:Age Distribution; D035843:Biomedical Research; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008404:Massachusetts / Q000453:epidemiology; D010287:Parent-Child Relations; D033282:Parental Consent; D010358:Patient Participation; D011336:Probability; D017678:Sex Distribution; D018709:Statistics, Nonparametric; D015813:Substance Abuse Detection / Q000379:methods*; D019966:Substance-Related Disorders / Q000175:diagnosis / Q000453:epidemiology*