title: Hair testing and self-report of cocaine use by heroin users.
abstract: OBJECTIVE
  Failure to disclose cocaine use can have a negative impact on medical care and research validity. This study was performed to identify predictors of cocaine non-disclosure among individuals who self-reported heroin use during a medical care encounter.
  
  
  METHODS
  A prospective comparison of self-report of cocaine use among heroin users and hair analysis for cocaine.
  
  
  METHODS
  Four health-care clinics at an academic, inner-city hospital.
  
  
  METHODS
  Patients presenting for a health-care visit who were willing to self-report use of heroin and were not engaged in any form of drug treatment.
  
  
  METHODS
  (1) Self-report using standardized instruments: the Drug Addiction Severity Test (DAST), the Addiction Severity Index (ASI) and quantity/frequency questions for heroin and cocaine use. (2) Biochemical evidence: analysis of hair by radioimmunoassay (RIA) for cocaine and opiate levels.
  
  
  RESULTS
  Among 336 heroin users who tested positive for cocaine in hair, 34.2% did not report their recent cocaine use. The mean cocaine level for discordant individuals was significantly lower than for concordant individuals (109.6 ng/10 mg versus 470.57 ng/10 mg; P < 0.0001). Multivariate predictors of disclosure included opiate and cocaine levels in hair and the ASI drug severity subscore.
  
  
  CONCLUSIONS
  Although self-report has been validated for treatment system patients, almost a third of the out-of-treatment heroin users in this medical clinic study failed to disclose concomitant cocaine use. The likelihood of non-disclosure was greatest for heavy users of heroin and light users of cocaine. Confirmation of self-report with biochemical analysis in the medical setting may be necessary to improve both clinical care and research validity.
authors.affiliation: Boston University School of Public Health, Boston, MA 02118, USA.
authors.forename: Katherine
authors.initials: K
authors.lastname: Tassiopoulos
authors.forename: Judith
authors.initials: J
authors.lastname: Bernstein
authors.forename: Timothy
authors.initials: T
authors.lastname: Heeren
authors.forename: Suzette
authors.initials: S
authors.lastname: Levenson
authors.forename: Ralph
authors.initials: R
authors.lastname: Hingson
authors.forename: Edward
authors.initials: E
authors.lastname: Bernstein
mesh_terms: D000328:Adult; D003042:Cocaine / Q000032:analysis*; D019970:Cocaine-Related Disorders / Q000175:diagnosis* / Q000453:epidemiology / Q000523:psychology; D005260:Female; D006197:Hair / Q000737:chemistry*; D006556:Heroin Dependence / Q000175:diagnosis*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011863:Radioimmunoassay; D012650:Self Disclosure; D015813:Substance Abuse Detection / Q000379:methods*
chemical_list: D003042:Cocaine