Hair testing and self report of cocaine use by heroin users

FRANÇAIS :
Cette étude a été menée pour identifier les facteurs de prédiction de la non révélation de l'usage de cocaïne parmi les individus s'étant auto-évalué usager d'héroïne pendant un entretien médical. Il s'agit donc d'une comparaison prospective entre l'auto-évaluation de l'usage de cocaïne parmi les héroïnomanes et l'analyse des cheveux.
ENGLISH :
Aim : 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. Design : A prospective comparison of self-report of cocaine use among heroin users and hair analysis for cocaine. Setting : Four health-care clinics at an academic, inner-city hospital. Participants : 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. Measurements : (1) Self-report using standardized instruments : the Drug Addiction Severity Tesl (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. Findings : 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 ASl 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. (Review' s abstract)