Crack across Canada: Comparing crack users and crack non-users in a Canadian multi-city cohort of illicit opioid users.

Aims: To examine possible differences between crack users and crack non-users across Canada.

Design: Cohort study of illicit opioid and other drug users in five cities across Canada.

Setting: Vancouver, Edmonton, Toronto, Montreal and Quebec City, Canada.

Participants: Regular illicit opioid and other street drug users not in treatment at time of assessment.

Measurements: Participants (n = 677) were assessed at baseline (2002) by way of an interviewer-administered questionnaire, a psychiatric diagnostic instrument (Composite International Diagnostic Interview), and salivary antibody tests for infectious disease.

Findings: Approximately half the sample had used crack in the past 30 days, although prevalence rates differed strongly between study sites. When examined by discriminant analysis, crack users in the study population were more likely to have: no permanent housing, have illegal and sex work income, indicate physical health problems and hepatitis C virus (HCV) antibodies, use walk-in clinics, use heroin and to have been arrested and in detention (in past year). They were less likely to report depressive symptoms, and use Dilaudid (hydromorphone) and alcohol.

Conclusion: These results illustrate crack users' pronounced social marginalization (as expressed by homelessness and high involvement in illegal activities) as well as extensive health problems compared to non-crack users in the Canadian context. The development of targeted interventions-addressing the dynamics of social marginalization-of this population is urgently needed.