Cannabis abuse is not a risk factor for treatment outcome in methadone maintenance treatment: a 1-year prospective study in an Israeli clinic.

<h4>Objective</h4>We addressed the following questions. What are the current and lifetime prevalence of cannabis abuse in an Israeli methadone maintenance treatment (MMT) clinic? Does cannabis abuse change over time during MMT? Is cannabis abuse related to treatment outcome measures such as retention rate and the abuse of drugs? Is the abuse of cannabis related to psychopathology, HIV/HCV risk-taking and infectious diseases? Do cannabis abusers (CAs) have a different psychosocial and demographic profile than nonabusers (NCAs)? Is cannabis abuse part of a polydrug abuse tendency or a distinct substance of abuse?<h4>Method</h4>Overlapping samples of either the entire clinic population (n = 283) or all the patients who had completed 1 year of MMT treatment (n = 196 of which 20 were re-entering) underwent random and twice-weekly observed urine analysis for various drugs of abuse, responded to self-report questionnaires (SCL-90-R; HIV/HCV risk-taking behaviours; n = 164), interviews (ASI, n = 176; SCID, n = 151) and hepatitis C and HIV testing (n = 149).<h4>Results</h4>Lifetime abuse prevalence was found in 75% and current abuse at MMT intake in 25%. Abuse did not increase significantly over a 1-year period. Cannabis abusers were found to be more often polydrug abusers than NCAs. Cannabis abusers did not suffer from more psychological distress, infectious diseases, and did not engage in more HCV/HIV risk-taking behaviour, nor did they leave treatment earlier than NCAs.<h4>Conclusions</h4>Cannabis abuse MMT patients should be treated as polydrug abusers, although no specific influences of cannabis abuse on psychological and medical conditions of MMT patients have been observed. Treatment policy should take these results into consideration.