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PATTERNS OF DRUG USE FOLLOWING THE INITIATION OF METHADONE MAINTENANCE TREATMENT
Mark W Tyndall, N Laliberte, P Spittal, K Li, M O’Shaughnessy, MT Schechter
Vancouver Injection Drug User Study, British Columbia Centre for Excellence in HIV/AIDS
Background: Methadone Maintenance Treatment (MMT) is the cornerstone of therapy for opiate dependency. In view of the large numbers of untreated opiate addicts in Canada, it is widely believed that MMT is severely underutilized. We studied the impact of MMT on a cohort of injection drug users (IDUs) in order to evaluate changes in behaviors and drug use patterns following MMT initiation.
Methods: The Vancouver Injection Drug Users Study (VIDUS) is an open prospective cohort that has enrolled over 1,400 IDUs between May 1996 and December 2000. Follow-up visits are conducted every six months, at which time a detailed questionnaire is administered and blood testing is done. We identified 263 MMT-naive participants who subsequently began MMT during follow-up. Behavioral and drug use information was compared using data from the first MMT visit with the visit prior to MMT. McNemar’s test was used to detect changes.
Results: The initiation of MMT was associated with a reduction in daily heroin use (78% vs 61%, p=0<0.001), nonfatal drug overdose (26% vs 10%, p<0.001), working in the sex trade (27% vs 22%, p=0.02), being incarcerated (43% vs 32%, p<0.001), and visiting the needle exchange (77% vs 63%, p=0<0.001). There was an increased likelihood of accessing government welfare payments (62% vs 75%, p<0.001). There was a trend toward less daily injection cocaine use (37% vs 31%, p=0.09), and less daily crack cocaine use (18% vs 16%, p=0.42), although these did not reach statistical significance. Regular use of alcohol remained unchanged (36% vs 36%, p=0.91).
Conclusions: Following the initiation of MMT there was a marked reduction in nonfatal overdoses, sex trade work, and incarcerations, with a modest reduction in overall drug use. This data clearly supports the use of MMT as a harm reduction strategy, while recognizing that continued injection and noninjection drug use is common.