Ying MacNab

Background: Opioid dependence is a chronic disease characterized by periods of relapse and remission. Methadone maintenance treatment (MMT) can be effective, though not all patients can be successfully maintained in treatment. Further, treatment entrants often use multiple illicit drugs, a fact whose motive and effect are under-studied. Rigorous evaluation at the aggregate- and patient-level is required to maximize the public health benefits of substance abuse treatment. Objectives: (1) identify the determinants of the time to discontinuation of MMT across multiple treatment episodes; (2) determine the effect of price on drug consumption among polydrug users; (3) identify trends in compliance to MMT dosing guidelines in British Columbia, Canada from 1996-2007; (4) provide a comparative analysis of the psychometric properties of eight measures of health status for opioid users; (5) evaluate differences in trajectories of health status among opioid users following treatment enrolment.Methods: We draw upon longitudinal data collected in administrative databases (study 1 and 3), experimental (study 4 and 5) and observational cohort studies (study 2) to shed light on the life course of treatment and relapse that opioid addicts experience, their decisions to consume addictive substances, and treatment evaluation at the aggregate- and patient-levels.Results: This collection of studies found (1) patients experiencing multiple treatment episodes tended to stay in treatment for progressively longer periods in later episodes; (2) While heroin and crack cocaine were price inelastic polydrug users treated crack cocaine as a substitute for heroin. In terms of treatment evaluation at the aggregate-level, compliance to minimally effective dose guidelines, along with 12-month retention figures have fallen in the past 5 years in British Columbia (study 3). At the patient-level each of the health status measures assessed in the North American Opiate Medication Initiative (NAOMI) trial showed limitations (study 4), however health status can be meaningfully improved through effective, patient-centered opioid substitution treatment (study 5). Conclusions: The results of these novel empirical studies suggest that while MMT can be an effective treatment option for opioid dependence, the individual and program-related factors that limit its effectiveness must be addressed to maximize the public health impact of this treatment.

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