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UBC Theses and Dissertations

Processes and patterns of cocaine use among patients receiving injectable opioids for the treatment of opioid use disorder : a multi-method study Palis, Heather Nadine


Background: Injectable opioid agonist treatment with hydromorphone (a licensed opioid analgesic) or diacetylmorphine (pharmaceutical grade heroin) is effective at reducing illicit opioid use and improving health and social functioning among patients with opioid use disorder. Concurrent cocaine use is prevalent among patients receiving injectable opioid agonist treatment, however modest declines have been observed in the proportion of patients using cocaine and in the number of days of cocaine use while engaged in treatment. To date, studies have not explored what processes might explain these reductions, or how patterns of cocaine use might vary over time at the intra- and inter-individual levels. Methods: This study was conducted with patients receiving daily injectable hydromorphone or diacetylmorphine for the treatment of opioid use disorder at a clinic in Vancouver, Canada. The qualitative analysis was guided by a grounded theory approach involving one-on-one patient interviews (n=31). Findings directed covariate selection for the quantitative analysis. The profile of participants using cocaine was characterized (n=166), and multilevel models were used to explain variation in cocaine use over 24-months, using data from a baseline visit and six follow-up visits. Results: Qualitative analysis revealed that access to injectable opioid agonist treatment promoted the self-management of cocaine use. Participants distanced themselves from the street environment, made efforts to “control” their cocaine use, and sought supports to bolster these efforts. Quantitative analyses identified significant intra- and inter-individual variation in cocaine use over 24-months. On average, cocaine use decreased over time, however the rate of change varied from one participant to the next. Women reported more cocaine use than men, and participants with more lifetime years of cocaine use at baseline reported more cocaine use over 24-months. Conclusions: This research highlights heterogeneity in patterns and processes of cocaine use. Intra- and inter-individual variation in cocaine use was identified, and was explained by participant characteristics, including demographics and substance use histories. Given daily contact with care, injectable opioid agonist treatment serves as an optimal setting to integrate treatments for cocaine use disorder. Care providers can communicate with patients about their patterns of cocaine use and associated characteristics to guide treatment plans.

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