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Use of other opioids during methadone therapy: a population-based study

Authors

  • Paul Kurdyak,

    Corresponding author
    1. Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada
    2. Centre for Addiction and Mental Health, Toronto, Ontario, Canada
    3. Department of Health Policy, Management and Evaluation, University of Toronto, Toronto, Ontario, Canada
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  • Tara Gomes,

    1. Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada
    2. Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
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  • Zhan Yao,

    1. Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada
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  • Muhammad M. Mamdani,

    1. Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada
    2. Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
    3. Department of Medicine, University of Toronto, Toronto, Ontario, Canada
    4. Department of Health Policy, Management and Evaluation, University of Toronto, Toronto, Ontario, Canada
    5. Keenan Research Centre of the Li Ka-Shing Knowledge Institute, St Michael's Hospital, Toronto, Ontario, Canada
    6. King Saud University, Riyadh, Saudi Arabia
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  • Chelsea Hellings,

    1. Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada
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  • Benedikt Fischer,

    1. Centre for Addiction and Mental Health, Toronto, Ontario, Canada
    2. Centre for Applied Research in Mental Health and Addictions, Faculty of Health Sciences, Simon Fraser University, Vancouver, BC, Canada
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  • Jürgen Rehm,

    1. Centre for Addiction and Mental Health, Toronto, Ontario, Canada
    2. Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada
    3. Department of Psychiatry, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
    4. Epidemiological Research Unit, Technische Universität Dresden, Klinische Psychologie and Psychotherapie, Dresden, Germany
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  • Ahmed M. Bayoumi,

    1. Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada
    2. Department of Medicine, University of Toronto, Toronto, Ontario, Canada
    3. Department of Health Policy, Management and Evaluation, University of Toronto, Toronto, Ontario, Canada
    4. Department of Medicine, St Michael's Hospital, Toronto, Ontario, Canada
    5. Keenan Research Centre of the Li Ka-Shing Knowledge Institute, St Michael's Hospital, Toronto, Ontario, Canada
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  • David N. Juurlink

    1. Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada
    2. Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
    3. Department of Medicine, University of Toronto, Toronto, Ontario, Canada
    4. Department of Pediatrics, University of Toronto, Toronto, Ontario, Canada
    5. Department of Health Policy, Management and Evaluation, University of Toronto, Toronto, Ontario, Canada
    6. Sunnybrook Research Institute, Toronto, Ontario, Canada
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Paul Kurdyak, Centre for Addiction and Mental Health, 250 College Street, Toronto, Ontario, Canada, M5T 1R8. E-mail: paul_kurdyak@camh.net

ABSTRACT

Aims  To determine the extent to which other opioids are prescribed to patients receiving methadone in Ontario, Canada.

Design  Retrospective cohort study.

Setting  Ontario, Canada from 1 April 2003 to 31 March 2010.

Participants  We studied patients aged 15–64 years with publically funded drug coverage who received at least 30 days of continuous methadone maintenance therapy (MMT).

Measurements  The proportion of patients who received more than 7 days of a non-methadone opioid during MMT. A secondary analysis examined the extent to which non-methadone opioids were prescribed by physicians or dispensed by pharmacies not involved in a patient's MMT.

Findings  Among 18 759 patients treated with methadone, 3456 (18.4%) received at least one prescription for non-methadone opioids of more than 7 days' duration. In this group, the median number of non-methadone opioid prescriptions dispensed per year was 11.9 (interquartile range 4.1–25.0). The most frequently prescribed opioids were codeine and oxycodone. Of the 73 520 non-methadone opioid prescriptions of more than 7 days' duration, nearly half (45.8%) originated from non-MMT prescribers and pharmacies.

Conclusions  Many patients receiving methadone maintenance therapy in Ontario receive overlapping prescriptions for other opioids, often for extended periods. The associated prescribing patterns suggest that many such prescriptions may be duplicitous. The prescribing and dispensing of non-methadone opioids to patients receiving methadone maintenance therapy is likely to be observed in jurisdictions outside Ontario, Canada.

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