Disruptions in Pharmacotherapy for Opioid Use Disorder Associated with Changes in Pharmacy

Date

2021-05

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Abstract

Introduction: Buprenorphine is a partial opioid agonist indicated for the treatment of opioid use disorder (OUD). Unlike methadone and naltrexone that may only be dispensed at outpatient treatment centers, a multiple day supply of buprenorphine may be dispensed at a community pharmacy pursuant to prescription from a Drug Addiction Treatment Act 2000 (DATA 2000) waivered prescriber. Outpatient treatment with buprenorphine was intended to improve access to medication for OUD (MOUD), this process of care, however, has been complicated by both geospatial and interpersonal barriers to access. One such barrier is that pharmacies are reluctant to stock buprenorphine and maintain patients on treatment leading many patients to change pharmacies, often early in treatment. The central objective of this dissertation is to determine if changes in pharmacy lead to disruptions in continuity of pharmacotherapy for opioid use disorder. In the third and final aim, we address another important question by examining how duration of treatment impacts the likelihood of initiating or returning to prescription opioid use after treatment discontinuation. While prescription opioid use after MOUD discontinuation represents an adverse treatment outcome, it may also represent a maladapted process. We, therefore, describe patterns of pharmacy and prescription monitoring program (PMP) utilization following treatment discontinuation in order to identify areas where increased pharmacy diligence is needed. Methods: Each of the objectives were evaluated in a cohort of incident buprenorphine users identified from the 2016-2018 Texas Prescription Monitoring Program prescription fill dataset. A change in pharmacy was defined by using two different pharmacies in two, subsequent buprenorphine dispensations. In the first aim, a repeated measures, generalized linear model was used to determine the association between a change in pharmacy and a concomitant gap in therapy. In the second, the Anderson Gill model for counting processes1 was used to determine if early changes in pharmacy were more likely to lead to gaps in therapy than changes in pharmacy later in therapy. In the final aim, patients who discontinued buprenorphine at least 180-days before December 31, 2018 were identified from the initial cohort. A Cox proportional hazard model stratified by prior prescription opioid use was then used to identify the association between duration of treatment with buprenorphine and time to initial opioid prescription. The pharmacy that filled each patient’s initial opioid prescription post-buprenorphine was identified and compared to the pharmacies where they filled buprenorphine. Whether or not each opioid prescription was queried in the PMP prior to dispensation was also identified. Results: Changes in pharmacy were associated with a significant increase in the odds of a gap in therapy of seven days or longer. The median time from the initiation of treatment to initial change in pharmacy was 30-days. Patients who changed pharmacies within thirty-days of treatment initiation were at a significantly higher risk of a gap in therapy compared to those who change later in therapy. Finally, patients treated for a longer duration were significantly less likely to fill an opioid prescription after treatment discontinuation. Over 1/3 of all patients who filled an opioid prescription after buprenorphine discontinuation did so at a pharmacy where they had previously filled buprenorphine and the PMP was used in 9.9% of cases prior to dispensation. Conclusions: Patients frequently change pharmacies during treatment with buprenorphine. When patients change, they are at risk of clinically meaningful gaps in therapy. This is especially true for early changes in pharmacy, a troubling finding given that the median time to initial change in pharmacy was 30-days. Another threat to the quality of pharmaceutical care for patients with OUD is pharmacists’ willingness to dispense opioid analgesics to patients who recently discontinued buprenorphine. The PMP should, ideally, prevent this, however, it remains an underutilized resource.

Description

Keywords

buprenorphine, pharmacy practice, opioid substitution treatment, health services research

Citation

Portions of this document appear in: Varisco, Tyler J., Susan Abughosh, Hua Chen, Sang Kyu Cho, Marc L. Fleming, Douglas Ziedonis, and Douglas Thornton. "Switching pharmacies leads to gaps in medication possession in individuals treated with buprenorphine." Journal of the American Pharmacists Association (2021).