Evaluating a novel pharmacist-led buprenorphine outreach service for treatment of opioid use disorder in individuals residing in supportive housing

Authors: Janice Ly Pharm.D., Damian Peterson Pharm.D., Michelle Geier Pharm.D.

Journal: Journal of the American College of Clinical Pharmacy, 2024; Volume 7, Issue 2, Pages 115–122

Type of Study: 3-month pre-and-post interventional pilot study

DOI: 10.1002/jac5.1915

Quick Reference Summary

A pharmacist-led buprenorphine (BUP) outreach service significantly increased treatment adherence among individuals residing in permanent supportive housing (PSH), with adherence rates rising from 3% pre-intervention to 37% post-intervention (p = 0.0009). Additionally, the mean prescription days covered (PDC) improved from 8% before the intervention to 58% after (p < 0.00001), indicating enhanced engagement with BUP treatment.

Core Clinical Question

Does a pharmacist-led buprenorphine outreach service improve treatment adherence in individuals with opioid use disorder residing in permanent supportive housing compared to standard care?

Background

Disease Overview

Opioid Use Disorder (OUD) is a chronic condition characterized by the misuse of opioid substances, leading to significant morbidity and mortality. In 2022, San Francisco reported 638 accidental overdose deaths involving opioids, disproportionately affecting the Black population and those with fixed housing.

Prior Data

• Low-barrier buprenorphine (BUP) treatment models have shown improved engagement and retention in care among marginalized populations experiencing houselessness (PEH).
• Only 20% of individuals with OUD receive treatment, despite evidence-based medications like methadone and BUP reducing overdose risk by over 50%.

Current Standard of Care

Evidence-based treatments for OUD, including methadone and buprenorphine, are available but underutilized due to barriers such as stigma, logistical issues, and lack of knowledge about OUD and treatments.

Knowledge Gaps Addressed by Study

Limited data on the effectiveness of low-barrier BUP treatment models among individuals residing in permanent supportive housing (PSH).

Study Rationale

Given the high rate of opioid overdose deaths among individuals with fixed housing and the potential for low-barrier models to improve treatment engagement, this study aims to evaluate a pharmacist-led BUP outreach service to enhance adherence and address socioeconomic and racial disparities in OUD treatment.

Methods Summary

Study Design

3-month pre-and-post interventional pilot study.

Setting and Time Period

Conducted in San Francisco through the Permanent Housing Advanced Clinical Services (PHACS) Team from August 10, 2022, through November 2, 2022.

Population Characteristics

• Number of Participants: 38 individuals enrolled.
• Mean Age: 46 years.
• Race: 42% Black, 34% White, 18% Latin or Hispanic, 6% Other.
• Gender Identity: 76% Male, 18% Female, 6% Other.

Inclusion/Exclusion Criteria

• Inclusion: Adults aged 18 or older, residing in PSH, meeting DSM 5-TR criteria for OUD.
• Exclusion: Patients without a documented OUD diagnosis were not required to see a diagnosing provider prior to pharmacist engagement.

Intervention Details

• Pharmacist-Led Outreach: A board-certified psychiatric pharmacist conducted intake interviews, provided same-day BUP prescriptions, extensive counseling, and initiated psychiatric medications as appropriate.
• BUP Initiation Methods:
  • Traditional Initiation: Required opioid cessation and withdrawal symptoms before starting BUP.
  • 7-Day Low-Dose Overlap Initiation (LDOI): No need for opioid cessation; gradual BUP dose increase over 7 days.
  • 3-Day Rapid LDOI: Similar to 7-day but with quicker titration.
• Adjunctive Medications: Ondansetron, clonidine, lorazepam, and trazodone based on withdrawal symptoms.
• Harm Reduction Supplies: Naloxone nasal spray, syringes, sterile water, alcohol swabs, cookers, and fentanyl test strips.

Control/Comparison Group Details

Pre-intervention adherence rates were compared to post-intervention rates within the same population.

Primary and Secondary Outcomes

• Primary Outcome: Treatment adherence, defined as ≥80% prescription days covered (PDC) over 3 months.
• Secondary Outcomes: Change in PDC, linkage to office-based care, incidence of overdose, emergency department (ED) presentations, hospital admissions, and successful BUP initiation.

Statistical Analysis Approach

• Analyses Included: All enrolled participants.
• Categorical Data: Described using counts and percentages; analyzed using McNemar's test.
• Continuous Data: Described using means and standard deviations; analyzed using paired t-test.
• Significance Level: p < 0.05.

Sample Size Calculations

Not explicitly stated; pilot study nature implies exploratory analysis.

Ethics and Funding Information

• Ethics: Deemed exempt by the University of California, San Francisco (UCSF) Institutional Review Board.
• Funding: No external funding.

Detailed Results

Participant Flow and Demographics

• Total Enrolled: 38 patients.
• Age: Mean age of 46 years.
• Race: 42% Black, 34% White, 18% Latin or Hispanic, 6% Other.
• Gender Identity: 76% Male, 18% Female, 6% Other.
• Preferred Opioid at BUP Initiation: 61% Fentanyl, 32% Heroin, 61% Fentanyl, 8% Methadone, 5% Other.
• Past MOUD Trials: 68% Buprenorphine, 45% Methadone.
• Other Substance Use: 66% reported stimulant use.
• Comorbid Mental Health Conditions: 42% diagnosed.

Primary Outcome Results

• Pre-Intervention ≥80% PDC: 3% (1 patient).
• Post-Intervention ≥80% PDC: 37% (14 patients).
• Statistical Significance: p = 0.0009.
• Mean PDC: Increased from 8% (SD = 22%) pre-intervention to 58% (SD = 36%) post-intervention (p < 0.00001).

Secondary Outcome Results

• Successful Initiation of BUP: 83% (30 patients).
• Linkage to Office-Based Care: 2.6% (1 patient).
• Transition from Methadone to BUP: 7.9% (3 patients).
• Emergency Department (ED) Presentations: Decreased from 16% pre-intervention to 3% post-intervention (p = 0.28).
• Hospital Admissions: Increased from 0% pre-intervention to 3% post-intervention (p = 1).
• Overdose Incidence: Decreased from 3% pre-intervention to 0% post-intervention.

Subgroup Analyses

• Transitioned to Injectable BUP Extended-Release: 2.6% (1 patient).
• Urine Drug Screens (UDS):
  • BUP Positive: 33%.
  • Opioid Negative: 100% (3 patients).

Adverse Events/Safety Data

No significant change in overdose incidence or hospital admissions reported post-intervention.

Results Tables

*Percentage based on 36 new BUP initiations.

Authors' Conclusions

The study concluded that a novel pharmacist-led buprenorphine outreach service effectively increased treatment adherence among individuals residing in PSH over a 3-month period. The authors interpret these findings as evidence that low-barrier BUP treatment models can provide more equitable and accessible care, thereby addressing socioeconomic and racial disparities in opioid overdose deaths. They recommend that such models be considered for broader implementation to enhance medication adherence and support marginalized populations.

Literature Review

• Comparative Analysis: The study's adherence rate of 37% at 3 months is lower than a larger-scale 2018 study which reported 37.1% and 41.3% at 12 months for commercial and Medicaid patients, respectively. However, differences in study populations and timeframes limit direct comparisons.
• Race and Treatment Rates: The intervention successfully engaged 42% Black patients, aligning with the higher overdose death rates in this demographic compared to existing treatment disparities where Black individuals receive lower rates of substance use services.
• Harm Reduction Approaches: Previous literature has emphasized the effectiveness of low-barrier models in PEH, but this study extends those findings to individuals in PSH, a population with stable housing yet high overdose risks due to residential relocations.

Detailed on Literature Context

A. Previous Studies and Meta-Analyses:

1. Biondi et al., 2020: Examined primary outcomes of medication treatment studies for OUD, discussing appropriate measures for treatment success.
   Am J Addict. 2020;29(4):249–267.
2. Ly et al., 2018: Analyzed prescription drug monitoring data in Philadelphia, finding that individuals in PSH had lower PDC compared to broader populations.
   Addiction. 2018;117(12):3079–3088.
3. Carter et al., 2019: Studied low barrier buprenorphine treatment for persons experiencing homelessness in San Francisco, demonstrating increased access and retention.
   Addict Sci Clin Pract. 2019;14(1):20.
4. Jakubowski & Fox, 2020: Defined low-threshold buprenorphine treatment and its implications for enhancing treatment accessibility.
   J Addict Med. 2020;14(2):95–98.

B. Contrasting Methodological Quality:

Ly et al. vs. Larger-Scale Studies: While Ly et al.'s pilot study showed significant improvements in PDC over a short duration, larger-scale studies with longer follow-up periods may provide more robust evidence but were not directly compared in the current study.

C. Comparisons with Guidelines:

Pharmacy Quality Alliance (PQA), 2022: Recommends PDC as a standard measure for adherence in chronic drug therapies.

D. This Trial's Contribution:

Extension to PSH Population: This study adds to the literature by demonstrating the effectiveness of a pharmacist-led BUP outreach service specifically in the PSH population, a group with stable housing yet high overdose risks due to residential relocations, thereby addressing a previously underexplored demographic in OUD treatment research.

Critical Analysis

A. Strengths

Methodological Strengths:

• Pre-and-Post Design: Allowed for direct comparison within the same population.
• Low-Barrier Intervention: Facilitated easier access to BUP, potentially enhancing engagement.
• Multidisciplinary Approach: Integration of pharmacists within the PHACS team improved comprehensive care.

Internal Validity Considerations:

• Consistent Measurement: Use of PDC as a standard adherence metric.
• Statistical Significance: Strong p-values indicating reliable results.

External Validity Considerations:

• Demographic Representation: Inclusion of a significant proportion of Black patients aligns with overdose demographics in PSH.
• Real-World Setting: Implementation within existing PSH structures increases generalizability to similar settings.

B. Limitations

Study Design Limitations:

• Pre-and-Post Without Control: Limits ability to attribute changes solely to the intervention.

Potential Biases:

• Selection Bias: Enrollment via outreach events, self-referral, and case management referrals may not capture all eligible individuals.

Generalizability Issues:

• Single Location: Conducted in San Francisco, findings may not be applicable to other regions with different demographics or PSH structures.

Statistical Limitations:

• Small Sample Size: Pilot nature with 38 participants may affect the power and robustness of findings.

Missing Data Handling:

• Limited UDS Data: Unable to confirm periods of adherence without comprehensive UDS, potentially affecting outcome accuracy.

Clinical Application

The findings suggest that implementing a pharmacist-led buprenorphine outreach service in permanent supportive housing can substantially enhance treatment adherence for individuals with opioid use disorder. This model is particularly applicable to marginalized populations within PSH settings, offering a low-barrier and accessible approach that integrates seamlessly with existing housing support services.

How To Use This Info In Practice: Clinicians and healthcare administrators should consider adopting pharmacist-led BUP outreach services in supportive housing environments to improve medication adherence and address opioid use disorder effectively.