Managing emergency department patients with opioid use disorder.

As the United States continues to grapple with the opioid crisis, emergency clinicians are on the front lines of managing patients with opioid use disorder. This issue reviews tools and best practices in emergency department management of patients with opioid overdose and opioid withdrawal, and how substance use history will inform treatment planning and disposition. As growing evidence shows that medications for opioid use disorder (MOUD)- buprenorphine, methadone, and naltrexone-can have lasting impacts on patients' addiction recovery, strategies for assessing patient readiness for MOUD and overcoming barriers to emergency department initiation of these medications are reviewed. Newer approaches to buprenorphine dosing (high-dose, low-dose, home induction, and long-acting injectable dosing) are also reviewed.

Harm Reduction for Opioid Use Disorder: Strategies and Outcome Metrics.

Tweet: The authors discuss harm reduction strategies and associated outcome metrics in relation to the ongoing opioid crisis.

Opioid Coprescription Through Risk Mitigation Guidance and Opioid Agonist Treatment Receipt.

Importance: At the onset of the COVID-19 pandemic, the government of British Columbia, Canada, released clinical guidance to support physicians and nurse practitioners in prescribing pharmaceutical alternatives to the toxic drug supply. These alternatives included opioids and other medications under the risk mitigation guidance (RMG), a limited form of prescribed safer supply, designed to reduce the risk of SARS-CoV-2 infection and harms associated with illicit drug use. Many clinicians chose to coprescribe opioid medications under RMG alongside opioid agonist treatment (OAT). Objective: To examine whether prescription of hydromorphone tablets or sustained-release oral morphine (opioid RMG) and OAT coprescription compared with OAT alone is associated with subsequent OAT receipt. Design, Setting, and Participants: This population-based, retrospective cohort study was conducted from March 27, 2020, to August 31, 2021, included individuals from 10 linked health administrative databases from British Columbia, Canada. Individuals who were receiving OAT at opioid RMG initiation and individuals who were receiving OAT and eligible but unexposed to opioid RMG were propensity score matched at opioid RMG initiation on sociodemographic and clinical variables. Data were analyzed between January 2023 and February 2024. Exposure: Opioid RMG receipt (≥4 days, 1-3 days, or 0 days of opioid RMG dispensed) in a given week. Main Outcome and Measures: The main outcome was OAT receipt, defined as at least 1 dispensed dose of OAT in the subsequent week. A marginal structural modeling approach was used to control for potential time-varying confounding. Results: A total of 4636 individuals (2955 [64%] male; median age, 38 [31-47] years after matching) were receiving OAT at the time of first opioid RMG dispensation (2281 receiving ongoing OAT and 2352 initiating RMG and OAT concurrently). Opioid RMG receipt of 1 to 3 days in a given week increased the probability of OAT receipt by 27% in the subsequent week (adjusted risk ratio, 1.27; 95% CI, 1.25-1.30), whereas receipt of opioid RMG for 4 days or more resulted in a 46% increase in the probability of OAT receipt in the subsequent week (adjusted risk ratio, 1.46; 95% CI, 1.43-1.49) compared with those not receiving opioid RMG. The biological gradient was robust to different exposure classifications, and the association was stronger among those initiating opioid RMG and OAT concurrently. Conclusions and Relevance: This cohort study, which acknowledged the intermittent use of both medications, demonstrated that individuals who were coprescribed opioid RMG had higher adjusted probability of continued OAT receipt or reengagement compared with those not receiving opioid RMG.

Retention of people who inject drugs enrolled in a 'medications for opioid use disorder' (MOUD) programme in Uganda.

BACKGROUND: Injection Drug use is associated with increased HIV risk behaviour that may result in the transmission of HIV and poor access to HIV prevention and treatment. In 2020, Uganda introduced the 'medication for opioid use disorder (MOUD) treatment' for People who inject drugs (PWID). We analysed the 12-month retention and associated factors among PWID enrolled on MOUD treatment in Kampala, Uganda. METHODS: We conducted a retrospective analysis of 343 PWID with OUD who completed 14 days of methadone induction from September 2020 to July 2022. Retention was defined as the number of individuals still in the programme divided by the total number enrolled, computed at 3-, 6-, 9-, and 12 months using lifetable and Kaplan-Meier survival analyses. Cox proportional regression analyses were conducted to assess factors associated with retention in the programme in the first 12 months. RESULTS: Overall, 243 (71%) of 343 participants stabilized at a methadone dose of 60 mg or more. The majority of participants were males (n = 284, 82.8%), and the median (interquartile range, IQR) age was 31 (26-38) years. Most participants (n = 276, 80.5%) lived 5 km or more away from the MOUD clinic. Thirty (8.8%) were HIV-positive, 52 (15.7%) had a major mental illness and 96 (27.9%) had a history of taking alcohol three months before enrollment. The cumulative retention significantly declined from 83.4% (95%CI = 79.0-87.0) at 3months to 71.9% (95%CI = 67.2-76.6) at 6months, 64% 95%CI = 58.7-68.9) at 9months, and 55.2%; 95% CI (49.8-60.3% at 12months. The 12-month retention was significantly higher for participants on methadone doses of 60 mg or more (adj.HR = 2.1, 95%CI = 1.41-3.22), while participants resident within 5 km of the MOUD clinic were 4.9 times more likely to be retained at 12 months, compared to those residing 5 km or more, (adj. HR = 4.81, 95%CI = 1.54-15). Other factors, including predisposing, need, and enabling factors, were not associated with retention. CONCLUSION: Our study demonstrates acceptable 12-month retention rates for people who inject drugs, comparable to previous studies done in both developing and developed countries. Sustaining and improving retention may require enhanced scaling up of MOUD dose to an optimal level in the first 14 days and reducing the distance between participant locale and MOUD clinics.

Mediating effect of craving on the impact of buprenorphine/naloxone and methadone treatment on opioid use: Results from a randomized controlled trial.

BACKGROUND: The relationship between opioid craving and opioid use is unclear. We sought to determine to what extent craving mediated the relationship between opioid agonist therapy and changes in opioid use. METHODS: Data came from a pragmatic, 24-week, pan-Canadian, multi-centric, open-label, randomized controlled trial comparing flexible buprenorphine/naloxone take-home doses to standard supervised methadone models of care for the treatment of prescription-type opioid use disorder. Participants were randomly allocated to buprenorphine/naloxone or methadone models of care. 270 people with prescription-type opioid use disorder were included in analyses. There were 93 women (34.4%) and 2 transgender (0.7%) participants. Most participants were white (67.4%), 45.9% reported unstable living conditions, and 44.8% had psychiatric comorbidities. Generalized linear mixed models followed by mediation analysis estimated the direct effect of treatment group on Timeline Followback-reported next-week opioid use and the indirect effect through past 24-hour opioid craving measured using the Brief Substance Craving Scale at week 2, 6, 10, 14, 18 and 22. RESULTS: Upon mediation analysis, the average direct effect of treatment on opioid use was 0.465 (95 % CI = 0.183 to 0.751, p < 0.001). The average causal mediated effect was 0.144 (95 % CI = 0.021 to 0.110; p < 0.001). Craving accounted for 23.6 % of the effect of treatment on opioid use (p < 0.001). CONCLUSIONS: Past 24-hour craving was associated with increased next-week opioid use; however, craving only partially mediated the effect of buprenorphine/naloxone and methadone on next-week opioid use. Research is needed to develop a comprehensive understanding of factors mediating opioid use during opioid agonist therapy.

Patients' perspectives on buprenorphine subcutaneous implant: a case series.

BACKGROUND: Considering the enormous burden represented by the opioid use disorder (OUD), it is important to always consider, when implementing opioid agonist therapy (OAT), the potential impact on patient's adherence, quality of life, and detoxification. Thus, the purpose of the study is to evaluate how the introduction of a novel OAT approach influences these key factors in the management of OUD. CASE PRESENTATION: This article marks the pioneering use of OAT through buprenorphine implant in Europe and delves into the experience of six patients diagnosed with OUD at a relatively young age. The patients, comprising both males and a female, are of Caucasian Italian and African Italian ancestry (case 4) and exhibit an age range from 23 to 63, with an average drug abuse history of 19 ± 12 years. All patients were on stable traditional OAT before transitioning to buprenorphine implants. Despite the heterogeneity in social and educational backgrounds, health status, and drug abuse initiation histories, the case series reveals consistent positive treatment outcomes such as detoxification, absence of withdrawal symptoms and of side effects. Notably, all patients reported experiencing a newfound sense of freedom and improved quality of life. CONCLUSIONS: These results emphasise the promising impact of OAT via buprenorphine implants in enhancing the well-being and quality of life in the context of OUD.

"It didn't hurt me": patients' and providers' perspectives on unsupervised take-home doses, drug diversion, and overdose risks in the provision of medication for opioid use disorder during COVID-19 in San Juan, Puerto Rico.

BACKGROUND: During the COVID-19 pandemic, clinics offering medication for opioid use disorder (MOUD) needed to rapidly introduce unsupervised take-home dosing, while relapsing patients and patients unable to enter treatment faced increased risks of fentanyl-related overdose deaths and other drug-related harms. Based on a qualitative study of people who inject drugs (PWID) receiving MOUD treatment and MOUD staff in Puerto Rico, this paper documents the lived experiences of patients and providers during this period and the risk perceptions and management strategies to address substance misuse and drug diversion attributable to unsupervised take-home-dose delivery. METHODS: In-depth qualitative interviews were conducted with patients (N = 25) and staff (N = 25) in two clinics providing MOUD in San Juan, Puerto Rico, during 2022. Patients and staff were receiving or providing treatment during the pandemic, and patients reported injection drug use during the past thirty days. RESULTS: Patients were overwhelmingly male (84%), unmarried (72%), and unemployed (52%), with almost half (44%) injecting one to three times a day. Mean time in treatment was 7 years. Staff had a mean age of 46 years with more than half of the sample (63%) female. The majority of patients believed that unsupervised take-home dosing had no significant effect on their treatment adherence or engagement. In contrast, providers expressed concerns over the potential for drug diversion and possible increased risks of patient attrition, overdose episodes, and poor treatment outcomes. CONCLUSION: This study underscores the importance of insider perspectives on harm-reduction changes in policy implemented during a health crisis. Of note is the finding that staff disagreed among themselves regarding the potential harms of diversion and changes in drug testing protocols. These different perspectives are important to address so that future pandemic policies are successfully designed and implemented. Our study also illuminates disagreement in risk assessments between patients and providers. This suggests that preparation for emergency treatment plans requires enhanced communication with patients to match treatments to the context of lived experience.

Assessing fragility of statistically significant findings from randomized controlled trials assessing pharmacological therapies for opioid use disorders: a systematic review.

BACKGROUND: The fragility index is a statistical measure of the robustness or "stability" of a statistically significant result. It has been adapted to assess the robustness of statistically significant outcomes from randomized controlled trials. By hypothetically switching some non-responders to responders, for instance, this metric measures how many individuals would need to have responded for a statistically significant finding to become non-statistically significant. The purpose of this study is to assess the fragility index of randomized controlled trials evaluating opioid substitution and antagonist therapies for opioid use disorder. This will provide an indication as to the robustness of trials in the field and the confidence that should be placed in the trials' outcomes, potentially identifying ways to improve clinical research in the field. This is especially important as opioid use disorder has become a global epidemic, and the incidence of opioid related fatalities have climbed 500% in the past two decades. METHODS: Six databases were searched from inception to September 25, 2021, for randomized controlled trials evaluating opioid substitution and antagonist therapies for opioid use disorder, and meeting the necessary requirements for fragility index calculation. Specifically, we included all parallel arm or two-by-two factorial design RCTs that assessed the effectiveness of any opioid substitution and antagonist therapies using a binary primary outcome and reported a statistically significant result. The fragility index of each study was calculated using methods described by Walsh and colleagues. The risk of bias of included studies was assessed using the Revised Cochrane Risk of Bias tool for randomized trials. RESULTS: Ten studies with a median sample size of 82.5 (interquartile range (IQR) 58, 179, range 52-226) were eligible for inclusion. Overall risk of bias was deemed to be low in seven studies, have some concerns in two studies, and be high in one study. The median fragility index was 7.5 (IQR 4, 12, range 1-26). CONCLUSIONS: Our results suggest that approximately eight participants are needed to overturn the conclusions of the majority of trials in opioid use disorder. Future work should focus on maximizing transparency in reporting of study results, by reporting confidence intervals, fragility indexes, and emphasizing the clinical relevance of findings. TRIAL REGISTRATION: PROSPERO CRD42013006507. Registered on November 25, 2013.

Changes in Buprenorphine Prescribing in Community Health Centers.

This cohort study characterizes changes in buprenorphine prescribing among community health center clinicians between 2016 and 2021.

Integrated Hepatitis C-Opioid Use Disorder Care Through Facilitated Telemedicine: A Randomized Trial.

Importance: Facilitated telemedicine may promote hepatitis C virus elimination by mitigating geographic and temporal barriers. Objective: To compare sustained virologic responses for hepatitis C virus among persons with opioid use disorder treated through facilitated telemedicine integrated into opioid treatment programs compared with off-site hepatitis specialist referral. Design, Setting, and Participants: Prospective, cluster randomized clinical trial using a stepped wedge design. Twelve programs throughout New York State included hepatitis C-infected participants (n = 602) enrolled between March 1, 2017, and February 29, 2020. Data were analyzed from December 1, 2022, through September 1, 2023. Intervention: Hepatitis C treatment with direct-acting antivirals through comanagement with a hepatitis specialist either through facilitated telemedicine integrated into opioid treatment programs (n = 290) or standard-of-care off-site referral (n = 312). Main Outcomes and Measures: The primary outcome was hepatitis C virus cure. Twelve programs began with off-site referral, and every 9 months, 4 randomly selected sites transitioned to facilitated telemedicine during 3 steps without participant crossover. Participants completed 2-year follow-up for reinfection assessment. Inclusion criteria required 6-month enrollment in opioid treatment and insurance coverage of hepatitis C medications. Generalized linear mixed-effects models were used to test for the intervention effect, adjusted for time, clustering, and effect modification in individual-based intention-to-treat analysis. Results: Among 602 participants, 369 were male (61.3%); 296 (49.2%) were American Indian or Alaska Native, Asian, Black or African American, multiracial, or other (ie, no race category was selected, with race data collected according to the 5 standard National Institutes of Health categories); and 306 (50.8%) were White. The mean (SD) age of the enrolled participants in the telemedicine group was 47.1 (13.1) years; that of the referral group was 48.9 (12.8) years. In telemedicine, 268 of 290 participants (92.4%) initiated treatment compared with 126 of 312 participants (40.4%) in referral. Intention-to-treat cure percentages were 90.3% (262 of 290) in telemedicine and 39.4% (123 of 312) in referral, with an estimated logarithmic odds ratio of the study group effect of 2.9 (95% CI, 2.0-3.5; P < .001) with no effect modification. Observed cure percentages were 246 of 290 participants (84.8%) in telemedicine vs 106 of 312 participants (34.0%) in referral. Subgroup effects were not significant, including fibrosis stage, urban or rural participant residence location, or mental health (anxiety or depression) comorbid conditions. Illicit drug use decreased significantly (referral: 95% CI, 1.2-4.8; P = .001; telemedicine: 95% CI, 0.3-1.0; P < .001) among cured participants. Minimal reinfections (n = 13) occurred, with hepatitis C virus reinfection incidence of 2.5 per 100 person-years. Participants in both groups rated health care delivery satisfaction as high or very high. Conclusions and Relevance: Opioid treatment program-integrated facilitated telemedicine resulted in significantly higher hepatitis C virus cure rates compared with off-site referral, with high participant satisfaction. Illicit drug use declined significantly among cured participants with minimal reinfections. Trial Registration: ClinicalTrials.gov Identifier: NCT02933970.

Methadone dosing at New York State opioid treatment programs following initial revisions to federal regulations.

INTRODUCTION: In March 2020, a temporary federal regulatory exemption for opioid treatment programs (OTPs) was issued, allowing for a greater number of take-home methadone doses than was previously permitted. In the same month, to address financial sustainability, New York State (NYS) Medicaid also transitioned to a bundle reimbursement methodology for OTPs. We examined methadone dosing schedules in NYS before and after these regulatory and financing changes. METHODS: We conducted a retrospective cohort study using NYS OTP patient data from two sources: the client data system for a baseline period (February 2020) and survey data collected after regulatory and financing changes (May 2020 to August 2021, 64 weekly surveys). We compared methadone dosing schedules over time using chi-square tests and Poisson regression. RESULT: At baseline, data were available for 78% (n=77/99) of OTPs including 90.9% (n=26,225/28,839) of their enrolled patients. During the survey period, 99 OTPs completed 93.1% (n=5901/6336) of weekly surveys, with a mean statewide weekly patient census of 38,904 (SD=1214.5). Between February and May 2020, daily dosing significantly decreased from 55.4% to 16.3% of patients (-39.1 percentage points [95%CI: -39.8 to -38.4]), although it significantly increased subsequently (3.33%/4-weeks [95%CI: 3.28, 3.39]). In addition, weekly-to-monthly dosing significantly increased from 26.9% to 54.5% of patients (27.6 percentage points [95%CI: 26.9, 28.4]), although it significantly decreased subsequently (-1.19%/4-weeks [95%CI: -1.23, -1.15]). DISCUSSION: Despite large initial changes, we found a trend toward gradual return to more restrictive dosing schedules. OTPs need further support in leveraging new opportunities to improve methadone treatment and outcomes.

Extended-release versus oral buprenorphine as opioid maintenance treatment during pregnancy-maternal and neonatal outcomes.

OBJECTIVE: To get information on subcutaneous extended-release buprenorphine as opioid maintenance treatment during pregnancy, we compared it to orally administered buprenorphine and buprenorphine-naloxone treatments. We hypothesized that maternal and neonatal outcomes do not differ between the treatment groups. Study design In this population-based cohort study, 60 pregnant individuals receiving non-changed opioid maintenance treatment for opioid use disorder with a buprenorphine product from the time before conception to the time after delivery and their newborns were included. They were divided into three groups based on the pharmacotherapy with subcutaneous extended-release buprenorphine, sublingual buprenorphine, or buprenorphine-naloxone. Statistical analyses were conducted using Fischer's exact tests, ANOVA tests, and Kruskal-Wallis tests. All the statistical tests were two-tailed. RESULTS: The frequency of pregnancy or delivery complications did not significantly differ between the group receiving extended-release buprenorphine and the other groups. During pregnancy, 38 % of the women used illicit drugs concomitantly, with equal frequency in the extended-release buprenorphine group and the other groups. Of the neonates, 93 % were born full-term and 90 % got at least eight Apgar points in one minute age, without significant differences between the groups (p = 0.57). The need for pharmacotherapy for neonatal opioid withdrawal syndrome was the lowest in the extended-release buprenorphine group (25 %) and highest in the sublingual buprenorphine group (67 %). Still, the difference between the treatment groups did not reach statistical significance (p = 0.17). Among all neonates, the breastfed infants were less likely to receive pharmacotherapy for withdrawal symptoms than the formula-fed ones (p = 0.048). CONCLUSIONS: Extended-release buprenorphine with steady drug concentration seems to be a promising pharmacotherapy option during pregnancy for mothers. Maternal health during pregnancy may contribute to the well-being of newborns. Larger trials are urgently needed to confirm these results..

High-Dose Buprenorphine Initiation in the Management of Opioid Use Disorder in Pregnancy.

Buprenorphine is commonly used as a treatment for opioid use disorder (OUD). Transition to buprenorphine traditionally has been done using a low-dose initiation regimen due to concerns surrounding precipitated withdrawal. There are increasing data supporting use of a high-dose initiation regimen in the nonpregnant population. This retrospective case series describes six individuals with OUD who underwent high-dose buprenorphine initiation in pregnancy. There were no instances of sedation, respiratory depression, supplemental oxygen use, or death. All individuals were successfully transitioned to buprenorphine. These findings provide support for high-dose buprenorphine initiation in pregnancy, but future large studies are needed.

What is the ideal time to begin tapering opioid agonist treatment? A protocol for a retrospective population-based comparative effectiveness study in British Columbia, Canada.

INTRODUCTION: Opioid agonist treatment (OAT) tapering involves a gradual reduction in daily medication dose to ultimately reach a state of opioid abstinence. Due to the high risk of relapse and overdose after tapering, this practice is not recommended by clinical guidelines, however, clients may still request to taper off medication. The ideal time to initiate an OAT taper is not known. However, ethically, taper plans should acknowledge clients' preferences and autonomy but apply principles of shared informed decision-making regarding safety and efficacy. Linked population-level data capturing real-world tapering practices provide a valuable opportunity to improve existing evidence on when to contemplate starting an OAT taper. Our objective is to determine the comparative effectiveness of alternative times from OAT initiation at which a taper can be initiated, with a primary outcome of taper completion, as observed in clinical practice in British Columbia (BC), Canada. METHODS AND ANALYSIS: We propose a population-level retrospective observational study with a linkage of eight provincial health administrative databases in BC, Canada (01 January 2010 to 17 March 2020). Our primary outcomes include taper completion and all-cause mortality during treatment. We propose a 'per-protocol' target trial to compare different durations to taper initiation on the likelihood of taper completion. A range of sensitivity analyses will be used to assess the heterogeneity and robustness of the results including assessment of effectiveness and safety. ETHICS AND DISSEMINATION: The protocol, cohort creation and analysis plan have been classified and approved as a quality improvement initiative by Providence Health Care Research Ethics Board and the Simon Fraser University Office of Research Ethics. Results will be disseminated to local advocacy groups and decision-makers, national and international clinical guideline developers, presented at international conferences and published in peer-reviewed journals electronically and in print.

Long-acting injectable depot buprenorphine from a harm reduction perspective in patients with ongoing substance use and multiple psychiatric comorbidities: a qualitative interview study.

BACKGROUND: Long-acting injectable depot buprenorphine may increase access to opioid agonist treatment (OAT) for patients with opioid use disorder in different treatment phases. The aim of this study was to explore the experiences of depot buprenorphine among Swedish patients with ongoing substance use and multiple psychiatric comorbidities. METHOD: Semi-structured qualitative interviews were conducted with OAT patients with experience of depot buprenorphine. Recruitment took place at two OAT clinics with a harm reduction focus, specializing in the treatment of patients with ongoing substance use and multiple comorbidities. Nineteen participants were included, 12 men and seven women, with a mean age of 41 years (range 24-56 years), and a mean of 21 years (5-35 years) of experience with illicit substance use. All participants had ongoing substance use and psychiatric comorbidities such as ADHD, anxiety, mood, psychotic and eating disorders. Interviews were transcribed verbatim. Thematic content analysis was conducted both manually and using qualitative data analysis software. RESULTS: Participants reported social benefits and positive changes in self-perception and identity. In particular, depot buprenorphine contributed to a realization that it was possible to make life changes and engage in activities not related to substance use. Another positive aspect that emerged from the interviews was a noticeable relief from perceived pressure to divert OAT medication, while some expressed the lack of income from diverted oral/sublingual OAT medication as a negative, but still acceptable, consequence of the depot buprenorphine. Many participants considered that the information provided prior to starting depot buprenorphine was insufficient. Also, not all patients found depot buprenorphine suitable, and those who experienced coercion exhibited particularly negative attitudes towards the medication. CONCLUSIONS: OAT patients with ongoing substance use and multiple psychiatric comorbidities reported clear benefits of depot buprenorphine, including changes in self-perception which has been theorized to play an important role in recovery. Clinicians should consider the specific information needs of this population and the extensive diversion of traditional OAT medications in this population to improve the treatment experience and outcomes. Overall, depot buprenorphine is a valuable treatment option for a population in need of harm reduction and may also contribute to psychological changes that may facilitate recovery in those with the greatest need.

Network Analysis of Medical Claims Data Suggests Network-Based, Regional Targeting and Intervention Delivery Strategies to Increase Access to Office Based Opioid Treatment (OBOT) for Opioid Use Disorder (OUD).

Opioid overdose and Opioid Use Disorder (OUD) statistics underscore an urgent need to significantly expand access to evidence-based OUD treatment. Office Based Opioid Treatment (OBOT) has proven effective for treating OUD. However, limited access to these treatments persists. Recognizing the need for significant investment in clinical, behavioral, and translational research, the Indiana State Department of Health and Indiana University embarked on a research initiative supported by the "Responding to the Addictions Crisis" Grand Challenge Program. This brief presents recommendations based on existing research and our own analyses of medical claims data in Indiana, where opioid misuse is high and treatment access is limited. The recommendations cover target providers, intervention focus, priority regions, and delivery methods.

A population-based time-series analysis of opioid agonist treatment dispensed during pregnancy.

BACKGROUND AND AIMS: Identifying effective opioid treatment options during pregnancy is a high priority due to the growing prevalence of opioid use disorder across North America. We assessed the temporal impact of three population-level interventions on the use of opioid agonist treatment (OAT) during pregnancy in Ontario, Canada. DESIGN: This was a population-based time-series analysis to identify trends in the monthly prevalence of pregnant people dispensed methadone and buprenorphine. The impact of adding buprenorphine/naloxone to the public drug formulary, the release of pregnancy-specific guidance and the start of the COVID-19 pandemic were assessed. SETTING AND PARTICIPANTS: The study was conducted in Ontario, Canada between 1 July 2013 and 31 March 2022, comprising people who delivered a live or stillbirth in any Ontario hospital during the study period. MEASUREMENTS: We identified any prescription for methadone or buprenorphine dispensed between the estimated conception date and delivery date and calculated the monthly prevalence of OAT-exposed pregnancies among all pregnant people in Ontario. FINDINGS: Overall, rates of OAT during pregnancy have declined since mid-2018. Methadone-exposed pregnancies decreased from 0.46% of all pregnancies in Ontario in 2015 to a low of 0.16% in 2022. In the primary analysis, none of the interventions had a statistically significant impact on overall OAT rates; however, in the stratified analyses, there was a small increase in buprenorphine after the formulary change [0.006%, 95% confidence interval (CI) = 0.0032-0.0081, P < 0.0001] and a decrease in buprenorphine after the release of the 2017 guidelines (-0.005%, 95% CI = -0.0080 to -0.0020, P = 0.001) and the start of the COVID-19 pandemic (-0.003%, 95% CI = -0.0054 to -0.0006, P = 0.015). CONCLUSION: Despite changes in guidance and funding, opioid agonist treatment during pregnancy has been declining in Ontario, Canada since 2018.