Comparative Analysis of Instrumental Variables on the Assignment of Buprenorphine/Naloxone or Methadone for the Treatment of Opioid Use Disorder.

BACKGROUND: Instrumental variable (IV) analysis provides an alternative set of identification assumptions in the presence of uncontrolled confounding when attempting to estimate causal effects. Our objective was to evaluate the suitability of measures of prescriber preference and calendar time as potential IVs to evaluate the comparative effectiveness of buprenorphine/naloxone versus methadone for treatment of opioid use disorder (OUD). METHODS: Using linked population-level health administrative data, we constructed five IVs: prescribing preference at the individual, facility, and region levels (continuous and categorical variables), calendar time, and a binary prescriber's preference IV in analyzing the treatment assignment-treatment discontinuation association using both incident-user and prevalent-new-user designs. Using published guidelines, we assessed and compared each IV according to the four assumptions for IVs, employing both empirical assessment and content expertise. We evaluated the robustness of results using sensitivity analyses. RESULTS: The study sample included 35,904 incident users (43.3% on buprenorphine/naloxone) initiated on opioid agonist treatment by 1585 prescribers during the study period. While all candidate IVs were strong (A1) according to conventional criteria, by expert opinion, we found no evidence against assumptions of exclusion (A2), independence (A3), monotonicity (A4a), and homogeneity (A4b) for prescribing preference-based IV. Some criteria were violated for the calendar time-based IV. We determined that preference in provider-level prescribing, measured on a continuous scale, was the most suitable IV for comparative effectiveness of buprenorphine/naloxone and methadone for the treatment of OUD. CONCLUSIONS: Our results suggest that prescriber's preference measures are suitable IVs in comparative effectiveness studies of treatment for OUD.

Perceptions of provider awareness of traditional and cultural treatments among Indigenous people who use unregulated drugs in Vancouver, Canada.

INTRODUCTION: Indigenous people who use unregulated drugs (IPWUD) face significant barriers to care, including sparse availability of culturally safe health services. Integrating Indigenous traditional and cultural treatments (TCT) into health service delivery is one way to enhance culturally safe care. In a Canadian setting that implemented cultural safety reforms, we sought to examine the prevalence and correlates of client perceptions of primary care provider awareness of TCT among IPWUD. METHODS: Data were derived from two prospective cohort studies of PWUD in Vancouver, Canada between December 2017 and March 2020. A generalized linear mixed model with logit-link function was used to identify longitudinal factors associated with perceived provider awareness of TCT. RESULTS: Among a sample of 507 IPWUD who provided 1200 survey responses, a majority (n = 285, 56%) reported their primary care provider was aware of TCT. In multiple regression analyses, involvement in treatment decisions always (Adjusted Odds Ratio [AOR] = 3.6; 95% confidence interval [CI]: 1.6-7.8), involvement in treatment decisions most or some of the time (AOR = 3.3; 95% CI: 1.4-7.7), comfort with provider or clinic (AOR = 2.7; 95% CI: 1.5-5.0), and receiving care from a social support worker (AOR = 1.5; 95% CI: 1.0-2.1) were positively associated with provider awareness of TCT. CONCLUSION: We found high levels of perceived provider awareness of TCT and other domains of culturally safe care within a cohort of urban IPWUD. However, targeted initiatives that advance culturally safe care are required to improve healthcare and health outcomes for IPWUD, who continue to bear a disproportionate burden of substance use harms.

The Testing Imperative: Why the US Ending the Human Immunodeficiency Virus (HIV) Epidemic Program Needs to Renew Efforts to Expand HIV Testing in Clinical and Community-Based Settings.

Data from several modeling studies demonstrate that large-scale increases in human immunodeficiency virus (HIV) testing across settings with a high burden of HIV may produce the largest incidence reductions to support the US Ending the HIV Epidemic (EHE) initiative's goal of reducing new HIV infections 90% by 2030. Despite US Centers for Disease Control and Prevention's recommendations for routine HIV screening within clinical settings and at least yearly screening for individuals most at risk of acquiring HIV, fewer than half of US adults report ever receiving an HIV test. Furthermore, total domestic funding for HIV prevention has remained unchanged between 2013 and 2019. The authors describe the evidence supporting the value of expanded HIV testing, identify challenges in implementation, and present recommendations to address these barriers through approaches at local and federal levels to reach EHE targets.

Risk of severe infections after the introduction of biologic DMARDs in people with newly diagnosed rheumatoid arthritis: a population-based interrupted time-series analysis.

OBJECTIVES: To determine the impact of the introduction of biologic DMARDs (bDMARDs) on severe infections among people newly diagnosed with RA compared with non-RA individuals. METHODS: In this population-based retrospective cohort study using administrative data (from 1990-2015) for British Columbia, Canada, all incident RA patients diagnosed between 1995 and 2007 were identified. General population controls with no inflammatory arthritis were matched to RA patients based on age and gender, and were assigned the diagnosis date (i.e. index date) of the RA patients they were matched with. RA/controls were then divided into quarterly cohorts according to their index dates. The outcome of interest was all severe infections necessitating hospitalization or occurring during hospitalization after the index date. We calculated 8-year severe infection rates for each cohort and conducted interrupted time-series analyses to compare severe infection trends in RA/controls with index date during pre-bDMARDs (1995-2001) and post-bDMARDs (2003-2007) periods. RESULTS: A total of 60 226 and 588 499 incident RA/controls were identified. We identified 14 245 severe infections in RA, and 79 819 severe infections in controls. The 8-year severe infection rates decreased among RA/controls with increasing calendar year of index date in the pre-bDMARDs period, but increased over time only among RA, not controls, with index date in the post-bDMARDs period. The adjusted difference between the pre- and post-bDMARDs secular trends in 8-year severe infection rates was 1.85 (P = 0.001) in RA and 0.12 (P = 0.29) in non-RA. CONCLUSION: RA onset after bDMARDs introduction was associated with an elevated severe infection risk in RA patients compared with matched non-RA individuals.

Sensitivity to change of generic preference-based instruments (EQ-5D-3L, EQ-5D-5L, and HUI3) in the context of treatment for people with prescription-type opioid use disorder in Canada.

PURPOSE: Using data from a randomized controlled trial for treatment of prescription-type opioid use disorder in Canada, this study examines sensitivity to change in three preference-based instruments [EQ-5D-3L, EQ-5D-5L, and the Health Utilities Index Mark 3 (HUI3)] and explores an oft-overlooked consideration when working with contemporaneous responses for similar questions-data quality. METHODS: Analyses focused on the relative abilities of three instruments to capture change in health status. Distributional methods were used to categorize individuals as 'improved' or 'not improved' for eight anchors (seven clinical, one generic). Sensitivity to change was assessed using area under the ROC (receiver operating characteristics) curve (AUC) analysis and comparisons of mean change scores for three time periods. A 'strict' data quality criteria, defined a priori, was applied. Analyses were replicated using 'soft' and 'no' criteria. RESULTS: Data from 160 individuals were used in the analysis; 30% had at least one data quality violation at baseline. Despite mean index scores being significantly lower for the HUI3 compared with EQ-5D instruments at each time point, the magnitudes of change scores were similar. No instrument demonstrated superior sensitivity to change. While six of the 10 highest AUC estimates were for the HUI3, 'moderate' classifications of discriminative ability were identified in 12 (of 22) analyses for each EQ-5D instrument, compared with eight for the HUI3. CONCLUSION: Negligible differences were observed between the EQ-5D-3L, EQ-5D-5L, and HUI3 regarding the ability to measure change. The prevalence of data quality violations-which differed by ethnicity-requires further investigation.

Doing community-based research during dual public health emergencies (COVID and overdose).

Meaningful engagement and partnerships with people who use drugs are essential to conducting research that is relevant and impactful in supporting desired outcomes of drug consumption as well as reducing drug-related harms of overdose and COVID-19. Community-based participatory research is a key strategy for engaging communities in research that directly affects their lives. While there are growing descriptions of community-based participatory research with people who use drugs and identification of key principles for conducting research, there is a gap in relation to models and frameworks to guide research partnerships with people who use drugs. The purpose of this paper is to provide a framework for research partnerships between people who use drugs and academic researchers, collaboratively developed and implemented as part of an evaluation of a provincial prescribed safer supply initiative introduced during dual public health emergencies (overdose and COVID-19) in British Columbia, Canada. The framework shifts from having researchers choose among multiple models (advisory, partnership and employment) to incorporating multiple roles within an overall community-based participatory research approach. Advocacy by and for drug users was identified as a key role and reason for engaging in research. Overall, both academic researchers and Peer Research Associates benefited within this collaborative partnerships approach. Each offered their expertise, creating opportunities for omni-directional learning and enhancing the research. The shift from fixed models to flexible roles allows for a range of involvement that accommodates varying time, energy and resources. Facilitators of involvement include development of trust and partnering with networks of people who use drugs, equitable pay, a graduate-level research assistant dedicated to ongoing orientation and communication, technical supports as well as fluidity in roles and opportunities. Key challenges included working in geographically dispersed locations, maintaining contact and connection over the course of the project and ensuring ongoing sustainable but flexible employment.

Translating and disseminating a localised economic model to support implementation of the 'Ending the HIV Epidemic' initiative to public health policymakers.

Background: Despite significant progress in HIV treatment and prevention, the US remains far from its goal of 'Ending the HIV Epidemic' by 2030. Economic models using local data can synthesise the evidence to help policymakers allocate HIV resources efficiently, but persistent research-to-practice gaps remain. Little is known about how to facilitate the use of economic modelling data among local public health policymakers in real-world settings. Aims and objectives: To explore the dissemination of results from a locally-calibrated economic model for HIV prevention and treatment and identify the factors influencing potential uptake of the model for public health decision making at the local level. Methods: Four virtual focus groups with 26 local health department policymakers in Baltimore, Miami, Seattle, and New York City were held between July 2020 and May 2021. Qualitative content analysis of transcripts identified key themes around using the localised economic model in policy decisions. Results: Participants were interested in using local data in their decisions to allocate resources for HIV prevention/treatment. Six themes emerged: 1) importance of understanding local policy context; 2) health equity considerations; 3) using evidence to support current priorities; 4) difficulty of changing strategies, even incrementally; 5) bang for the incremental buck (efficiency) vs. previous impact; and 6) community values. Conclusion and relevance: To optimise acceptance and use of results from economic models, researchers should engage with local community members and public health decision makers early to understand budgetary and community priorities. Participants prioritised evidence that supports their existing strategies, considers budgets and funding streams, and improves health equity; however, real-world budget constraints and conflicting interests serve as barriers to implementing model recommendations and reaching national goals.

Opioid use disorder Cascade of care framework design: A roadmap.

Unintentional overdose deaths, most involving opioids, have eclipsed all other causes of US deaths for individuals less than 50 years of age. An estimated 2.4 to 5 million individuals have opioid use disorder (OUD) yet a minority receive treatment in a given year. Medications for OUD (MOUD) are the gold standard treatment for OUD however early dropout remains a major challenge for improving clinical outcomes. A Cascade of Care (CoC) framework, first popularized as a public health accountability strategy to stem the spread of HIV, has been adapted specifically for OUD. The CoC framework has been promoted by the NIH and several states and jurisdictions for organizing quality improvement efforts through clinical, policy, and administrative levers to improve OUD treatment initiation and retention. This roadmap details CoC design domains based on available data and potential linkages as individual state agencies and health systems typically rely on limited datasets subject to diverse legal and regulatory requirements constraining options for evaluations. Both graphical decision trees and catalogued studies are provided to help guide efforts by state agencies and health systems to improve data collection and monitoring efforts under the OUD CoC framework.

The Potential Epidemiological Impact of Coronavirus Disease 2019 (COVID-19) on the Human Immunodeficiency Virus (HIV) Epidemic and the Cost-effectiveness of Linked, Opt-out HIV Testing: A Modeling Study in 6 US Cities.

BACKGROUND: Widespread viral and serological testing for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may present a unique opportunity to also test for human immunodeficiency virus (HIV) infection. We estimated the potential impact of adding linked, opt-out HIV testing alongside SARS-CoV-2 testing on the HIV incidence and the cost-effectiveness of this strategy in 6 US cities. METHODS: Using a previously calibrated dynamic HIV transmission model, we constructed 3 sets of scenarios for each city: (1) sustained current levels of HIV-related treatment and prevention services (status quo); (2) temporary disruptions in health services and changes in sexual and injection risk behaviors at discrete levels between 0%-50%; and (3) linked HIV and SARS-CoV-2 testing offered to 10%-90% of the adult population in addition to Scenario 2. We estimated the cumulative number of HIV infections between 2020-2025 and the incremental cost-effectiveness ratios of linked HIV testing over 20 years. RESULTS: In the absence of linked, opt-out HIV testing, we estimated a total of a 16.5% decrease in HIV infections between 2020-2025 in the best-case scenario (50% reduction in risk behaviors and no service disruptions), and a 9.0% increase in the worst-case scenario (no behavioral change and 50% reduction in service access). We estimated that HIV testing (offered at 10%-90% levels) could avert a total of 576-7225 (1.6%-17.2%) new infections. The intervention would require an initial investment of $20.6M-$220.7M across cities; however, the intervention would ultimately result in savings in health-care costs in each city. CONCLUSIONS: A campaign in which HIV testing is linked with SARS-CoV-2 testing could substantially reduce the HIV incidence and reduce direct and indirect health care costs attributable to HIV.

Diagnosis of Opioid Use Disorder by Youths Assessed in Acute Care Settings in British Columbia, Canada.

OBJECTIVES: To describe trends in the number of youths diagnosed with opioid use disorder (OUD) and to identify factors associated with OUD diagnosis in acute care settings. STUDY DESIGN: Data from a population-based retrospective cohort study with linkage of 6 health administrative databases for 13 009 youth age 12-24 years identified with OUD between 2001 and 2018 in British Columbia, Canada were used to describe annual diagnoses. Using a multiple logistic regression model, we estimated the association between past-year health care utilization and OUD diagnosis in acute settings, controlling for sociodemographic and OUD-related comorbid conditions. RESULTS: Annual OUD diagnoses quadrupled between 2003 and 2017 (from 326 to 1473). Among the 6579 youth diagnosed with OUD between April 1, 2013 and September 30, 2018, 88.1% had past-year health system contacts. Youth age 12-18 had higher odds of OUD diagnosis in acute care (aOR 2.04; 95% CI 1.78, 2.34). Compared with no health care contact, youth receiving outpatient care only were less likely to be diagnosed with OUD in acute care (aOR 0.69; 95% CI 0.56, 0.84) and those with >1 urgent hospitalization were more likely to be diagnosed with OUD in acute care (aOR 1.87; 95% CI 1.40,2.49). CONCLUSIONS: More than 88% of youth had past-year health system contacts prior to diagnosis. Those age 12-18 years and with urgent hospitalizations in the year prior to diagnosis were more likely to have OUD diagnosed in acute care settings. Establishing an effective evidence-based system for early detection and intervention among youth with OUD must be a priority.

Cost-Effectiveness Analysis in Implementation Science: a Research Agenda and Call for Wider Application.

PURPOSE OF REVIEW: Cost-effectiveness analysis (CEA) can help identify the trade-offs decision makers face when confronted with alternative courses of action for the implementation of public health strategies. Application of CEA alongside implementation scientific studies remains limited. We aimed to identify areas for future development in order to enhance the uptake and impact of model-based CEA in implementation scientific research. RECENT FINDINGS: Important questions remain about how to broadly implement evidence-based public health interventions in routine practice. Establishing population-level implementation strategy components and distinct implementation phases, including planning for implementation, the time required to scale-up programs, and sustainment efforts required to maintain them, can help determine the data needed to quantify each of these elements. Model-based CEA can use these data to determine the added value associated with each of these elements across systems, settings, population subgroups, and levels of implementation to provide tailored guidance for evidence-based public health action. There is a need to integrate implementation science explicitly into CEA to adequately capture diverse real-world delivery contexts and make detailed, informed recommendations on the aspects of the implementation process that provide good value. We describe examples of how model-based CEA can integrate implementation scientific concepts and evidence to help tailor evaluations to local context. We also propose six distinct domains for methodological advancement in order to enhance the uptake and impact of model-based cost-effectiveness analysis in implementation scientific research.

The effect of British Columbia's Pharmacare coverage expansion for opioid agonist treatment.

Opioid agonist treatment (OAT) is the evidence-based standard of care for people with opioid use disorder. In British Columbia, Canada, only social assistance registrants received full coverage for OAT prior to the introduction of the Pharmacare Plan G coverage expansion on February 1st, 2017. We aimed to determine the effect of the coverage expansion on OAT initiation, re-initiation, and retention. Using linked population-level data, we executed a difference-in-differences analysis to compare outcomes of individuals eligible for the additional coverage and social assistance registrants already receiving the most generous coverage for OAT prior to the policy change, adjusting for individual and prescriber characteristics. We found Plan G coverage expansion significantly increased OAT retention. Specifically, coverage expansion decreased the number of OAT episode discontinuations by 12.8% (95% CI: 8.4%, 17.2%).

High prevalence of unmet healthcare need among people who use illicit drugs in a Canadian setting with publicly-funded interdisciplinary primary care clinics.

Background: People who use illicit drugs (PWUD) experience significant barriers to healthcare. However, little is known about levels of attachment to primary care (defined as having a regular family doctor or clinic they feel comfortable with) and its association with unmet healthcare needs in this population. In a Canadian setting that features novel publicly-funded interdisciplinary primary care clinics, we sought to examine the prevalence and correlates (including attachment to primary care) of unmet healthcare needs among PWUD. Methods: Data were derived from two prospective cohort studies of PWUD in Vancouver, Canada between December 2017 and November 2018. Multivariable logistic regression was used to identify factors associated with self-reported unmet healthcare needs among participants reporting any health issues. Results: In total, 743 (83.6%) of 889 eligible participants reported attachment to primary care and 220 (24.7%) reported an unmet healthcare need. In multivariable analyses, attachment to primary care at an integrated care clinic (adjusted odds ratio [AOR] = 0.14; 95% Confidence Interval [CI]: 0.06-0.34) was negatively associated with an unmet healthcare need, while being treated poorly at a healthcare facility (AOR = 5.50; 95% CI: 3.59-8.60) and self-reported chronic pain (AOR = 2.00, 95% CI: 1.30-3.01) were positively associated with an unmet healthcare need. Conclusion: Despite the high level of attachment to primary care, a quarter of our sample reported an unmet healthcare need. Our findings suggest that multi-level interventions are required to address the unmet need, including pain management and integrated care, to support PWUD with complex health needs.

Ending the HIV Epidemic Among Persons Who Inject Drugs: A Cost-Effectiveness Analysis in Six US Cities.

BACKGROUND: Persons who inject drugs (PWID) are at a disproportionately high risk of HIV infection. We aimed to determine the highest-valued combination implementation strategies to reduce the burden of HIV among PWID in 6 US cities. METHODS: Using a dynamic HIV transmission model calibrated for Atlanta, Baltimore, Los Angeles, Miami, New York City, and Seattle, we assessed the value of implementing combinations of evidence-based interventions at optimistic (drawn from best available evidence) or ideal (90% coverage) scale-up. We estimated reduction in HIV incidence among PWID, quality-adjusted life-years (QALYs), and incremental cost-effectiveness ratios (ICERs) for each city (10-year implementation; 20-year horizon; 2018 $ US). RESULTS: Combinations that maximized health benefits contained between 6 (Atlanta and Seattle) and 12 (Miami) interventions with ICER values ranging from $94 069/QALY in Los Angeles to $146 256/QALY in Miami. These strategies reduced HIV incidence by 8.1% (credible interval [CI], 2.8%-13.2%) in Seattle and 54.4% (CI, 37.6%-73.9%) in Miami. Incidence reduction reached 16.1%-75.5% at ideal scale. CONCLUSIONS: Evidence-based interventions targeted to PWID can deliver considerable value; however, ending the HIV epidemic among PWID will require innovative implementation strategies and supporting programs to reduce social and structural barriers to care.

Contact Tracing for COVID-19: An Opportunity to Reduce Health Disparities and End the Human Immunodeficiency Virus/AIDS Epidemic in the United States.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) testing and contact tracing have been proposed as critical components of a safe and effective coronavirus disease 2019 (COVID-19) public health strategy. We argue that COVID-19 contact tracing may provide a unique opportunity to also conduct widespread HIV testing, among other health-promotion activities.

"Ending the Epidemic" Will Not Happen Without Addressing Racial/Ethnic Disparities in the United States Human Immunodeficiency Virus Epidemic.

We estimated human immunodeficiency virus incidence and incidence rate ratios (IRRs) for black and Hispanic vs white populations in 6 cities in the United States (2020-2030). Large reductions in incidence are possible, but without elimination of disparities in healthcare access, we found that wide disparities persisted for black compared with white populations in particular (lowest IRR, 1.69 [95% credible interval, 1.19-2.30]).

Prioritizing Additional Data Collection to Reduce Decision Uncertainty in the HIV/AIDS Response in 6 US Cities: A Value of Information Analysis.

OBJECTIVES: The ambitious goals of the US Ending the HIV Epidemic initiative will require a targeted, context-specific public health response. Model-based economic evaluation provides useful guidance for decision making while characterizing decision uncertainty. We aim to quantify the value of eliminating uncertainty about different parameters in selecting combination implementation strategies to reduce the public health burden of HIV/AIDS in 6 US cities and identify future data collection priorities. METHODS: We used a dynamic compartmental HIV transmission model developed for 6 US cities to evaluate the cost-effectiveness of a range of combination implementation strategies. Using a metamodeling approach with nonparametric and deep learning methods, we calculated the expected value of perfect information, representing the maximum value of further research to eliminate decision uncertainty, and the expected value of partial perfect information for key groups of parameters that would be collected together in practice. RESULTS: The population expected value of perfect information ranged from $59 683 (Miami) to $54 108 679 (Los Angeles). The rank ordering of expected value of partial perfect information on key groups of parameters were largely consistent across cities and highest for parameters pertaining to HIV risk behaviors, probability of HIV transmission, health service engagement, HIV-related mortality, health utility weights, and healthcare costs. Los Angeles was an exception, where parameters on retention in pre-exposure prophylaxis ranked highest in contributing to decision uncertainty. CONCLUSIONS: Funding additional data collection on HIV/AIDS may be warranted in Baltimore, Los Angeles, and New York City. Value of information analysis should be embedded into decision-making processes on funding future research and public health intervention.

Ending the Epidemic in America Will Not Happen if the Status Quo Continues: Modeled Projections for Human Immunodeficiency Virus Incidence in 6 US Cities.

We estimated 10-year (2020-2030) trajectories for human immunodeficiency virus incidence in 6 US cities. Estimated incidence will only decrease in 2 of 6 cities, with the overall population-weighted incidence decreasing 3.1% (95% credible interval [CrI], -1.0% to 8.5%) by 2025, and 4.3% (95% CrI, -2.6% to 12.7%) by 2030 across cities. Targeted, context-specific combination implementation strategies will be necessary to meet the newly established national targets.

Geographic variation in the costs of medical care for people living with HIV in British Columbia, Canada.

BACKGROUND: Regional variation in medical care costs can indicate heterogeneity in clinical practice, inequities in access, or inefficiencies in service delivery. We aimed to estimate regional variation in medical costs for people living with HIV (PLHIV), adjusting for demographics and case-mix. METHODS: We conducted a retrospective cohort study using linked health administrative databases of PLHIV, from 2010 to 2014, in British Columbia (BC), Canada. Quarterly health care costs (2018 CAD) were derived from inpatient, outpatient, prescription drugs, antiretroviral therapy (ART), and HIV diagnostics. We used a two-part model with a logit link for the probability of incurring costs, and a log link and gamma distribution for observations with positive costs. We also estimated quarterly utilization rates for hospitalization-, physician billing- and prescription drug-days. Primary variables were indicators of individuals' Health Service Delivery Area (HSDA). We adjusted cost and utilization estimates for demographic characteristics, HIV-disease progression, and comorbidities. RESULTS: Our cohort included 9577 PLHIV (median age 45.5 years, 80% male). Adjusted total quarterly costs for all 16 HSDAs were within 20% of the provincial mean, 8/16 for hospitalization costs, 16/16 for physician billing costs and 10/16 for prescription drug costs. Northern Interior and Northeast HSDAs had 38 and 44% lower quarterly non-ART prescription drug costs, and 2 and 5% higher quarterly inpatient costs, respectively. CONCLUSIONS: We observed limited variation in medical care costs and utilization among PLHIV in BC. However, lower levels of outpatient care and higher levels of inpatient care indicate possible barriers to accessing care among PLHIV in the most rural regions of the province.

Cost-Effectiveness of Publicly Funded Treatment of Opioid Use Disorder in California.

Background: Only 1 in 5 of the nearly 2.4 million Americans with an opioid use disorder received treatment in 2015. Fewer than half of Californians who received treatment in 2014 received opioid agonist treatment (OAT), and regulations for admission to OAT in California are more stringent than federal regulations. Objective: To determine the cost-effectiveness of OAT for all treatment recipients compared with the observed standard of care for patients presenting with opioid use disorder to California's publicly funded treatment facilities. Design: Model-based cost-effectiveness analysis. Data Sources: Linked population-level administrative databases capturing treatment and criminal justice records for California (2006 to 2010); published literature. Target Population: Persons initially presenting for publicly funded treatment of opioid use disorder. Time Horizon: Lifetime. Perspective: Societal. Intervention: Immediate access to OAT with methadone for all treatment recipients compared with the observed standard of care (54.3% initiate opioid use disorder treatment with medically managed withdrawal). Outcome Measures: Discounted quality-adjusted life-years (QALYs) and discounted costs. Results of Base-Case Analysis: Immediate access to OAT for all treatment recipients costs less (by $78 257), with patients accumulating more QALYs (by 0.42) than with the observed standard of care. In a hypothetical scenario where all Californians starting treatment of opioid use disorder in 2014 had immediate access to OAT, total lifetime savings for this cohort could be as high as $3.8 billion. Results of Sensitivity Analysis: 99.6% of the 2000 simulations resulted in lower costs and more QALYs. Limitation: Nonrandomized delivery of OAT or medically managed withdrawal. Conclusion: The value of publicly funded treatment of opioid use disorder in California is maximized when OAT is delivered to all patients presenting for treatment, providing greater health benefits and cost savings than the observed standard of care. Primary Funding Source: National Institute on Drug Abuse.