Background and approach   Opioid agonist therapy (OAT) is evidence based, effective treatment of heroin and other forms of opioid dependence. It involves prescribing opioid medications such as methadone and buprenorphine (buprenorphine or a combination of buprenorphine and naloxone) at a maintenance dose. Both medications are included in the WHO Model List of Essential Medicines for the treatment of opioid dependence. WHO clinical guidance recommends this approach for the treatment of opioid dependence and for a comprehensive public health response to HIV, tuberculosis (TB) and hepatitis C (HCV) among people who inject drugs (PWID). The Global Fund considers OAT as a part of the package of the key harm reduction interventions and widely supports its implementation.   Domestic public, and in some cases private, sources now fully fund opioid OAT programs in Central Europe, most of South-Eastern Europe and the Baltic States. At the same time in Eastern Europe and Central Asia (EECA) several countries, notably Azerbaijan, Belarus, Georgia, Kazakhstan, Moldova and Ukraine, have begun financing, or co-financing, OAT services from domestic funds, while others continue to depend on donor support, largely from the Global Fund.   As the Global Fund is transitioning from the majority of EECA countries, there is a concern regarding the sustainability of OAT once donor support and international technical assistance cease to be provided. According to Harm Reduction International, in 2022 only 6% of the estimated funding required for OAT and other harm reduction interventions was available in low- and middle-income countries, coming in equal portions from domestic public resources and donors.   To address these concerns, the Eurasian Harm Reduction Association, with support from an International Advisory Group, developed a methodology to assess progress and risks to programmatic and financial sustainability of OAT programs in countries transitioning from the Global Fund and other international donor support. The methodology was piloted in 2019–2020 in three EECA countries: Belarus, Ukraine and Tajikistan. Following the pilot the updated methodology was used for re-assessment of OAT sustainability in the three pilot countries as well as in Moldova and has been applied once in Albania and Kyrgyzstan. All assessment reports are available for download here.   The OAT sustainability assessment tool is designed to be utilized by civil society and researchers in any country with an operational OAT program, to shed light on areas of strength or weakness on financial or programmatic sustainability and inform advocacy, policy and decision-making. The OAT sustainability tool breaks down the concept of sustainability into a matrix of key indicators, grouped into the following three broad dimensions required for continuation and scale-up of OAT: Policy & Governance; Finance & Resources, and Services. For each of these three dimensions, a set of indicators is proposed (see Table 1), and several benchmarks are offered on how to measure progress under each indicator that utilizes existing international guidance on OAT. The methodology is described in detail in a 2024 article in the Harm Reduction Journal.   Findings from the assessments of OAT program sustainability in 2020 and 2022/2023 in the context of transition from Global Fund support to public funding in four EECA countries (Belarus, Republic of Moldova, Tajikistan and Ukraine) were also published in Harm Reduction Journal in late 2024. Collectively, these eight assessments involved 83 key informant interviews 13 focus groups with OAT clients.   OAT sustainability during Global Fund transition in four EECA countries   The study provides the detailed overview of progress towards ensuring OAT sustainability in four countries across three dimensions, each with nine specific indicators (see Table 1). Crucially, no country reported a high degree of OAT sustainability across the three dimensions. At a more granular level, a high degree of sustainability was reported for at least one indicator in three countries: Medicines (Belarus, Moldova); Financial resources (Belarus, Moldova); Evidence and information systems (Ukraine); Service Accessibility (Belarus); and Service integration & quality (Ukraine).   According to the study results, between 2020 and 2022/2023 all four countries made improvements to increase OAT sustainability. In 2022, Ukraine had a substantial degree of sustainability, followed by Belarus and Moldova with a moderate degree, while Tajikistan’s sustainability was at moderate-to-high risk.         Sustainability scores between 2020-2022 remained at similar levels in Moldova and Tajikistan, while in Belarus, and particularly in Ukraine, sustainability improved. In 2020, Moldova received the highest OAT sustainability scores, followed by Belarus and Ukraine. Tajikistan was assessed as having OAT at moderate-to-high risk across all dimensions in both years. For Ukraine, the degree of sustainability on the ‘Finance & Resources’ dimension was on an improving trajectory in 2020 before the escalation of the war conflict in 2022. State resources were reallocated and the Global Fund stepped in to provide support. Therefore, no improvements in this dimension were registered between 2020 and the end of 2022. Overall, however, Ukraine achieved the greatest progress among the four countries analysed since 2020.   Overall, the highest improvements between 2020 and 2022 were recorded for the indicators on Availability & coverage, Financial resources, Service quality & integration and Service accessibility. These improvements reflect the impact of advocacy efforts from experts, clients, donors and technical partners to improve services and financial transition. Two supportive factors were inclusion of OAT in the financing of UHC schemes and donor requirements for co-financing. Additionally, significant efforts by health professionals and organised networks of OAT clients prioritised service improvements, which is demonstrated by the increased number of community-led research and inclusion of client perspectives in local surveys.   The greatest risks to OAT sustainability across all countries, but in particular for Belarus and Tajikistan, related to the Service Availability and coverage indicator (following the link you may find the detailed comparison across four countries of the selected OAT markers related to availability, coverage, quality and integration of OAT service). Those risks were exacerbated by low service coverage - below 10% - in the four countries, as well as the limited availability of OAT outside public sector specialised narcology facilities and, in some countries, the ongoing low use of take-home doses. The study also raised a concern that the least progress, or even a decline, in the Human resources indicator was affecting OAT sustainability.   Discussion and conclusions   While the four countries rolled out their OAT programs at similar times, the pace of development and their approaches varied. OAT is increasingly recognized as part of core health care services, with state funding invested in all four middle-income countries analyzed; however, there is limited will to scale-up and fully address need. All four countries have clinical guidelines and leadership on OAT from the drug treatment system. Nevertheless, political support and the accountability mechanisms for scale-up and domestic investments continue to draw mainly from national HIV strategies, programs and budgets.   Transition planning and management of the national HIV programs have had a positive role in increasing the sustainability of OAT by presenting a vision and plan for sustaining various elements, particularly financial resources. Still, programmatic and other aspects of sustainability are overlooked in donor transition planning. Some chronic challenges related to restrictive circulation of OAT medicines, limited client rights, and negative attitudes towards treatment from some health professionals remain in place some 20 years since the start of OAT in the four countries.   Ukraine has had the most significant shifts across several indicators because the country expanded service provision outside the specialized settings, with a lower threshold for service delivery and access. Its retention of clients was among the highest among the four countries. Additionally, Ukraine was the only country reporting waiting lists of people keen to join treatment and had the highest coverage of the four states. This could be interpreted as improved integration of OAT in the broader health system and the lowering of service thresholds, positively affecting treatment demand. After the start of full-scale war in Ukraine in 2022, some experts anticipated a reduction in political support for OAT among Russian allies, such as Belarus. However, the assessment did not observe such change. But it is clear that territories in active war or frozen conflicts, like those in Ukraine and Moldova, require a different timeline for donor exit and collective solutions and, in the case of OAT, might not be possible without broader geopolitical changes.   The study also highlights the human resource shortages, ageing and anti-OAT views among drug treatment specialists. There is a growing recognition of the need to address the general human resource crises in the health sector across Europe. However, so far, this system-building block has been understated in sustainability and transition planning and should receive greater prioritization in the future, including for OAT sustainability building. One solution could be to follow Ukraine’s example and expand its delivery outside of specialized state health settings.   To conclude - after 20 years, OAT sustainability in the four countries still remains at risk and requires further planning and management. Technical partners and donors should continue supporting this work through the dual lenses of HIV and drug policy. OAT program resilience, and ability to scale up, depends on multiple factors, including political will and domestic public funding. Ukraine exemplifies the ability to address both previously documented challenges, such as rigid stock management and high specialization of service providers, as well as new obstacles related to the country being at war and enduring a difficult economic period, demonstrating that building sustainability is not only about securing domestic funding.   There needs to be an increased focus on programmatic elements of OAT sustainability — the resource inputs and service attractiveness (including the quality of their provision) across the four countries. The study offers a review of those needs and suggests pathways going forward. Some of the follow-up steps could benefit from cooperation and synergies with teams working on sustainability in the HIV and TB fields (such as medication procurement, UHC packages, multidisciplinary care and integration in primary settings). Transformation of drug treatment systems, including their funding methods, could facilitate more responsive and competitive provision of services. Broader reforms of national drug policies to reduce barriers to controlled medicines could have multifaceted effects on all three dimensions of sustainability and, therefore, should remain a priority for the future.   The developed methodology enables a comprehensive review of the resilience of OAT programs and their ability to scale up and to inform the development of paths forward. While developed and applied in the EECA context, the methodology has potential for application in other countries including those from other regions where transition from donor’s support is also taking place and may threaten the sustainability of OAT programs. The instrument produces outputs highlighting specific elements that could inform a roadmap for improved sustainability of OAT programs.