The use of illicit drugs has become a major public health issue worldwide, with approximately 275 million people reporting past-year use of any illicit drugs in the World Drug Report 2021 [1]. Specifically, the number of people who had past-year use of opioids reached more than 61 million, or 1.22% of the global population, in the 2022 report [2]. Since opioids account for two-thirds of drug-related deaths, mostly from overdoses, the control of their use and the coverage of related treatments have become challenging global issues [2].

Harm reduction programs are effective measures for decreasing the harm caused by the use of opioids, particularly by injection, mainly via medication-assisted treatment using methadone [3]. However, despite the widespread adoption of harm reduction programs among Western countries after the mid-twentieth century, similar programs were not initiated in Asian countries until the last decade of the century [4]. The slow adoption in Asia might result from concern about the spillover effect of harm reduction programs, such as conflict with past mainstream government approaches that viewed addiction as a “crime” rather than a “disease” [5], anxiety about the potential diversion of opioid agonist medications [6], and the debate about whether applying substitute drugs as treatment would send the wrong message to the public [7].

Not until 2006 did the Taiwanese government initiate its own harm reduction program to mitigate the rapid growth of the human immunodeficiency virus (HIV) epidemic among people with injection drug use [8]. The nationwide harm reduction program consisted of three-pronged policies, including the expansion of extant education and screening, a needle-syringe program (NSP), and opioid substitution therapy (OST) [9]. At the beginning of the OST, only methadone maintenance treatment (MMT) was provided until the option of buprenorphine maintenance treatment became available nationwide in 2010. Although Taiwan implemented national health insurance (NHI) in 1995 to provide general health services, the expenditure for treatment for drug dependence is explicitly excluded from this coverage by law. Thus, the government allocated a special budget to decrease patients’ copayment for the cost of MMT. The number of participants receiving MMT grew rapidly in the first 3 years to approximately 12,590 participants per month in 2008 [8], but it gradually dropped to 8,000 participants or less per month in 2017 [10]. Nevertheless, people with heroin use who attended MMT clinics were found to have a better quality of life than those who did not attend MMT clinics [11], and participants with a longer cumulative MMT duration were associated with lower all-cause and drug-related mortality rates [12].

To enhance the overall capacity of treatment for people with illicit drug use disorders, the government in 2017 adopted the “New-Generation Strategy to Combat Drug Abuse” (hereafter referred to as the new-generation strategy), in which governmental sectors across law enforcement, education, and health and welfare were incorporated in a united task force. With support from this strategy, the Ministry of Health and Welfare (MOHW) successively launched two funding programs to alleviate the decline in MMT participants: the Patients’ Medical Expenditure Supplements (PMES) program in January 2019 and the MMT Clinics Accessibility Maintenance (MCAM) program in September 2019. The issue now is how to evaluate the impact of these two programs in an appropriate policy implementation framework.

Policy implementation framework

Based on the two-part conceptual framework of implementation synthesized in a recent review [13], the implementation of these two funding programs on MMT clinics in Taiwan could be described in two parts: (1) the process model of implementation consisting of policy package and process, and (2) determinants framework consisting of policy instruments, strategies, and policy context.

Process model of implementation—policy package and process

The opening of MMT clinics in any medical institution requires the signing of contracts with the MOHW. Based on resourcefulness in service, the MMT clinics were categorized into three facility levels: core hospitals, hospitals, and clinics. All of the treatment plans, treatment procedures, space planning, and storage plans for controlled drugs in MMT clinics must be inspected regularly by the local government. The set-up of MMT clinics was first as a pilot in four major sites in 2005 and then expanded to every city and county in 2006 [8]. After a dramatic decline in the incidence of HIV infection among people with injection drug use in 2007 [14] owing to a fast implementation that was rated as a successful model in a systemic review [15], the MMT program continues to be an important component of the harm reduction for people with heroin use in Taiwan.

Patients attending the clinic will receive a full subsidy for the test fee for infectious diseases and for the methadone medication fee, as well as a partial subsidy for the remaining tests by the MOHW. If a patient is diagnosed with HIV infection, all the aforementioned costs from the MMT become fully subsidized. When legal amendments to allow deferred prosecution nationwide were enacted in 2008, the number of participants receiving MMT peaked in this year [8]. Facing the challenge of the gradual decline in the number of MMT participants afterward, the new-generation strategy provided the MOHW extra resources to successively launch the PMES and MCAM.

Determinants frameworkPolicy instruments and strategies

The legislative changes for setting up the “Drug Use Prevention Fund” for the new-generation strategy have served as the major financial system infrastructure in the implementation of MMT policy interventions. In 2017, the central government amended “Narcotics Hazard Prevention Act” to set up an independent fund to support programs related to drug abuse prevention and treatment in related governmental sectors. The sources of funding include regular government budget, fines due to the violation of the law, donations, and any other possible income related to drug use regulations. The total funding amount in 2019 was NT$361.10 million (US$11.67 million). Hence, the set-up of “Drug Use Prevention fund” has secured the maintenance of drug-related policy interventions.

Other strategies included building up a “National Case Management System of Drug and Alcohol Use” and connecting to the existing medical information system used by every MMT clinic. The applications for subsidy are conducted online to minimize the administrative burden of the staff in the MMT clinics. Additionally, advertisements and health education leaflets are sent to each MMT clinic to enhance the dissemination. Another strategy was to maintain constant communications between the central government and local governments to assist MMT clinics in participating in these policy interventions. Lastly, the MMT clinic's participation rate in the policy interventions was chosen as an indicator for the performance evaluation of each local health agency.

The close connections developed over decades between the MOHW and medical institutions nationwide might also be beneficial to the implementation process. In particular, the connections have been strengthened since the launch of NHI, which has covered approximately 99.99% of the citizens and contracted 92.04% of the medical facilities (e.g., hospitals, clinics, and pharmacies) [16].

Context of the MMT policy intervention

Starting in January 2019, the PMES program was launched to further subsidize necessary procedures for people with heroin use attending MMT clinics, including additional assessments, psychotherapy, and miscellaneous expenditures (see more details in Supplementary Table S1). Nevertheless, patients typically need to pay the remaining costs since the PMES sets a yearly cap for each patient. With an average median household income of $NT 905 thousand (US$ 29.26 thousand) in 2019 [17], the total funding amount of the PMES in the same year was approximately $NT 98.36 million (US$ 3.18 million). Almost 100% of the subsidization applications for the items in the PMES were approved. Among the total amount subsidized, the top 5 categories were fee for assessment at outpatient clinics (30.02%), urine drug tests (18.78%), case management (11.21%), individual psychotherapy (10.61%), and diagnostic interview (7.14%). In specific items, the fee related to psychotherapy, including individual and group psychotherapy, accounted for 15.49%.

As the number of patients per MMT clinic continued to dwindle during the implementation of the PMES program, the MCAM program was launched in September 2019 to help medical institutions with MMT clinics serving a monthly average number of daily participants of 150 or less by their capacity levels: tiny (1–50), small (51–100), and medium (101–150). For MMT clinics with larger capacities that were not eligible for the MCAM, we designated their scale as “large”, i.e., monthly average number of daily participants of 150 to 700. To compensate for the cost of MMT clinics with smaller capacities, the ceilings of yearly MCAM funding are set at $NT550 thousand (US$17.78 thousand) for tiny clinics, 350 thousand (US$11.31 thousand) for small clinics, and 200 thousand (US$6.47 thousand) for medium-scale clinics. The total funding amount for the MCAM in 2019 was $NT 45.10 million (US$ 1.46 million). Once funded, the MMT clinics are asked to expand their manpower by adding one part-time case manager for tiny clinics, one full-time case manager for small clinics, and two full-time case managers for medium-scale clinics.

Gaps and study aims

Although both the PMES and the MCAM have been implemented since 2019, the impact of these two funding programs on MMT clinics has not yet been rigorously evaluated. Traditional studies have applied randomization or used a control group, which tends to be impractical for public funding programs. A meaningful evaluation of policy interventions poses several methodological challenges, such as the definition of the groups to be compared, the separation of the effect from time to policy, the statistical approaches chosen for evaluation, and the solution to longitudinal correlation within study units [18]. Since the initiation time and the intervention targets of both the PMES and the MCAM are relatively clear, a single interrupted time series analysis (SITSA), which is suitable for a nonrandomized intervention [19], could be used to quantitatively measure the impact of the two policy interventions. In particular, two indices are important in quantifying the efficacy of the policy interventions on MMT clinics, i.e., the monthly average number of daily participants per clinic and the 3-month retention rate. Hence, using SITSA, this study aimed to (1) evaluate the impact of the PMES on the monthly average participants and the 3-month retention rate of MMT clinics from February 2013 to December 2019 and (2) evaluate the impact of the MCAM on the monthly average participants of MMT clinics from September 2019 to December 2019. All analyses were further stratified according to the capacity scale of the MMT clinics.