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The NIDA clinical trials network: evolving, expanding, and addressing the opioid epidemic


Over the past two decades, the National Drug Abuse Treatment Clinical Trials Network (CTN), a program of the National Institute on Drug Abuse (NIDA), has expanded from the initial six Nodes to 16 Nodes, as a nationwide consortium of research scientists and treatment providers working together to improve care for substance use in the nation’s communities. Encompassing both specialty care programs and general medical settings, the Network has become a unique resource for expertise on clinically focused research, bridging the gap between research and treatment delivery. Over 22 years, the CTN has completed 101 studies, resulting in 650 publications. In response to the opioid epidemic, a CTN task force generated a comprehensive list of research priorities in the areas of prevention, treatment, knowledge dissemination, and workforce training, to form the basis of the Network’s opioid portfolio. The Network’s opioid portfolio currently includes five main categories of studies: (1) large multi-site studies; (2) studies aimed at closing the treatment gap; (3) expansion of ongoing studies to improve service delivery and implementation; (4) studies to explore the use of substance use data in electronic health record systems; (5) training and dissemination projects to expand the research/health care provider workforce. With funding from the Helping to End Addiction Long-Term InitiativeSM (HEAL), the CTN established five new Nodes, which, along with the pre-existing Nodes, are distributed in every region of the nation and engage researchers and clinicians in areas that have been among the hardest hit by the opioid epidemic. Through this expanded network and its commitment to developing personalized, evidence-based treatments, the CTN is poised to address and provide solutions for the ongoing epidemic of opioid use and addiction.


The National Drug Abuse Treatment Clinical Trials Network (CTN), a program of the National Institute on Drug Abuse (NIDA), is a nationwide consortium of research scientists and treatment providers working together to improve care for substance use in the nation’s communities. NIDA established the CTN in 1999 following an Institute of Medicine (IOM) call for academic researchers to focus greater attention on treatment providers’ needs, and for providers to more readily adopt evidence-based practices [1]. Over the course of two decades, the Network has become a unique resource for expertise on clinically focused research with an extensive infrastructure that encompasses both specialty care programs and general medical settings. Today, it is ideally positioned to rapidly test and disseminate practical, readily applicable solutions to alleviate the nation’s deadly epidemic of opioid use and addiction.

At the interface of science and treatment provision

The CTN is a Network of Nodes, each comprising one or more academic centers linked to nearby health systems, treatment programs, and provider practices. The researchers and providers in the CTN Nodes collaborate to design and conduct rigorous, multi-site clinical trials and other clinical studies that have potential to improve substance use treatment access or outcomes. To date, the Network has initiated over 100 studies, and Network investigators have published over 650 papers. This work has opened pathways for significant new treatment approaches and shed important light on treatment alternatives. One recent trial, for example, was instrumental in convincing the U.S. Food and Drug Administration to grant clearance, for the first time for any disease, for a digital therapeutic [2]. The trial showed that the therapy, called reSET in its commercial digital therapeutic form, effectively treats cannabis, cocaine, stimulant, and alcohol use disorders [3].

To initiate a research project in the CTN, the researchers and providers in a Node or Nodes submit a research proposal to the CTN Research Development Committee for peer review. Review criteria are no less stringent than those used to assess the worthiness of any NIH research: (1) significance of the research question, (2) investigators’ experience, (3) innovation, (4) approach to the research question, (5) environment, (6) readiness for multi-site implementation, and (7) budget. Proposals with adequate scores and programmatic priority advance to research protocol development, with input and assistance from the Network data and statistics coordinating center and clinical coordinating center. Most projects in the CTN are led cooperatively by investigators from multiple Nodes; this practice, and the multi-site nature of the trials, ensure that as many collaborators as is practical feel ownership in, contribute to, and learn from the project.

Through their participation in the CTN, researchers have become better acquainted with treatment providers’ practical concerns, and providers have learned to formulate research questions and conduct clinical research with high scientific and ethical integrity. Young scientists also obtain training and mentoring from the CTN, either by joining a project or through a fellowship arrangement. The CTN’s training platform also extends internationally, via its INVEST fellowships.

For the first years of the Network’s existence, almost all participating treatment providers worked in specialized community substance use treatment programs. Today, partners include primary care, emergency care, and other non-substance use specialty providers. This crucial expansion enables the Network to take advantage of opportunities arising from health care reforms that have integrated substance use care, for the first time, with mainstream medicine [4]. The Mental Health Parity and Addiction Equity Act of 2008 and the Affordable Care Act (ACA) of 2010 mandate that insurers cover and reimburse treatment for substance use disorders similarly to other chronic diseases [5]. Federal and state laws now authorize practitioners with a broader array of credentials to provide substance use treatment, and in more diverse settings, compared to previously.

These reforms established essential conditions for the goal that has guided CTN research since its beginning: a comprehensive treatment system that answers to the chronic nature of substance use disorders [6]. Such a system will integrate substance use treatment with care for comorbid somatic and psychological conditions. In such a system, every encounter with a medical professional will include an assessment potentially leading to treatment or referral for treatment. However, although health care reforms have greatly enhanced prospects for reaching this goal, many challenges remain in the way of making it a reality. These include identifying appropriate roles for many types of practitioners in substance use treatment, assessing and addressing their educational needs with respect to substance use issues, and establishing mechanisms of coordination. The CTN, with its abundant experience in practice-oriented research and rich two-way relationships with providers in both specialty care and general medical settings, is well equipped to tackle these problems.

The Network and the opioid epidemic

In 2015, after rising steadily since 1999, the number of people in the U.S. dying annually from opioid overdoses began a sharp ascent [7]. By 2017, the yearly death toll was over 47,000 [8], more than the number of traffic fatalities [9], and an estimated 2.1 million people were estimated to have an opioid use disorder [10]. For the first time in decades, overall life expectancy in the United States fell, due in large part to deaths from drug overdoses [11].

Alarmed by this escalation, the CTN in 2016 formed a special opioid task force to determine how best to mobilize its resources to combat the epidemic. The task force generated a comprehensive list of research priorities in the areas of prevention, treatment, knowledge dissemination, and workforce training (Table 1). This list remains the basis of the Network’s opioid research portfolio today.

Table 1 CTN Opioid Research Goals

The Network’s strategy assigns the highest priority to research and education to optimize the use of medication for opioid use disorder (MOUD). In the United States, medications approved for the treatment of opioid use disorder (OUD) include buprenorphine, extended-release naltrexone, and methadone; buprenorphine and extended-release naltrexone can be prescribed and managed in office-based practice [12, 13]. If used to their fullest potential, these medications could significantly curtail the impact of the opioid epidemic. Instead, they are grossly underused [14,15,16], and when they are used, it is often to less than their full potential [17]. Multiple factors contribute to this situation, including regulations that require special licensing and limit caseloads, lack of proficiency in initiating and managing these treatments, and disjointed service delivery and coordination [18, 19]. Other barriers include limited geographic access to treatment providers [20], stigma associated with OUD, and a lack of resources for many patients who are in compromised economic conditions [21].

The CTN set objectives of increasing MOUD use in general medical settings and improving MOUD treatment quality and patient engagement, all within the context of a fully integrated continuum of care. A recent multi-site trial illustrates the CTN’s capacity to promote these goals by clarifying issues that can complicate and hinder effective treatment decisions. The results demonstrated that buprenorphine and extended-release naltrexone are equally effective for patients who complete initiation, but that more patients drop out of treatment before completing initiation on extended-release naltrexone [22]. This is highly useful information for providers and patients; it reinforces the need to assist patients through the difficult process of completely withdrawing from misused opioids that must precede initiation on naltrexone, an opioid antagonist. (Buprenorphine, an opioid partial agonist, requires only that patients enter withdrawal.)

In 2017, the president declared the opioid epidemic a national public health emergency [23]. As part of the government-wide response to the epidemic, Congress gave the National Institutes of Health (NIH) a supplemental appropriation to conduct the Helping to End Addiction Long-Term InitiativeSM (HEAL) ( The NIH and NIDA directed a substantial share of HEAL funding to an expansion of the CTN and its opioid research efforts, recognizing the Network’s mature capacity and readiness to rapidly test ideas for practice improvements, in trials ranging from small and local to nationwide, and to facilitate the introduction of research findings into actual practice.

With HEAL funding, the CTN established five new Nodes, which, along with the pre-existing Nodes, are distributed in every region of the nation (Fig. 1). The new Nodes have engaged researchers and clinicians in areas that have been among the hardest hit by the opioid epidemic: Appalachian (Western Pennsylvania and West Virginia), Greater Intermountain (Utah), Great Lakes (Illinois and Wisconsin), Southwest (New Mexico), and Greater Southern California. The Network expanded its already ambitious opioid portfolio to encompass five categories of studies (Table 2):

  • Large multi-site studies to answer questions that previously were out of reach due to budget constraints. Among these are: (a) how best to engage and equip personnel at more patient encounter points, (e.g., family medical practices, community pharmacies, obstetrics and gynecology practices) to identify and refer people with substance use issues for treatment, etc.; (b) how to efficiently coordinate substance use treatment with treatment for other patient conditions in primary care; and, (c) how to amplify the substance use treatment workforce.

  • Studies aimed at closing the treatment gap, by determining how best to deliver quality treatment to severely underserved populations.

  • Expansion of ongoing studies to efficiently generate essential knowledge on improving service delivery and implementation.

  • Studies to explore the inclusion of substance use data in electronic health record systems, and the potential for these data to generate relevant clinical information and enhance patient care.

  • Training and dissemination projects to expand the research/health care provider workforce.

Fig. 1
figure 1

Map of CTN Nodes

In recognition of the dissemination and implementation hurdles that often slow the translation of research findings into practice, many of these studies are designed to evaluate not only the clinical effectiveness of the treatment strategies of interest, but also the feasibility and efficacy of methods for implementing those strategies in the “real world.”

Table 2 CTN HEAL Projects


The NIDA CTN, like the IOM, views bridging research and treatment provision as a critical route to a treatment system that can provide every patient with a personalized, evidence-based continuum of care for their substance use disorders. The Network has nurtured and continues to expand a nationwide contingent of clinically aware researchers, clinician-researchers, and research-attuned providers. Throughout its history, the Network has adapted to take advantage of new opportunities, recent examples being research on digital therapeutics [24] and data science [25]. Its history and growth have endowed the CTN with capacity to play a unique role in addressing the ongoing epidemic of opioid use and overdose.

Availability of data and materials

Not applicable.



Clinical Trials Network


National Institute on Drug Abuse


Institute of Medicine


Affordable Care Act


Medication for Opioid Use Disorder


Opioid Use Disorder


National Institutes of Health


Helping to End Addiction Long-term


Neonatal opioid withdrawal syndrome


  1. Institute of Medicine (US) Committee on Community-Based Drug Treatment; Bridging the Gap between Practice and Research: Forging Partnerships with Community-Based Drug and Alcohol Treatment, ed. S. Lamb, M.R. Greenlick, and D. McCarty. 1998, Washington (DC): National Academies Press (US).

  2. FDA permits marketing of mobile medical application for substance use disorder. September 14, 2017, U.S. Food and Drug Administration:

  3. Campbell AN, Nunes EV, Matthews AG, Stitzer M, Miele GM, Polsky D, et al. Internet-delivered treatment for substance abuse: a multisite randomized controlled trial. Am J Psychiatry. 2014;171(6):683–90.

    Article  Google Scholar 

  4. Buck JA. The looming expansion and transformation of public substance abuse treatment under the Affordable Care Act. Health Aff. 2011;30(8):1402–10.

    Article  Google Scholar 

  5. Sarata AK. Mental health parity and the Patient Protection and Affordable Care Act of, 2010. Washington, D.C.: Congressional Research Service; 2010.

    Google Scholar 

  6. McLellan AT,  Starrels JL, Tai B, Gordon AJ, Brown R, Ghitza U, et al. Can substance use disorders be managed using the chronic care Model? Review and recommendations from a NIDA consensus Group. Public Health Rev. 2014;35(2):8.

    Article  Google Scholar 

  7. Hedegaard H, Minino AM, Warner M. Drug overdose deaths in the United States, 1999–2017. NCHS Data Brief. 2018;329:1–8.

    Google Scholar 

  8. NIDA. Overdose Death Rates. March 10, 2020; Accessed 2 Apr 2020

  9. National Center for Statistics and Analysis. (2018, October) 2017 fatal motor vehicle crashes: Overview. (Traffic Safety Facts Research Note. Report No. DOT HS 812 603). Washington, D.C.: National Highway Traffic Safety Administration.

  10. 2017 National Survey on Drug Use and Health: Detailed Tables. 2018, Substance Abuse and Mental Health Services Adminstration

  11. Woolf SH, Schoomaker H. Life Expectancy and Mortality Rates in the United States, 1959–2017. JAMA. 2019;322(20):1996–2016.

    Article  Google Scholar 

  12. Clinical guidelines for the use of buprenorphine in the treatment of opioid addiction. Center for Substance Abuse Treatment. Vol. Treatment Improvement Protocol (TIP) Series 40. HHS Publication No. (SMA) 04–3939. 2004, Rockville, MD: Substance Abuse and Mental Health Services Administration.

  13. An Introduction to Extended-Release Injectable Naltrexone for the Treatment of People With Opioid Dependence. Advisory. Vol. 11, Issue 1. 2012: Substance Abuse and Mental Health Services Administration

  14. Jones CM, Campopiano M, Baldwin G, McCance-Katz E. National and state treatment need and capacity for opioid agonist medication-assisted treatment. Am J Public Health. 2015;105(8):e55–63.

    Article  Google Scholar 

  15. Substance Abuse and Mental Health Services Administration, Center for Behavioral Health Statistics and Quality. Treatment Episode Data Set (TEDS): 2005–2015. National Admissions to Substance Abuse Treatment Services. BHSIS Series S-91, HHS Publication No. (SMA) 17–5037. 2017, Rockville, MD: Substance Abuse and Mental Health Services Administration.

  16. Boudreau DM, Lapham G, Johnson EA, Bobb JF, Matthews AG, McCormack J et al. Documented opioid use disorder and its treatment in primary care patients across six U.S. health systems. J Subst Abuse Treat. 2020;112:41–8.

    Article  Google Scholar 

  17. Morgan JR, Schackman BR, Leff JA, Linas BP, Walley AY. Injectable naltrexone, oral naltrexone, and buprenorphine utilization and discontinuation among individuals treated for opioid use disorder in a United States commercially insured population. J Subst Abuse Treat. 2018;85:90–6.

    Article  Google Scholar 

  18. Williams AR, Nunes E, Olfson M. To Battle The Opioid Overdose Epidemic, Deploy The ‘Cascade of Care’ Model, in Health Affairs Blog. 2017.

  19. Walley AY, Alperen JK, Cheng DM, Botticelli M, Castro-Donlan C, Samet JH, Alford DP. Office-based management of opioid dependence with buprenorphine: clinical practices and barriers. J Gen Intern Med. 2008;23(9):1393–8.

    Article  Google Scholar 

  20. Joudrey PJ, Edelman EJ, Wang EA. Methadone for opioid use disorder—decades of effectiveness but still miles away in the US. JAMA Psychiat. 2020;77(11):1105–6.

    Article  Google Scholar 

  21. Tofighi B, Williams AR, Chemi C, Suhail-Sindhu S, Dickson V, Lee JD. Patient barriers and facilitators to medications for opioid use disorder in primary care. Subst Use Misuse. 2019;54(14):2409–19.

    Article  Google Scholar 

  22. Lee JD, Nunes EV Jr, Novo P, Bachrach K, Bailey GL, Bhatt S, et al. Comparative effectiveness of extended-release naltrexone versus buprenorphine-naloxone for opioid relapse prevention (X:BOT): a multicentre, open-label, randomised controlled trial. Lancet. 2018;391(10118):309–18.

    Article  CAS  Google Scholar 

  23. Christie CBC, Cooper R, Kennedy PJ, Madras B, Bondi P. The President's commission on combating drug addiction and the opioid crisis. Washington, DC: The White House; 2017;‐commission/ Accessed 2 April 2020.

  24. Marsch LA, Campbell A, Campbell C, Chen CH, Ertin E, Ghitza U, et al. The application of digital health to the assessment and treatment of substance use disorders: The past, current, and future role of the National Drug Abuse Treatment Clinical Trials Network. J Subst Abuse Treat. 2020;112s:4–11.

    Article  Google Scholar 

  25. Topol E. Deep medicine: how artificial intelligence can make healthcare human again. New York: Basic Books; 2019.

    Google Scholar 

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The authors declare that they have no competing interests. All authors are employees of the Center for the Clinical Trials Network of the National Institute on Drug Abuse, the National Institutes of Health, the funding agency for the National Drug Abuse Treatment Clinical Trials Network. The opinions expressed in this manuscript are solely those of the authors and do not represent the official views of the National Institutes of Health.

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Tai, B., Dobbins, R., Blackeney, Q. et al. The NIDA clinical trials network: evolving, expanding, and addressing the opioid epidemic. Addict Sci Clin Pract 16, 28 (2021).

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