The starting point for the correspondence is a 2025 study by Campbell and colleagues, also published in the Journal of General Internal Medicine, which examined the impact of substance use navigators on two outcomes of obvious clinical and economic importance: initiation of treatment for substance use disorders and 30-day unplanned hospital readmission. Navigators in such models typically meet patients during or shortly after an emergency department visit, establish rapport, address practical barriers such as insurance, transportation, and appointment scheduling, and maintain follow-up contact until the patient is connected with medication for opioid use disorder, counseling, or other formal treatment. The Campbell study reported on the program’s overall effect, and the new letter by Luo and Song accepts the value of that contribution while arguing that the field now needs to ask finer-grained questions about mechanism and equity.

The first of those questions concerns dose-response. In epidemiology and clinical research, a dose-response relationship describes how an outcome changes as the level of exposure increases—in this case, how the number, duration, or intensity of navigator interactions relates to the probability that a patient initiates treatment or avoids an early readmission. Luo and Song argue that establishing such a relationship matters for more than statistical completeness. If treatment initiation rises steadily with each additional navigator contact, that pattern would support a causal interpretation of the navigator’s role and would give program designers an empirical basis for setting contact targets. If instead the relationship plateaus or is non-linear, with most benefit accruing in the first few encounters, health systems could allocate scarce navigator time more efficiently, concentrating intensive outreach on the patients who need it rather than spreading effort uniformly.

The letter situates this argument within modern causal thinking. Luo and Song cite work by Shimonovich and colleagues in the European Journal of Epidemiology that revisits the classic Bradford Hill considerations for assessing causality in epidemiology in light of contemporary developments in causal inference. That framework emphasizes that consistency, biological or mechanistic plausibility, and dose-response gradients are suggestive but not decisive on their own, and that observational findings must be interpreted with explicit attention to confounding and selection. Applied to navigator research, the implication is that a simple before-and-after comparison of treatment initiation rates cannot settle whether navigators caused the improvement, because patients who receive more navigator contact may differ systematically from those who receive less—in motivation, housing stability, insurance status, or severity of illness. Dose-response analysis, the letter suggests, is one tool among several for strengthening causal interpretation, provided it is designed with those confounders in view.

The second axis of the letter concerns socioeconomic factors. Luo and Song highlight that the effectiveness of a navigator program cannot be fully understood without attending to the social and economic circumstances of the patients it serves. Substance use disorders are strongly patterned by socioeconomic position: housing instability, unemployment, low educational attainment, lack of insurance, and limited access to transportation all raise the barriers between a patient in an emergency department and a functioning treatment linkage. A navigator intervention that appears uniformly effective in an aggregate analysis may in fact work well for some patient subgroups and poorly for others, and the letter argues that exploring these heterogeneities is essential both for scientific understanding and for equitable program design.

Support for this concern comes from a broader literature that the letter references. Birkeland and colleagues, writing in Addiction Science and Clinical Practice, examined perceived family cohesion, social support, and quality of life among patients undergoing treatment for substance use disorders, comparing them with patients treated for mental and physical disorders. Their findings underscore that social resources are not peripheral to addiction treatment but intertwined with how patients experience and sustain it. For navigators, this literature suggests that the same dose of navigator contact may translate into different outcomes depending on the family, community, and economic context surrounding each patient. A patient with stable housing and supportive family members may need relatively brief navigation to reach treatment, while a patient facing homelessness or isolation may require sustained, resource-intensive engagement that standard program protocols were not designed to provide.

The practical implications of the letter’s argument extend to how navigator programs are evaluated. Randomized trials and quasi-experimental studies of navigation have generally reported average effects across enrolled populations, and those averages have informed decisions by hospital systems and policymakers. Luo and Song’s point is that averages can conceal the dose-response structure and the socioeconomic gradient that actually determine a program’s real-world performance. An evaluation that records the number and duration of navigator contacts, stratifies outcomes by measures of socioeconomic position, and models the interaction between the two would give administrators actionable information: which patients to prioritize, how many contacts to budget for, and where supplementary social services—housing assistance, benefits enrollment, peer support—would complement navigation most effectively.

The letter also speaks to a tension familiar in implementation science: the trade-off between fidelity to a tested model and adaptation to local conditions. Navigator programs originated in cancer care and have been adapted for HIV, mental health, and substance use, with each adaptation altering the intensity and scope of the role. If dose-response analysis shows that early contacts carry most of the benefit, programs might reasonably front-load engagement in the first days after an emergency visit. If socioeconomic stratification shows that disadvantaged patients derive equal or greater benefit from extended navigation, then uniform staffing models that cap contact time may systematically underserve the patients with the greatest need. In either scenario, the letter’s framework converts a general endorsement of navigation into specific, testable design parameters.

It is worth noting the limits of what the letter itself establishes. As a correspondence item, it does not present new patient data, and its authors report no funding and declare no conflicts of interest. Its contribution is to set an agenda: future studies of substance use navigators, the authors argue, should be designed from the outset to capture contact intensity and socioeconomic context, rather than treating navigation as an undifferentiated exposure. The citation of Bradford Hill–informed causal reasoning signals that the authors want the field to move beyond association toward defensible causal claims, using designs such as stratified analyses, sensitivity analyses for unmeasured confounding, and, where feasible, randomized variation in navigator dosage.

For clinicians and health system leaders, the message is that the navigator model has earned its place in the response to substance use disorders, but that its next phase of development depends on finer measurement. The questions Luo and Song raise—how much contact is enough, for whom, and under what social conditions—are precisely the questions that determine whether navigation becomes a durable, scalable component of addiction care or a promising intervention whose benefits erode as it spreads. The letter, published as part of the Journal of General Internal Medicine’s correspondence section, is likely to shape the design of the next generation of navigator evaluations, and its emphasis on dose and equity reflects a broader shift in health services research toward understanding not just whether interventions work, but how and for whom.

Subject of Research: Dose-response relationships and socioeconomic factors in substance use navigator programs for addiction treatment linkage

Article Title: Enhancing the Impact of Substance Use Navigators: Exploring Dose-Response Relationships and Socioeconomic Factors

Article References: Luo, J., & Song, Y. (2026). Enhancing the Impact of Substance Use Navigators: Exploring Dose-Response Relationships and Socioeconomic Factors. Journal of General Internal Medicine. https://doi.org/10.1007/s11606-026-10813-9

Image Credits: AI Generated

DOI: 10.1007/s11606-026-10813-9

Keywords: substance use navigators, dose-response, socioeconomic factors, emergency department, treatment initiation, hospital readmission, causal inference, Bradford Hill, health equity, addiction medicine, Journal of General Internal Medicine, implementation science

Buprenorphine is one of three drugs approved by the US Food and Drug Administration for long-term treatment of opioid use disorder, and it is widely regarded as among the most effective and accessible options. The medication works by reducing cravings and easing withdrawal symptoms, which in turn lowers the risk of overdose. It occupies opioid receptors in the brain in a way that blunts the euphoric effects of other opioids while preventing the physical agony of withdrawal, allowing patients to stabilize their lives and remain engaged in care. Unlike some other treatments, buprenorphine can now be prescribed in doctor’s offices and pharmacies, following a December 2025 law intended to expand access, a shift that matters enormously as fentanyl, which is up to 50 times stronger than heroin, continues to drive the opioid overdose epidemic across the United States.

Pregnancy, however, fundamentally changes how the body handles this medication. Physical and hormonal changes accelerate the metabolization of buprenorphine in pregnant patients, meaning that higher doses are often required for them to avoid withdrawal. This is not a marginal effect: data suggest that up to 90 percent of pregnant women with opioid use disorder require higher doses of the drug. The problem is compounded by the fentanyl era, since increased doses are often necessary even for people who are not pregnant to adequately counteract the potency of illicit synthetic opioids. A typical daily dose of buprenorphine administered under the tongue begins at 2 to 4 milligrams, with the standard target dosage reaching 16 to 24 milligrams, though some patients can benefit from doses up to 32 milligrams.

Despite a growing body of research supporting increased dosages as clinically needed, buprenorphine treatment during pregnancy remains inconsistent, and patients frequently receive inadequate amounts of the medication. Clinical guidelines on dosing for pregnant and postpartum patients are vague and offer little direction on dose adjustment. State Medicaid policies often go further still, capping doses in ways that are not grounded in the evidence. In some states, pregnancy guidance around buprenorphine includes language that implies dose minimization should be the goal, an approach that contradicts decades of evidence about the clinical needs of pregnant patients with opioid use disorder.

Dr. Morgan, a research assistant professor of health law, policy and management at Boston University School of Public Health, has built his career around the opioid overdose epidemic and the question of how to improve access to and retention on medications for opioid use disorder. He argues that the gap between what the evidence shows and what policy allows is both wide and consequential. Pregnant women generally metabolize drugs differently than non-pregnant individuals due to the profound physiological changes of gestation, and the failure to adjust dosing accordingly can push patients into withdrawal, a condition that carries serious risks for both mother and fetus and that frequently drives people back to illicit opioid use.

Dr. Leech, an assistant professor of health policy at Vanderbilt University School of Medicine, points to a phenomenon known as therapeutic inertia as a key driver of dangerous underdosing. In pregnancy, clinical uncertainty and concerns about fetal safety can make clinicians reluctant to increase medication doses even when the evidence supports doing so. The result is a system in which pregnant patients may be left under-treated at precisely the moment when stable, sustained treatment matters most, both for their own health and for the health of their babies. Her work focuses on how coverage decisions and policy design shape real-world treatment patterns and outcomes.

The new study will concentrate on pregnant women covered by Medicaid, a population that is central to this public health challenge. State Medicaid programs cover more than 80 percent of pregnant women with opioid use disorder in the United States, which makes Medicaid dosing policies a decisive lever in whether these patients receive adequate care. Yet many Medicaid programs cap daily dosages of buprenorphine, and some states actively discourage physicians from increasing the dosage during a patient’s pregnancy. The researchers will collaborate with investigators from Boston Medical Center to assess national and state-level differences in buprenorphine dosing between pregnant and non-pregnant women with opioid use disorder, examining how dosing patterns have evolved over time and in response to the spread of fentanyl.

Beyond documenting these patterns, the team will examine the effectiveness of different buprenorphine dosage thresholds and how those dosages advance or inhibit sustained treatment. Retention in treatment is one of the most important predictors of outcomes in opioid use disorder, since patients who discontinue medication face sharply elevated risks of relapse and overdose. Understanding whether higher doses keep pregnant patients engaged in care longer, and whether inadequate doses push them toward treatment discontinuation, could reshape clinical practice and coverage policy alike. The researchers will also estimate the long-term health and economic consequences of suboptimal dosing by applying a decision analytic model capable of projecting multiple outcomes among pregnant and postpartum women with opioid use disorder, including treatment discontinuation, postpartum treatment continuation, overdose, infant outcomes, life expectancy, and healthcare utilization, as well as the cost-effectiveness of restricting or increasing Medicaid dosing limits.

Decision analytic modeling occupies a distinctive niche in health services research because it allows investigators to quantify outcomes that would be infeasible or unethical to assess in clinical trials. As Dr. Leech explains, the approach can leverage existing evidence on dosing effects to project outcomes such as maternal and infant lives lost and the long-term costs of untreated opioid use disorder or suboptimal care, providing a rigorous method for comparing the tradeoffs of different coverage decisions. Rather than waiting years for observational data to accumulate, policymakers could use these projections to weigh the consequences of dose caps against the benefits of more generous dosing thresholds, with estimates spanning both health effects and budget impacts.

For the research team, the ultimate ambition is to translate a technical dosing question into a policy and ethical imperative. By demonstrating that higher buprenorphine dosing during pregnancy improves maternal and infant outcomes and is cost-effective, Dr. Morgan and Dr. Leech hope to give state Medicaid programs and clinical guideline writers the evidence they need to abandon dose minimization policies and embrace dosing strategies grounded in the realities of pregnancy metabolism and the fentanyl-dominated drug supply. If successful, the five-year project could help ensure that one of the most effective tools against the opioid epidemic finally works as well for pregnant women as it does for everyone else, turning a preventable source of maternal and infant harm into an opportunity for meaningful public health gains.

Subject of Research: Effectiveness and health-economic consequences of higher-dosage buprenorphine treatment for pregnant women with opioid use disorder

Article Title: Professors receive $3.7 million NIH grant to study effectiveness of higher-dosage buprenorphine among pregnant women with opioid use disorder

Article References: Professors receive $3.7 million NIH grant to study effectiveness of higher-dosage buprenorphine among pregnant women with opioid use disorder. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: buprenorphine, opioid use disorder, pregnancy, Medicaid, NIH grant, maternal health, fentanyl, health policy, decision analytic modeling, overdose prevention, Boston University, Vanderbilt University

The research team, led by Justin Berk of Alpert Medical School at Brown University and the Center for Health and Justice Transformation, focused on a system that has become a national reference point. The Rhode Island Department of Corrections is a unified state system housing both pretrial and sentenced individuals, and it has operated one of the longest-running medications for opioid use disorder programs in the United States, in place since 2016. That longevity made it an ideal setting to ask a question that clinical trials rarely capture: what does medication-assisted treatment actually do to the daily workings of a correctional institution over years of implementation?

Methodologically, the study relied on semi-structured qualitative interviews with nineteen incarcerated individuals and ten correctional and medical facility staff. The interviews explored the cultural and operational context of medication implementation, including experiences with extended-release injectable buprenorphine, a long-acting formulation administered monthly that has become increasingly important in correctional settings. All interviews were audio-recorded and transcribed, and the researchers analyzed them using applied thematic analysis, a systematic qualitative method that identifies recurring patterns of meaning across participant accounts. The study received approval from the Brown University Health Institutional Review Board and the Rhode Island Department of Corrections Medical Research Advisory Group, and all participants provided written informed consent.

Three major themes emerged from the analysis, and the first concerns what researchers call facility climate. Participants perceived that the availability of opioid use disorder medications reduced contraband drug use, violence, and disciplinary infractions within the facilities. This is a significant finding because contraband opioids, particularly illicit fentanyl, have become a central security and public health threat in jails across the country. When incarcerated people can obtain evidence-based treatment that relieves cravings and prevents withdrawal, the black-market demand that drives smuggling, debt, and violence may shrink. Interviewees also described improvements in social functioning, including greater participation in court proceedings and rehabilitative programming, suggesting that stabilized patients engage more constructively with the legal and institutional processes they must navigate.

The second theme directly addresses the objection most often raised by skeptics of prison-based addiction treatment: diversion, the practice of saving or trading medication doses for other purposes. Diversion did occur in the Rhode Island system, participants reported, often to get high or to manage withdrawal symptoms. But interviewees perceived it as limited in scope, and most patients were perceived to use their medications as prescribed. Importantly, participants emphasized that diversion is not unique to opioid treatment medications; it also occurs with other prescribed drugs in correctional settings. From a security-management perspective, this reframes diversion from a disqualifying danger into a routine, manageable clinical and operational problem comparable to those already handled with other medications every day.

Extended-release injectable buprenorphine emerged as a particularly effective tool in this regard. Because the medication is a monthly depot injection administered under clinical supervision rather than a daily tablet that passes through many hands, it was widely regarded by participants as a strategy that reduces both diversion risk and operational burden. Daily observed dosing of medication is labor-intensive for medical staff and creates choke points that custody staff must manage; a monthly injection collapses that logistical challenge. For administrators weighing the costs of running a medication program, the injectable formulation appears to offer a practical compromise that preserves clinical benefit while addressing the security concerns that most commonly stall implementation.

The third theme is the most culturally revealing: even in a system with nearly a decade of continuous program operation, stigma toward these medications persisted among some custody staff and some incarcerated peers. Skepticism about whether opioid agonist treatment constitutes real recovery, or whether it merely substitutes one drug for another, remains a durable cultural artifact within corrections. The study identifies education and leadership support as the critical levers for overcoming this resistance. Programs that invested in training and in visible, sustained buy-in from leadership were better positioned to convert skeptics and to integrate addiction treatment into the institutional identity rather than treating it as an exception or an imposition.

Notably, the researchers found that medication implementation created opportunities for improved collaboration between medical and security staff, even though some tensions remained. In many facilities, healthcare units and custody operations function as parallel hierarchies with different priorities: one oriented toward health, the other toward order. A shared program like medications for opioid use disorder forces the two sides into regular coordination, from dosing logistics to responding to diversion incidents, and participants described how this contact could build mutual understanding. The tensions that persisted did not disappear, but the study suggests the medication program itself can serve as a structure through which interdisciplinary working relationships develop.

The implications extend well beyond Rhode Island. Most jails and prisons in the United States still do not offer all three FDA-approved medications for opioid use disorder, and diversion fears remain the most commonly cited barrier. People leaving incarceration face a dramatically elevated risk of fatal overdose in the days and weeks after release, a phenomenon documented repeatedly in the public health literature, because tolerance lost during abstinence meets unchanged patterns of use. Treatment that begins inside and continues after release is among the strongest known protective factors. If implementing such treatment also reduces violence and disciplinary problems inside, as this study’s participants perceived, then the institutional case for medication programs becomes considerably harder to dismiss on purely administrative grounds.

The authors caution, appropriately, that these are perceptions gathered from a single state system with an unusually mature program, and qualitative findings describe lived experience rather than measuring outcomes directly. But the study’s conclusions are clear and actionable: medications for opioid use disorder in correctional settings can support a safer, more stable facility environment, diversion concerns appear manageable and comparable to those of other medications, and programs that invest in education, leadership engagement, and medical-security partnerships are best positioned to overcome resistance. For a nation whose jails have become de facto frontline institutions of the overdose crisis, the Rhode Island experience suggests that the contraband-versus-medicine debate may finally be resolving in favor of medicine, and that the benefits flow to security officers, medical staff, incarcerated people, and the communities they return to alike.

Subject of Research: Qualitative study of how medications for opioid use disorder reshape culture, operations, and safety in correctional facilities

Article Title: From contraband to collaboration: a qualitative study of how medications for opioid use disorder can reshape correctional culture and safety

Article References: Berk, J., Martin, M., Cook, M., Miller, C., Suh, M., Murphy, C., Jack, H. E., Rich, J. D., Brinkley-Rubinstein, L., & Guthrie, K. M. (2026). From contraband to collaboration: a qualitative study of how medications for opioid use disorder can reshape correctional culture and safety. BMC Public Health. https://doi.org/10.1186/s12889-026-29554-9

Image Credits: AI Generated

DOI: 10.1186/s12889-026-29554-9

Keywords: opioid use disorder, medications for opioid use disorder, buprenorphine, correctional health, jails and prisons, diversion, harm reduction, implementation science, qualitative research, overdose prevention, correctional culture, public health