Methadone Maintenance Treatment-Related Stigma and Adherence Self-Efficacy in Vietnam

Abstract

Background:

Stigma related to methadone maintenance treatment (MMT) remains a substantial barrier to treatment engagement among people who use drugs (PWUD). Understanding how MMT-related stigma influences adherence self-efficacy is critical for supporting treatment engagement and optimizing long-term outcomes.

Objectives:

Our study examined the associations between MMT-related stigma, with a specific focus on anticipated and internalized stigma, and self-efficacy for treatment adherence among PWUD in Vietnam.

Methods:

We used cross-sectional baseline data collected between April and July 2024 from an intervention trial conducted in 3 provinces of Vietnam. Bivariate correlations and hierarchical multiple linear regression models were used to assess the relationships between 2 forms of MMT-related stigma and self-efficacy for treatment adherence, adjusting for relevant sociodemographic and background characteristics.

Results:

Among 690 PWUD participants, both anticipated MMT-related stigma (r = −.339, P < .001) and internalized MMT-related stigma (r = −.225, P < .001) were negatively correlated with self-efficacy in treatment adherence. In adjusted regression analyses that included both stigma dimensions and participants’ characteristics, only anticipated stigma remained independently associated with lower adherence self-efficacy (B = −0.198, SE = 0.031, β = −.238, P < .001).

Conclusions:

These findings underscore the importance of integrating strategies to address and reduce MMT-related stigma. Interventions that explicitly address anticipated stigma may be critical for strengthening confidence in treatment adherence and supporting sustained outcomes.

Keywords

Methadone maintenance treatment anticipated stigma internalized stigma adherence self-efficacy Vietnam

Introduction

Methadone maintenance treatment (MMT) is the most common medication-assisted treatment (MAT) for opioid dependence, reducing opioid-related harms and improving health and social well-being among people who use drugs (PWUD).^1-3 Despite strong evidence supporting the effectiveness of MMT and efforts to expand treatment access, many barriers still limit participation and retention in MMT.^4,5 To overcome individual- and structural-level barriers, PWUD must have confidence in their ability to handle challenges successfully and actively make decisions about their treatment.⁶ This underscores the importance of self-efficacy in managing addiction treatment adherence. Previous studies have shown that higher self-efficacy is related to treatment adherence, healthier lifestyle changes, and the development of management and coping skills for chronic health problems.^7,8 Despite its theoretical and practical importance, treatment adherence self-efficacy among PWUD, particularly in relation to MMT, remains insufficiently examined.

Previous studies on self-efficacy have largely focused on people with chronic health conditions and identified several factors associated with self-efficacy, including education level, gender, occupational status, psychological health, and family and social support.^9-12 However, PWUD face distinct challenges that may undermine self-efficacy, particularly stigma related to both substance use and addiction treatment.^13-17 Prior studies have documented associations between stigma and self-efficacy among PWUD.^18-20 But less is known about how stigma is associated with MMT, particularly anticipated stigma and internalized stigma related to being identified as an MMT patient, and how that shapes treatment adherence self-efficacy. Clarifying this relationship is essential for improving the effectiveness of MMT programs.^21,22

Vietnam provides an important context in which to examine these dynamics. Since being piloted in 2008 as a harm reduction response to HIV transmission associated with injection drug use, MMT has been scaled up nationwide and is now the primary treatment for opioid use disorder.²³ The expansion of MMT is part of a broader effort to shift from compulsory addiction treatment toward voluntary, evidence-based, and community-based approaches. Nevertheless, this transition has faced persistent challenges, including limited social acceptance of addiction treatment and stigma toward both substance use and methadone therapy.^24-27 In a sociocultural context strongly shaped by traditional norms, MMT-related stigma may impact confidence in treatment adherence and increase the risk of treatment interruption or dropout. To address these gaps, the present study examined the relationship between MMT-related stigma and treatment adherence self-efficacy among PWUD in Vietnam, with a specific focus on anticipated and internalized stigma.

Methods

Participants and Data Collection

This study used data collected at baseline from a randomized controlled intervention trial in Vietnam.²⁸ Data were collected between April and July 2024 in communities (ie, communes, or “xã” in the Vietnamese context) across 3 provinces: Ninh Binh, Da Nang, and Can Tho. To select communities, in each province, we first made a list of communities and ranked them from highest to lowest based on the number of PWUD. We then selected the communities with the highest number of PWUD to make sure we had enough participants. The number of communities selected in each province was 28 in Ninh Binh, 14 in Da Nang, and 16 in Can Tho, with a total of 58 communities included. Participants were Vietnamese people who use drugs (PWUD) living in the selected communities and were eligible if they met the following criteria: (1) were 18 years of age or older; (2) had a history of drug use; (3) had disclosed their drug use to at least 1 family member and invited that family member to take part in the study; (4) were current residents of the selected communities; and (5) provided informed consent. Of those eligible, 85% of PWUDs agreed to participate, resulting in 690 participants in total.

All participants gave written informed consent prior to study enrollment. They completed the questionnaires in a private setting, either at a local community health center or a chosen location. Trained interviewers carried out individual, face-to-face interviews using a Computer-Assisted Personal Interview (CAPI) system, with responses entered directly into password-protected laptop computers. All interviews were conducted in Vietnamese, and each assessment lasted approximately 45 minutes. Participants were compensated with 230 000 Vietnamese dong (VND), approximately USD 8.75, for their time and effort.

Measures

Adherence self-efficacy was measured using an adapted version of the HIV Treatment Adherence Self-Efficacy Scale (HIV-ASES), a validated instrument with demonstrated reliability and validity in HIV treatment adherence.²⁹ Given conceptual similarities in adherence challenges faced by people living with HIV and PWUD, particularly in contexts where stigma, chronic care needs, and psychological strain are present, this scale was adapted and used in our study. Participants were asked how confident they were in performing 8 activities, for instance “Stick to your treatment schedule even when your daily routine is disrupted,” “Stick to your treatment schedule even if your friends may tell you not to do so,” “Continue with your treatment even when you are feeling discouraged about your health,” or “Continue with your treatment even when people close to you do not think that it is doing any good.” The response categories ranged from 0 “Not confident at all” to 2 “Very confident.” Evidence from pilot testing with PWUD in Vietnam during the early phase of the parent trial demonstrated that the adapted 8-item scale had good validity and reliability for measuring adherence self-efficacy in the current study sample (Supplemental Material). An overall adherence self-efficacy score (range: 0-16) was calculated by summing all items, with higher scores indicating greater self-efficacy for treatment adherence (Cronbach’s α = .98).

Methadone Maintenance Treatment (MMT)-related stigmas were assessed using adapted subscales of the Methadone Maintenance Treatment Stigma Mechanisms Scale (MMT-SMS).³⁰ The original scale has 25 items with 3 subscales measuring anticipated stigma, enacted stigma, and internalized stigma across multiple sources (family, healthcare workers, and employers). To examine stigmas closely related to psychological processes and treatment engagement, we assessed anticipated stigma and internalized stigma.^31,32 Pilot testing was conducted among PWUD in Vietnam during the early phase of the parent randomized trial to ensure the cultural relevance and contextual appropriateness of all 12 items in the adapted scale. The results also showed adequate validity and reliability of the scale for assessing anticipated and internalized MMT-related stigma in the study (Supplemental Material). Participants indicated their degree of agreement with each statement (ranging from 1 “strongly disagree” to 5 “strongly agree”). Anticipated MMT-related stigma was measured using 6 items. Example items include: “Family members will think that I am still a drug user,” “Family members will not support my methadone treatment,” “Healthcare workers will not prescribe me medication that I need.” A score is calculated by summing all items (range: 6-30). A higher score indicated a higher level of anticipated stigma (Cronbach’s α = .77). Internalized MMT-related stigma was evaluated by a 6-item scale. Example items include: “Receiving methadone makes me feel like I am a bad person,” “I feel ashamed of my methadone treatment,” “Being on methadone treatment makes me feel like I am still a drug user.” The items were summed to create a total internalized stigma score (range: 6-30), with higher scores reflecting a higher level of internalized stigma (Cronbach’s α = .92).

We also collected data on participants’ background characteristics, including sex (male vs female), age, education years (total number of years of formal education completed), marital status (married or living as married vs not), current employment status (currently employed vs not), types of substances used, self-rated overall health status (good vs not good - fair/poor), and whether they are currently receiving MMT (yes vs no).

Data Analysis

Descriptive statistics were used to summarize participants’ background characteristics and scores for adherence self-efficacy, anticipated MMT-related stigma, and internalized MMT-related stigma. Categorical variables were reported as frequencies (n) and percentages (%), and continuous variables were presented as means and standard deviations (SD). Given the normal distribution of scale scores, we applied t-tests and one-way analyses of variance (ANOVAs) to examine differences in scale scores across participants’ characteristics.

Pearson correlation coefficients were calculated to assess the associations between 2 types of MMT-related stigma measures (anticipated stigma and internalized stigma) and adherence self-efficacy. We reported both the correlation coefficient (r) and the p-value. Then, hierarchical multiple linear regression models were conducted. In the first step, background characteristics were entered into the model. In the second step, anticipated MMT-related stigma and internalized MMT-related stigma were included. Unstandardized regression coefficients (B), standard errors (SE), estimated regression coefficients (β), and p-values were reported, with statistical significance set at α = 0.05. To evaluate the potential impact of multicollinearity, we analyzed the Variance Inflation Factor (VIF) and tolerance (1/VIF) for all independent variables in the final models. A VIF < 4 and tolerance > 0.20 were considered to indicate no multicollinearity concerns.³³ All statistical analyses were performed using STATA software, version 17.1 MP (StataCorp LLC, College Station, TX).

Results

Table 1 summarizes participants’ demographic characteristics, self-rated health status, and current MMT status. Of 690 participants, most were male, aged 36 to 45, with less than 10 years of education. Most participants reported lifetime opioid use (94.1%), followed by sedatives or sleeping pills (7.4%) and amphetamine-type stimulants (6.9%). About 57.8% described their overall health as good. The percentage of PWUD currently on MMT was 77.8%.

Table 1.

Descriptive Characteristics of Participants (n = 690).

Characteristics	n orM (SD)	%	Internalized MMT-related stigma		Anticipated MMT-related stigma		Adherence self-efficacy
Characteristics	n orM (SD)	%	M (SD)	p-value	M (SD)	p-value	M (SD)	p-value
Total	690	100.0	12.5 (5.0)		11.7 (5.1)		13.4 (4.2)
Sex
Female	22	3.2	13.0 (5.5)	.643	14.0 (5.3)	.036	12.5 (4.6)	.335
Male	668	96.8	12.5 (5.0)		11.7 (5.0)		13.4 (4.2)
Age	42.2 (8.8)
18-35	144	20.9	13.0 (5.1)	.281	12.7 (4.9)	.025	12.4 (4.6)	<.001
36-45	338	49.0	12.2 (4.8)		11.4 (5.0)		13.3 (4.2)
46 and above	208	30.1	12.6 (5.3)		11.5 (5.2)		14.2 (3.8)
Education years	8.8 (3.3)
5 y or fewer	99	14.3	13.3 (5.2)	.070	12.8 (5.6)	.003	13.6 (4.2)	.681
6-9 y	317	46.0	12.7 (5.2)		12.0 (5.2)		13.2 (4.2)
10 y or more	274	39.7	12.1 (4.7)		11.0 (4.6)		13.4 (4.2)
Married/living as married
Yes	399	57.8	12.5 (5.1)	.925	11.2 (4.8)	.003	13.6 (4.2)	.045
No	291	42.2	12.5 (4.9)		12.4 (5.3)		13.0 (4.2)
Currently employed
Yes	542	78.6	12.6 (5.0)	.358	11.7 (5.0)	.949	13.3 (4.2)	.798
No	148	21.4	12.2 (5.2)		11.7 (5.2)		13.4 (4.3)
Self-rated health status
Good	399	57.8	12.0 (5.0)	.002	11.4 (4.8)	.044	13.6 (3.9)	.121
Not good	291	42.2	13.2 (4.9)		12.2 (5.4)		13.1 (4.6)
Currently on MMT
Yes	537	77.8	11.9 (4.7)	<.001	11.1 (4.7)	<.001	14.2 (3.3)	<.001
No	153	22.2	14.8 (5.5)		13.9 (5.7)		10.5 (5.6)

M: Mean; SD: Standard deviation.

Bivariate correlations between MMT-related stigma and adherence self-efficacy across participants’ characteristics are presented in Table 2. As shown, anticipated MMT-related stigma was negatively associated with self-efficacy in treatment adherence (r = −.339, P < .001). People reporting higher levels of internalized MMT-related stigma were more likely to have lower levels of adherence self-efficacy (r = −.225, P < .001). Anticipated and internalized stigma were also correlated (r = .373, P < .001). Having a good self-rated health status was only negatively correlated with both measured dimensions of MMT-related stigma. While being currently on MMT was positively related to adherence self-efficacy (r = .357, P < .001), it was negatively correlated with anticipated (r = −.229, P < .001) and internalized MMT-related stigma (r = −.240, P < .001).

Table 2.

Correlation Coefficients and Significant Levels Among Selected Variables (n = 690).

Variables	Adherence self-efficacy	Anticipated MMT-related stigma	Internalized MMT-related stigma
Anticipated MMT-related stigma	−0.339***	1
Internalized MMT-related stigma	−0.225***	0.373***	1
Male	0.037	−0.080*	−0.018
Age	0.138***	−0.075*	−0.006
Married/living as married	0.077*	−0.115**	−0.004
Education years	−0.012	−0.128**	−0.096*
Currently employed	−0.010	0.002	0.035
Good self-rated health status	0.059	−0.077*	−0.118**
Currently on MMT	0.357***	−0.229***	−0.240***

P < .05; ** P < .01; *** P < .001.

Table 3 presents the hierarchical multiple linear regression model adjusted for covariates. No evidence of multicollinearity was detected, as VIF values ranged from 1.01 to 1.23 and all tolerance values exceeded 0.2. The results show that anticipated MMT-related stigma remained significantly associated with adherence self-efficacy (B = −0.198, SE = 0.031, β = −.238, P < .001). Internalized MMT-related stigma was not significantly related to adherence self-efficacy in the final model (B = −0.052, SE = 0.031, β = −.061, P = .101). People who are older (B = 0.054, SE = 0.007, β = .113, P = .002) or who perceive their health as good (B = 0.709, SE = 0.299, β = .083, P = .018) were more likely to report higher levels of adherence self-efficacy than others. Being currently on MMT was associated with a higher level of self-efficacy in treatment adherence compared to not currently being on MMT (B = 2.970, SE = 0.361, β = .293, P < .001).

Table 3.

Hierarchical Multiple Regression Model to Explore the Relationship Between MMT-Related Stigma and Adherence Self-Efficacy (n = 690).

Factors	Adherence self-efficacy
	Model 1					Model 2
	B	SE	β	p	B	SE	β	p
Male (vs. Female)	0.768	0.845	0.032	.364	0.340	0.816	0.014	.677
Age	0.062	0.018	0.129	.001	0.054	0.017	0.113	.002
Married/living as married (vs. No)	0.365	0.314	0.043	.245	0.170	0.304	0.020	.576
Education years	−0.029	0.045	−0.023	.516	−0.070	0.044	−0.055	.110
Currently employed (vs. No)	0.005	0.369	0.001	.989	0.0632	0.356	0.006	.859
Good self-rated health (vs. No)	1.007	0.307	0.118	.001	0.709	0.299	0.083	.018
Currently on MMT (vs. No)	3.679	0.358	0.363	<.001	2.970	0.361	0.293	<.001
Anticipated MMT-related stigma					−0.198	0.031	−0.238	<.001
Internalized MMT-related stigma					−0.052	0.031	−0.061	.101
R²	0.159				0.222
ΔR² (Model 2 – Model 1)					0.063
F-change test (p-value)					27.464 (<0.001)

B: Unstandardized coefficient; SE: Standard error; β: Standardized coefficient; p: p-value.

Discussion

In this study, we found that MMT-related stigma, specifying anticipated and internalized stigma, was negatively correlated with treatment adherence self-efficacy among PWUD in Vietnam. We also observed that the strength of this association differed by stigma dimension, with anticipated stigma demonstrating a more robust relationship with adherence self-efficacy than internalized stigma. These findings reinforce the understanding that stigma is not only a social experience but also a psychological barrier that may undermine confidence in initiating and sustaining engagement in addiction treatment. As such, efforts to improve adherence should extend beyond the individual to address stigma embedded within families, healthcare settings, and broader community environments. The results also underscore that it is crucial to develop targeted interventions that boost PWUD’s confidence in MMT adherence and results.

Our study findings add to the existing literature on adherence self-efficacy and the influence of stigma on engagement and retention in treatment.^16,17,19,22 In Vietnam, drug use is commonly perceived as both a moral failing and a criminal behavior, contributing to enduring stigma toward both addiction and its treatment.^24,34 This perception may force many PWUD to conceal their treatment status from family members, employers, and the broader community.^26,27,35 Given that self-efficacy is a key determinant of health behaviors, especially in long-term and highly structured treatments such as MMT,⁷ exposure to stigmatizing attitudes and anticipated negative reactions may undermine their belief in and confidence in their ability to adhere to treatment requirements. Therefore, strategies aimed at increasing adherence self-efficacy and improving MMT outcomes should incorporate treatment-related stigma reduction, psychosocial support, and patient empowerment into the MMT programs. Several approaches may help reduce treatment-related stigma, such as educating patients, families, and communities, and training healthcare staff to communicate respectfully and without judgment. To strengthen psychosocial support in MMT programs, it is necessary to develop counseling services, peer support groups, and family involvement. In addition, improving patient knowledge, encouraging participation in treatment decisions, and improving communication between patients and providers can promote PWUD’s confidence. Together, these approaches may improve adherence self-efficacy and overall MMT treatment outcomes.

Our study showed that anticipated MMT-related stigma remained significantly associated with adherence self-efficacy after controlling for sociodemographic and treatment-related factors, whereas internalized stigma did not. Previous studies examining the relationship between anticipated stigma and adherence self-efficacy have reported inconsistent findings, potentially reflecting differences in study populations, settings, and measurement approaches.^36-38 Several explanations may account for the stronger role of anticipated stigma observed in our study. First, anticipated stigma reflects expectations of future discrimination or judgment from others, which may have a more immediate and direct impact on day-to-day treatment behaviors, such as clinic attendance and medication adherence.³¹ Second, in the Vietnamese context, where PWUD must navigate complex social relationships with family members, peers, healthcare providers, and the broader community, concerns about negative stereotypes related to addiction treatment may be especially relevant.^15,16,24,35 As a result, fear of disclosure and potential social consequences may outweigh self-directed negative beliefs in shaping adherence-related confidence. Finally, internalized MMT-related stigma may influence adherence self-efficacy more indirectly through other psychological factors, which were not examined in the present analysis and warrant further investigation. These findings suggest that reducing anticipated MMT-related stigma and fostering supportive environments will be especially effective in strengthening adherence self-efficacy.

Several limitations should be considered when interpreting these findings. Because the study was cross-sectional, we cannot determine causal or temporal relationships between internalized and anticipated MMT-related stigma and adherence self-efficacy. As the data were collected using self-report measures, sensitive information, such as types of substance used and history of opioid use, may be subject to recall bias or inaccurate reporting. We did not assess several potentially relevant factors, for instance, psychological characteristics and assessment, which limit our ability to more fully explore the mechanisms through which different forms of MMT-related stigma may affect adherence self-efficacy.

Conclusions

Our findings revealed that MMT-related stigma was negatively associated with treatment adherence self-efficacy among PWUD in Vietnam, with anticipated stigma showing a stronger and more robust effect than internalized stigma. These findings highlight the need for MMT programs to address treatment-related stigma, particularly fears of judgment and discrimination from others, to strengthen confidence in adherence and support sustained treatment outcomes. To achieve this goal, healthcare staff not only in MMT programs but also in the general healthcare system should be trained to communicate respectfully and without judgment with PWUD. In addition, community education can help people better understand MMT and reduce negative attitudes toward it. It is also important to create a friendly and private clinic environment, involve patients, and provide opportunities for PWUD to take a more active role in treatment decisions.

Supplemental Material

sj-docx-1-sat-10.1177_29768357261452223 – Supplemental material for Methadone Maintenance Treatment-Related Stigma and Adherence Self-Efficacy in Vietnam

Supplemental material, sj-docx-1-sat-10.1177_29768357261452223 for Methadone Maintenance Treatment-Related Stigma and Adherence Self-Efficacy in Vietnam by Hieu Ngoc Nguyen, Li Li, Tuan Anh Nguyen and Thang Hong Pham in Substance Use: Research and Treatment

Footnotes

Acknowledgements

We would like to express our gratitude to the participants in this study and to gratefully acknowledge our Vietnamese project team members in Hanoi, Ninh Binh, Da Nang, and Can Tho provinces for their contributions to this study.

ORCID iDs

Hieu Ngoc Nguyen

Li Li

Ethical Considerations

The study was approved by the Institutional Review Board of the University of California, Los Angeles (UCLA IRB-23-1845-CR-001) on January 24, 2025, and the Institutional Review Board in Bio-Medical Research, National Institute of Hygiene & Epidemiology in Vietnam (NIHE IRB VN01057/IORG 0008555; No: HDDD - 26/2024) on December 31, 2024. All participants in formative research procedures provided written informed consent.

Consent to Participate

All participants in formative research procedures provided written informed consent.

Author Contributions

HNN: Conceptualization, methodology, formal analysis, writing - original draft, writing - review & editing; LL: Conceptualization, methodology, writing - original draft, writing - review & editing, supervision, resources, project administration, funding acquisition; TAN: Writing - review & editing, investigation, supervision, project administration, funding acquisition; THP: Writing - review & editing, supervision, project administration.

Funding

The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was supported by the National Institute on Drug Abuse of the National Institutes of Health (NIH) under award number [R01DA050678]. The content is solely the responsibility of the authors and does not necessarily represent the views of the NIH.

Declaration of Conflicting Interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Supplemental Material

Supplemental material for this article is available online.

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