Social and structural barriers for adherence to methadone maintenance treatment among Vietnamese opioid dependence patients
Social and structural barriers for adherence to methadone maintenance treatment among Vietnamese opioid dependence patients
Bach Xuan Tran 0 1
Long Hoang Nguyen 1
Tung Thanh Tran 1
Carl A. Latkin 1
☯ These authors contributed equally to this work. 1
0 Institute for Preventive Medicine and Public Health, Hanoi Medical University , Hanoi , Vietnam , 2 Johns Hopkins Bloomberg School of Public Health , Baltimore , Maryland, United States of America, 3 School of Medicine and Pharmacy, Vietnam National University , Hanoi , Vietnam , 4 Institute for Global Health Innovations, Duy Tan University , Da Nang , Vietnam
1 Editor: Donn J. Colby, Thai Red Cross AIDS Research Centre , THAILAND
Methadone maintenance treatment (MMT) services may reduce the risk of HIV transmission if patients completely adhere to the treatment. Identifying adherence patterns and potential related factors is vital for the sustainability of MMT program in Vietnam. This study examined social and structural factors associated with adherence to MMT among patients in different service delivery models. A total of 510 patients at three MMT clinics in Hanoi were interviewed. Measures of selfreported adherence included the number of missed doses in the past 7 days and the level of adherence in the past 30 days using a visual analog scale (VAS) scoring from 0 (non-adherence) to 100 (perfect adherence). Multivariate regressions were employed to identify factors associated with non-adherence to MMT.
Data Availability Statement: Data are owned by
the Vietnam Authority of HIV/AIDS Control and
protected by the Law of HIV/AIDS prevention and
control; therefore, the dataset cannot be shared
publicly. Requests for data can be sent to Dr. Phan
Thi Thu Huong, Vice Director of the Vietnam
Authority of HIV/AIDS Control
(). Other researchers
can access these data in the same manner as the
authors. The authors did not have any special
access privileges that others would not have.
Materials and methods
A total of 17.7% of participants reported incomplete MMT adherence in the last 30 days and
8.3% reported missing a dose in the last seven days, respectively. Living with HIV/AIDS,
poor self-care and usual activities, and disclosure of health issues to spouses or intimate
partners were associated with non-adherence. Those patients with pain or depression were
more likely to report better adherence. Disclosing health status to spouse/partner increased
the risk of incomplete adherence, while disclosing to friends reduced the number of missed
dose in the last seven days. Patients attending clinics with comprehensive services had a
lower VAS score of adherence compared to those enrolling in clinics with only MMT and
general health care.
Funding: The authors received no specific funding
for this work.
Competing interests: The authors have declared
that no competing interests exist.
Sustaining the compliance of patients to MMT is principal in the rapid expansion of this
service in Vietnam. It is necessary to address the complexity of health care demands of drug
users, their difficulties to be rehabilitated into workforce and society, and the stigmatization
to maximize the outcomes of MMT program.
Globally, methadone maintenance treatment (MMT) is recognized as an essential and
costeffective substitution therapy for opioid dependent individuals [1±3]. MMT is efficacious in
reducing drug use-related consequences and improving health and socioeconomic status of
drug users [1,2,4±6]. In injection-driven HIV epidemics, the expansion of MMT services not
only reduced the risk of HIV transmission, but also supported patients' access, utilization and
outcomes of other HIV-related services [7±9]. Literature has shown that MMT clinics could be
strategic sites in providing directly administered antiretroviral therapy models for
HIV-positive drug users [
]. Given its benefits, the expansion of MMT is a vital component of global
HIV/AIDS prevention strategies [
MMT is a long-term and slow-onset substitution therapy, which needs complete
medication adherence to achieve optimal outcomes [
]. The current practice in Vietnam requires
patients to visit clinic daily and take medication under strict supervisions of health staff. This
practice is also applied in other South Asia countries such as Bangladesh, India, Nepal and
Maldives , or in some European countries and Canada [
]. In China, in addition to the
traditional delivery model, the Government implements a mobile service model to provide
methadone for patients in rural and remote areas .
Ensuring patients' adherence has increasingly challenged HIV programs in many settings.
In some countries such as China, Vietnam and Malaysia, where concurrent epidemics of HIV
and substance abuse exists, it has been well documented that patients' adherence to MMT was
not optimal and the retention rate was just 40% over 3 years [18±20]. In developed settings, a
growing body of evidence has shown the poor adherence among patients receiving MMT. In
the United States, studies have found 17% of patients did not adhere the therapy, and in
Canada this number has been reported to be 16% [
]. Other observations in the United
Kingdom, France, and Australia indicated high rates of non-adherence at 42.0%; 65.2%, and 33%,
Several studies have documented individual and biological factors which were associated
with non-adherence to MMT services. They included lower socioeconomic status, lack of
social support, discrimination and insufficient methadone doses [26±30]. Meanwhile, some
structural barriers were also recognized to predict non-adherence to MMT including patients'
satisfaction with healthcare services, poverty, jobs and housing, in both developed and
developing countries [19,23,24,28,31±33]. However, these factors varied across study settings, and
very few ones have focused on the provision of MMT in relation to other HIV services.
Vietnam is one among those countries with a strong political will to implement MMT
program and halt the spread of HIV epidemics in drug-using populations. Since its first
introduction in 2008, 251 MMT clinics have been established and providing treatment for over 46,000
]. The Vietnam's MMT program has been proved to effectively contribute to the
control and prevention of HIV/AIDS [35±37]. However, poor medication adherence poses a
great challenge to health managers in the rapid expansion of MMT services in Vietnam. A
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longitudinal study in Hai Phong and Ho Chi Minh cities in Vietnam showed that after 24
months of treatment, 41.4% patients reported missing dose for 1±2 days [
]. Another study
conducted in a mountainous area indicated that 65.6% patients had sub-optimal adherence to
Hanoi is a capital of Vietnam, where is an HIV/AIDS epicenter with more than 18,000
people living with HIV [
] and about 5,000 patients participating in the MMT program [
Evidence about the adherence pattern among MMT patients in this city would contribute
substantially to the development of strategies to maximize the outcomes of MMT program in
Vietnam. Therefore, this study assessed patients' adherence to MMT services and examined its
social and structural determinants.
Material and methods
Study design and setting
We conducted a facility-based cross-sectional survey in Hanoi from April to August 2013. We
selected clinics based on following criteria: 1) Currently providing the MMT service, and 2)
Having at least 100 patients taking MMT during data collection. Among six eligible facilities,
we randomly chose three clinics including: Tu Liem district health center (DHC), Long Bien
DHC and Ha Dong polyclinic. The features of these clinics are described in Table 1.
Sample size and sampling method
We used a convenience sampling technique to recruit patients. All patients at these selected
clinics were offered invitations to participate in the study if they were receiving MMT at the
selected clinics, 18 years old or above, and attended clinics during the study period. Finally,
data from 510 patients were used for analysis (response rate 80±90% across clinics).
Measures and instruments
Data were obtained via face-to-face interviews using a structured questionnaire. A private
room was employed for the interviews to assure the confidentiality of patients. Interviewers
were students in Master of Public Health program at Hanoi Medical University, under the
supervision of experts in the field of substance abuse. Each interview was performed in 15±20
The main outcome of this study was the self-reported medication adherence. Patients were
asked to report their adherence in the last seven days by using the question: ªHow many days
did you miss dose in the last seven days?º. Optimal adherence was detected when patients did
not miss any dose. Moreover, a 100-point visual analog scale (VAS) was also employed to
detect patients' adherence in the last 30 days, with a score range from 0 ªcomplete
non-adherenceº to 100 ªperfect adherenceº. These approaches had been successfully applied in a previous
]. While the number of missed doses in the past 7 days is an indicator to describe
recent adherence, the VAS score is a general measure that reflects the overall adherence over a
District Health Centre
District Health Centre
Type of services
MMT+ HCT + ART + GH
MMT+ HCT + ART + GH
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MMT: Methadone maintenance treatment; HCT: HIV counseling and testing; ART: antiretroviral therapy; GH: General health care
period of treatment. These two indicators were supplementary to each other. We also asked
patients to report their reasons if they did not adhere the treatment.
In this study, based on previous literatures, we measured social and structural factors as
Socioeconomic status. We collected socio-demographic status of patients, including: age,
gender, education, marital status and employment status.
Social factors. Health status. We applied a well-validated tool namely EuroQolÐfive
dimensions±five levels (EQ-5D-5L), which evaluated five components: Mobility, Self-care,
Usual activities, Pain/Discomfort and Anxiety/Depression. Each domain had five response
levels from no problem to extreme problems. This instrument was used previously in the context
of Vietnam [5,38,40±49].
Stigmatization. We investigated the drug use-related stigma among patients by using the
instrument that was used and validated elsewhere [
]. We evaluated four aspects of stigma
including: (1) Blame/Judgement, (2) Shame, (3) Discrimination in several settings (work
place, health care services, family, and community), (4) Disclosure of addiction or health
status. The short description of this instrument can be found in our previous publications
]. In short, patients were asked to report whether they suffered any of these kinds of
stigma in the last 30 days.
Structural factors. Satisfaction. We also employed an instrument entitled the Satisfaction
with HIV/AIDS Treatment Interview Scale (SATIS), which was used and validated previously
in Vietnam to measure the satisfaction of patients to the HIV-related services such as ART and
]. Overall, the SATIS has ten items with a score range from 0 ªcomplete
dissatisfactionº to 10 ªcomplete satisfactionº. There are three sub-domains namely: ªServices quality
and convenienceº, ªCapacity health workers & responsivenessº and ªInter-professional careº.
The score of each sub-domain was calculated by averaging the score of all items in the
STATA software version 12.0 (Stata Corp. LP, College Station, United States of America) was
used to analyze data. A p-value <0.05 was used to detect statistical significance. T-test,
MannWhitney test, Chi-square test and Fisher's exact test were used to assess the differences of
variables between adherence and non-adherence groups. We utilized multivariate Logistic, Tobit
and Zero-inflated Poisson regressions to identify factors associated with MMT adherence
among patients. A step-wise forward selection strategy was used with a p-value of <0.2 as a
threshold of the log-likelihood ratio test to select variables.
All study materials were approved by the IRB of the Vietnam Authority of HIV/AIDS Control.
Data collection procedures were also approved by the directors of each of the three MMT
clinics included in the study. Written informed consent was obtained from all participants.
Among 510 patients, the mean age was 36.6 (SD = 7.7) years old. Most of them were male
(98.4%), attaining less than high school education (53.7%) and living with their
spouse/partners (70.0%). The majority of respondents were self-employed (52.7%) or unemployed
(26.6%). Compared with the incomplete adherence group, more respondents in the complete
adherence group had under high school education (56.2% vs 41.3%) (p = 0.03). We did not
find any differences in other socioeconomic and health status factors (Table 2).
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OR: Odds ratio;
a Reference group: Not have these health states or experience any stigmatizations
PLOS ONE | https://doi.org/10.1371/journal.pone.0190941
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disclosing health status to spouse/partner were more likely to incompletely adhere the
medication, while respondents having pain/discomfort were less likely to be incomplete adherers.
Although complete adherence to MMT is principal in ensuring drug abstinence, we have
found that over one sixth of the study sample reported incomplete adherence. This was driven
by the complexity of health care demands and the difficulties constraining drug users in the
reintegration into workforce and society.
The proportion of MMT non-adherence in this study (17.8%) was lower than observations
in other studies across diverse settings, such as in France (42,0%) [
]; the United Kingdom
]; Australia (33.0%) [
] and China (36.3% to 88.2%) [
]. We would
acknowledge the potential reason for this difference that we measured adherence using missed doses in
the past 7 days and overall VAS scores for the past 30 days; meanwhile, other researchers
assessed adherence over 1, 3 and 12 months. In addition, some patients may over-report the
level of adherence using VAS while ignoring doses they have missed if it was too few.
Comparing to the previous study in Vietnam, the proportion of 8.3% patients missed doses
in the past seven days in our observation is lower than that in a mountainous setting in
Vietnam (10%) [
]. Urban patients probably access more easily to MMT clinics than those with
geolocation barriers. Noticeably, in mountainous settings, the 3-month non-adherence rate
was 65.6% and increased over the course of MMT [
]. Therefore, the adherence monitoring
and the provision of support and counseling should be maintained to reassure the MMT
retention and complete adherence of the patients [
In this study, higher age was found to be associated with better treatment adherence, while
high education was related to the incomplete adherence. These results are similar to other
previous findings [
]. Besides, patients having problems in self-care had a higher chance to
be non-adherers. Noteworthy is that poor self-care might restrict the functional capacity of
patients and reduce the effort to visit the clinic for taking medicine [
]. Otherwise, patients
having pain/discomfort were more likely to adhere the medication, which was contrary to the
previous findings that having physical and psychological problems could decrease adherence
]. Notably, the main reason for not adherence was having busy work (57.1%). Since
most of the respondents were self-employed or worked for hire with daily wages, they have to
manage their time and commitment to their work as well as to go to the clinic for MMT
]. Poverty and job commitment have been described as major structural barriers for
adherence to healthcare services in many settings. In this study, we enrich the literature by
describing the concurrent impacts of job commitment and stigma to drug users. Having a job
is very necessary for the patients by improving their social and economical status, but their
physical healthcare was demanding the methadone medications daily. This is also an
explanation that those with better health status will go for work and poorly adhered to MMT, while
those with severer pain or depression issues were better adhering to the treatment.
Interestingly, we found that people who ever disclosed to their spouse/partner were more
likely to report incomplete adherence, while patients disclosing their status to their friends
were more likely to adhere the medication. Literatures emphasized the benefits of health status
disclosure to medication adherence in various patient groups such as having more social
support, less psychological distress and receiving timely coping strategies for their problems
]. However, these advantages rely on how the patients interact with their societies
]. If they had negative relationships, disclosure could lead to serious stigmatization and
rejection, and eventually, negatively influence medication adherence . Besides, only a few
patients reported feeling stigma in their workplaces, families, health services or communities.
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Perhaps, patients who disclosed their health status to the spouse/partner could release the
pressure on themselves regarding treatment, and tend to allow them skipping several doses without
any concerns about clinical consequences [
]. It could also be the case that their spouse/
partner was also a drug abuser that make it more difficult for the patient to completely adhere
When we investigated structural barriers such as MMT delivery models and the satisfaction
of patients to the adherence, we only found that patients attending clinics delivering
comprehensive services (MMT+ART+HCT+GH) had a lower VAS score of adherence compared to
those enrolling in clinics with only MMT and GH. However, rather than the provision of
services, this could be explained by potential interactions of ART and methadone, which was
found to be related with lower methadone serum concentrations and adverse effects such as
depression, insomnia and myalgias, facilitating the non-adherence among HIV(+) patients (as
shown in multivariate regression) [64±66].
The findings of this study suggest some implications. First, the participation of patients'
spouse or partners has a central role in reminding patients to adhere the medication. Second,
MMT clinics should be integrated with the general health care service in order to understand
the needs of health care among patients and resolve timely during their treatment. Moreover,
the provision of MMT program should be connected among clinics, which can help patients
to access MMT in the nearest places where they feel convenient to take medication. Finally,
developing early warning system involving both clinical and self-reported data to inform the
adherence of patients might be helpful to improve the treatment outcome of MMT program.
There are several limitations in this study that should be recognized. First, using the
crosssectional design did not permit us to understand the causal associations between adherence
and its determinants. Second, we only collected self-reported information, which might lead to
recall bias [
]. Finally, our small sample size recruited by the convenience sampling method
might limit the generalizability of this study to other MMT populations. Moreover, medication
adherence is complicated to measure by self-reported data alone; therefore, a larger survey
with more clinical, biomedical and behavioral information should be warranted in the future
to provide the comprehensive view of this issue.
In conclusion, our study showed a low rate of non-adherence among MMT patients in a
Vietnam metropolitan compared to other settings. Having stable jobs, improve the ability to
engage in self-care, promote the role of spouse/partner and friends of patients, integrating
MMT clinics with general health care and connecting clinics in the provision of MMT
program could be potential solutions to enhance the adherence of MMT patients.
The authors would like to acknowledge supports of the Vietnam Authority of HIV/AIDS
Control for the implementation of the study.
Conceptualization: Bach Xuan Tran, Long Hoang Nguyen, Carl A. Latkin.
Data curation: Bach Xuan Tran, Long Hoang Nguyen, Tung Thanh Tran, Carl A. Latkin.
Formal analysis: Bach Xuan Tran.
Methodology: Bach Xuan Tran, Long Hoang Nguyen, Tung Thanh Tran, Carl A. Latkin.
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Project administration: Bach Xuan Tran, Carl A. Latkin.
Supervision: Bach Xuan Tran, Long Hoang Nguyen.
Visualization: Bach Xuan Tran.
Writing ± original draft: Bach Xuan Tran, Long Hoang Nguyen, Tung Thanh Tran, Carl A.
Writing ± review & editing: Bach Xuan Tran, Long Hoang Nguyen, Tung Thanh Tran, Carl
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inequalities. BMC Health Services Research 17: 480. https://doi.org/10.1186/s12913-017-2405-y
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