Meeting the challenges of opioid dependence in China: experience of opioid agonist treatment

Metabolic and functional substrates of impulsive decision-making in individuals with heroin addiction after prolonged methadone maintenance treatment

Elevated impulsivity has been frequently reported in individuals with opioid addiction receiving methadone maintenance therapy (MMT), but the underlying neural mechanisms and cognitive subprocesses are not fully understood. We acquired functional magnetic resonance imaging (fMRI) data from 37 subjects with heroin addiction receiving long-term MMT and 33 healthy controls who performed a probabilistic reversal learning task, and measured their resting-state brain glucose using fluorine-18-fluorodeoxyglucose positron emission tomography (18F-FDG PET). Subjects receiving MMT exhibited significantly elevated self-reported impulsivity, and computational modeling revealed a marked impulsive decision bias manifested as switching more frequently without available evidence. Moreover, this impulsive decision bias was associated with the dose and duration of methadone use, irrelevant to the duration of heroin use. During the task, the switch-related hypoactivation in the left rostral middle frontal gyrus was correlated with the impulsive decision bias while the function of reward sensitivity was intact in subjects receiving MMT. Using prior brain-wide receptor density data, we found that the highest variance of regional metabolic abnormalities was explained by the spatial distribution of μ-opioid receptors among 10 types of neurotransmitter receptors. Heightened impulsivity in individuals receiving prolonged MMT is manifested as atypical choice bias and noise in decision-making processes, which is further driven by deficits in top-down cognitive control, other than reward sensitivity. Our findings uncover multifaceted mechanisms underlying elevated impulsivity in subjects receiving MMT, which might provide insights for developing complementary therapies to improve retention during MMT.

Regaining control over opioid use? The potential application of auricular transcutaneous vagus nerve stimulation to improve opioid treatment in China

Opioid use disorder (OUD) is a critical problem in China and is accompanied by depression and deficits in cognitive control. In China, the most successful intervention for OUD is the community drug rehabilitation where methadone maintenance treatment (MMT) plays a key role. Even though methadone for the treatment of OUD can be helpful, it can cause severe somatic side-effects, which limit its effectivity. Even worse, it can have detrimental effects on cognitive control, which is crucial to regain control over drug intake. Here, we consider the potential use of auricular transcutaneous vagus nerve stimulation (atVNS) as an addition to MMT for opioid withdrawal treatment. Compared to other non-invasive brain stimulation methods, atVNS also targets the locus coeruleus (LC) important for noradrenaline (NA) synthesis. NA is an essential neurotransmitter impacted in opioid withdrawal and also critically involved in cognitive control processes. Its ADD-ON to MMT might be a useful mean to improve mood and enhance cognitive control processes impacted in OUD. We discuss the translational advantages of atVNS in China such as the cultural acceptance of the modality of treatment similar to electroacupuncture. Additionally, the wearability of the ear electrode and at-home self-administration without intense medical supervision makes of atVNS a useful tool to enhance clinical and cognitive outcomes especially in everyday life situation. We discuss how atVNS can be integrated in tele-medical health approaches allowing that innovative treatments can widely be disseminated and continued even in situations of restricted medical access.

Developing non-opioid therapeutics to alleviate pain among persons with opioid use disorder: a review of the human evidence

The opioid crisis remains a major public health concern, causing significant morbidity and mortality worldwide. Pain is frequently observed among individuals with opioid use disorder (OUD), and the current opioid agonist therapies (OAT) have limited efficacy in addressing the pain needs of this population. We reviewed the most promising non-opioid analgesic therapies for opioid-dependent individuals synthesising data from randomised controlled trials in the Medline database from December 2022 to March 2023. Ketamine, gabapentin, serotoninergic antidepressants, and GABAergic drugs were found to be the most extensively studied non-opioid analgesics with positive results. Additionally, we explored the potential of cannabinoids, glial activation inhibitors, psychedelics, cholecystokinin antagonists, alpha-2 adrenergic agonists, and cholinergic drugs. Methodological improvements are required to advance the development of novel analgesic strategies and establish their safety profile for opioid-dependent populations. We highlight the need for greater integration of experimental pain methods and abuse liability assessments, more granular assessments of prior opioid exposure, greater uniformity of pain types within study samples, and a particular focus on individuals with OUD receiving OAT. Finally, future research should investigate pharmacokinetic interactions between OAT and various non-opioid analgesics and perform reverse translation basic experiments, particularly with methadone and buprenorphine, which remain the standard OUD treatment.

The risk assessment of relapse among newly enrolled participants in methadone maintenance treatment: A group-LASSO based Bayesian network study

Background

Relapse is a great barrier to improving the effectiveness of methadone maintenance treatment (MMT). Participants with different treatment durations could vary in their compliance with MMT, which may lead to different levels of relapse risk. This study aims to identify the risk factors for relapse and assess the relapse risk of MMT participants of different treatment durations.

Method

This retrospective study used data collected from seven MMT clinics in Guangdong Province, China, from January 2010 to April 2017. Newly enrolled participants who received 6 (n = 903) and 12 (n = 710) months of consecutive treatment with complete data were included. We selected significant risk factors for relapse through the group lasso regression and then incorporated them into Bayesian networks to reveal relationships between factors and predict the relapse risk.

Results

The results showed that participants who received 6-month treatment had a lower relapse rate (32.0%) than those of 12-month treatment (39.0%, P < 0.05). Factors including personal living status and daily methadone dose were only influential to those who received the 6-month treatment. However, age, age at the initial drug use, HIV infection status, sexual behaviors, and continuous treatment days were common factors of both durations. The highest relapse risk for those after the 6-month treatment was inferred as 66.7% while that of the 12-month treatment was 83.3%. Farmers and those who have high accessibility to MMT services may require additional attention.

Conclusion

It is necessary to implement targeted interventions and education based on the treatment durations of participants to decrease the relapse rate. Meanwhile, those about HIV/sexually transmitted infection prevention and anti-narcotics should be held in the whole process.

Exploration of dose tapering strategies for methadone maintenance treatment based on relapse risks: A subpopulation treatment effect pattern plot (STEPP) analysis

BACKGROUND

Half of methadone maintenance treatment (MMT) participants experience a tapering phase, however, the guidelines vary from country to country and lack individualized strategies based on relapse risk. A detailed and individualized tapering strategy is needed in China. This study aims to explore dose tapering strategies for Chinese individuals with different relapse risks.

METHODS

A retrospective study was conducted from 2006 to 2017 at nine MMT clinics in Guangdong, China, involving 549 participants. The end point was the first relapse within 12 months of the start of tapering. Relapse risks before tapering for each participant were determined from a Cox model.

RESULTS

Out of 549 participants, 173 (31.5 %) relapsed within 12 months after tapering. Findings indicated that a taper dose of less than 5 mg/week is better than other taper doses. Subpopulation treatment effect pattern plot (STEPP) methodology revealed different tapering strategies benefit participants according to relapse risk before tapering. Overall, findings indicated that a less than 5 mg/week reduction in MMT dose is better than reductions of other amounts. For participants with a low relapse risk before tapering, a reduction of less than 2.5 mg/week in MMT dose is better than a 2.5-5 mg/week reduction.

CONCLUSIONS

A taper dose of less than 5 mg/week appears to be the best dose tapering strategy for Chinese participants. Furthermore, for participants with a low relapse risk, a more gradual taper dose (less than 2.5 mg/week) works better than 2.5-5 mg/week. This benefit was not seen in participants with a high relapse risk before tapering.

Time trends and associated factors of global burden due to drug use disorders in 204 countries and territories, 1990-2019

BACKGROUND

Drug use disorders (DUDs) have been a public health crisis which strongly impacted community health and socio-economic development. However, there are few studies based on the latest global data to show changes in the disease burden due to DUDs, specifically investigating associations between the country-level socio-economic factors and the burden of DUDs.

METHODS

Data of DUDs were extracted from the Global Burden of Disease Study 2019 database to explore the trends of the disease burden due to DUDs from 1990 to 2019. Univariate linear regression and stepwise multiple linear regression analysis were performed to analyze the correlations between burden due to DUDs and country-level socio-economic factors.

RESULTS

Globally, the number of disability-adjusted life-years (DALYs) caused by DUDs approximately increased by 2.6% yearly from 1990 to 2019, though the age-standardized DALY rate has not changed significantly in the past 30 years. The age-standardized DALY rate of opioid use disorders showed an upward trend during the past 30 years and was highest among 5 types of DUDs in 2019. Inequality-adjusted human development index (β = 15.9, 95% confidence interval [CI]: 12.9-18.9, P < 0.001) was identified as the key risk factor associated with square-root transformed age-standardized DALY rate of DUDs.

CONCLUSIONS

Global burden due to DUDs has increased significantly over the past 30 years. More effective targeted public health policies should be formulated to manage the public health challenge of DUDs, especially in developed countries and territories.

Dose Tapering Strategy for Heroin Abstinence among Methadone Maintenance Treatment Participants: Evidence from A Retrospective Study in Guangdong, China

Around half of methadone maintenance treatment (MMT) participants choose the tapering phase, however, the guidelines on tapering differ between countries and only include the tapering rate. Physicians need more evidence to guide clinical practice. We aimed to explore a specific tapering strategy to improve heroin abstinence among MMT participants. We conducted a retrospective study from 2006 to 2017 at nine MMT clinics in Guangdong, China, involving 853 participants with 961 treatment episodes. We performed two-level hierarchical logistic regression models to identify tapering phase characteristics associated with heroin abstinence. Among all treatment episodes, 419 (43.6%) were heroin abstinent. Participants who started tapering after 52 weeks, had a taper start dose of less than 60 mg and a taper ratio of less than 5%/week, while a dose reduction in 75%-89% of the tapering weeks provided the highest odds of heroin abstinence. This study highlights the need for a more gradual taper than current guidelines recommend and strongly suggests the inclusion of other tapering phase characteristics. Those who start the tapering phase later, have a lower dose of methadone, with a more gradual rate of taper, and a dose reduction in 75%-89% of the tapering phase increased the odds of heroin abstinence.

Factors Associated with Compliance among Methadone Maintenance Treatment Transfers: Evidence from Audit Records at Clinics in Guangdong, China

Methadone maintenance treatment (MMT) requires patients to intake their daily dose in person at their clinic. Therefore, transfer services are vital for patients who need temporary leave from their primary MMT clinic. However, studies have shown that transfer patients might delay return after temporary leave, leading to missed doses and putting them at risk of increased harm. In this study, we aimed to explore the transfer rates and factors associated with MMT patients who delayed return during a transfer period. In this retrospective analysis, we used audit records from the web-based management system from six MMT clinics in Guangdong, China. Multilevel logistic regression and multilevel Poisson regression analyses were used to examine the factors associated with patients who delayed return to their primary MMT clinic. A total of 459 people used the transfer system 2940 times between January 2006 and December 2016. Of those, patients delayed return to their primary MMT clinic 1199 times (40.78%). Patients who transferred regularly had poor compliance rates with MMT treatment. Those who once dropped out from and then re-enrolled in MMT were more likely to delay return. Most patients (82.71%) who used the transfer service for "work" were more likely to prolong their delay length. The findings highlight that a more flexible transfer system would minimize inconvenience to the patients.