People on methadone maintenance treatment spent less time with a detectable viral load above 1,500 copies/ml, potentially reducing the risk of HIV transmission, a study presented by researchers at the BC Centre on Substance Use, Vancouver, Canada, University of British Columbia, Providence Health Care, Department of Family and Community Medicine, Vancouver and the BC Centre for Excellence in HIV/AIDS, at last month’s 22nd International AIDS Conference (AIDS 2018) has found.
Methadone is an opioid substitution treatment prescribed to minimise the harms associated with the use of heroin or other opioids. Methadone maintenance treatment also promotes improved adherence to antiretroviral treatment and retention in care in people living with HIV who use drugs. Buprenorphine, an alternative to methadone, is widely prescribed in France and North America.
Although the use of methadone maintenance treatment is known to reduce the incidence of HIV in people who use drugs by reducing the frequency of injecting, it is not known whether, by influencing adherence and care-seeking behaviour, methadone maintenance treatment has an impact on virological control.
To answer this question, researchers from the British Columbia Centre on Substance Use looked at the relationship between the time spent accessing methadone maintenance treatment through low-threshold facilities – those that make it as easy as possible for drug users to obtain methadone – and the time spent with a viral load above 1500 copies/ml.
Having a viral load above 1500 copies/ml is associated with an increased risk of HIV transmission to sexual partners. The viral load threshold at which the risk of HIV transmission through shared injecting equipment increases is not known, so the level of 1500 copies/ml used in this study is an assumption.
The study population was drawn from a British Columbia cohort, the AIDS Care Cohort to Evaluate Access to Survival Services (ACCESS), of people living with HIV who use illicit drugs. All participants in the cohort study taking antiretroviral therapy were eligible for inclusion in this analysis if they had at least two viral load measurements. Viral load was routinely sampled every six months. These measurements were linked to antiretroviral prescription dispensing records and to self-reports of methadone uptake.
The study population comprised 867 people who used drugs in care between 2005 and 2017. The study accumulated 4,532 person-years of follow-up; during this period 60% of participants received methadone maintenance treatment for at least some of the time – 63% of the study population was male.
During the study period, 67% of the sample had at least one period of viral load over 1500 copies/ml and on average, spent 19% of the observation time with a viral load above 1500 copies/ml. Engagement in methadone maintenance therapy was independently associated with a reduced risk of time spent with a viral load above 1500 copies/ml: people who received methadone were 30% less likely to have a viral load above 1500 copies/ml at any point during the study period (adjusted hazard 0.70, 95% CI 0.60-0.81, p < 0.001).
Presenting the findings, Brittany Barker, a PhD candidate at the University of British Columbia, said that methadone maintenance treatment is a key intervention for reducing onward HIV transmission in the community and that the group’s findings support the scale-up of evidence-based addiction care, including the reduction of barriers to methadone or buprenorphine prescribing by non-specialist physicians.
Background: It is well established that elevated plasma HIV-1 RNA viral load (VL) drives the risk of onward viral transmission. Despite being a key population living with HIV, people who inject drugs continue to experience individual, social and structural barriers in accessing and being retained in HIV treatment and care. In the present study, we sought to longitudinally examine the relationship between engagement in a low-threshold methadone maintenance therapy (MMT) program and amount of person-time with heightened HIV transmission risk (i.e., VL >1500 copies/mL plasma) among HIV-positive people who use drugs (PWUD).
Methods: Data were derived from the AIDS Care Cohort to evaluate Exposure to Survival Services (ACCESS), a community-recruited prospective cohort of HIV-positive PWUD in Vancouver, Canada. Longitudinal cohort data was confidentially linked to comprehensive HIV clinical monitoring records in a setting of universal no-cost HIV treatment and care. We used generalized estimating equation analyses to assess the impact of engagement in low-barrier MMT on the number of days with an HIV-1 RNA VL above 1500 c/mL in the previous 180 days.
Results: Between 5 December 2005 and 29 November 2017, 867 HIV-seropositive antiretroviral therapy-exposed PWUD were recruited and contributed 4531 person-years of observation time. Among these, 522 (60.2%) were engaged in MMT at least once during follow-up. In a multivariable model, periods of MMT were independently associated with fewer days with a VL above 1500 c/mL (Adjusted Rate Ratio=0.70, 95% Confidence Interval: 0.60-0.81), after controlling for demographics, drug use patterns, and CD4 count.
Conclusions: We observed that engagement in MMT was associated with significantly less person-time with a VL above 1500 copies/mL among a large and long running cohort of PWUD. These findings suggest that low-threshold MMT is an effective intervention in lowering the risk of onward viral transmission among this key population. Further, these findings demonstrate the important role of evidence-based addiction treatment in optimizing individual and community-level impacts of antiretroviral therapy among HIV positive patients with comorbid opioid dependence. Efforts to address barriers to the use and availability of MMT will likely improve HIV outcomes and reduce new infections among this population and should therefore be prioritized.
B Barker, C Fairgrieve, K Ahamad, T Kerr, J Shoveller, J Montaner, E Wood, MJ Milloy