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Title
Engagement in methadone maintenance therapy associated with less time with plasma HIV-1 RNA viral load above 1500 copies/mL among a cohort of HIV-positive people who use drugs in Vancouver, Canada
Presenter
Brittany Barker
Authors
B. Barker1,2, C. Fairgrieve1, K. Ahamad1,3,4, T. Kerr1,5, J. Shoveller6, J. Montaner5,7, E. Wood1,5, M.-J. Milloy1,5
Institutions
1BC Centre on Substance Use, Vancouver, Canada, 2University of British Columbia, Interdisciplinary Studies Graduate Program, Vancouver, Canada, 3Providence Health Care, Department of Family and Community Medicine, Vancouver, Canada, 4University of British Columbia, Department of Family Medicine, Vancouver, Canada, 5University of British Columbia, Department of Medicine, Division of AIDS, Vancouver, Canada, 6University of British Columbia, School of Population and Public Health, Vancouver, Canada, 7BC Centre for Excellence in HIV/AIDS, Vancouver, Canada

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.


Table 1. Generalized estimating equation analyses of factors associated with person-time exceeding an HIV-1 RNA viral load above 1500 copies/mL plasma
[Table 1. Generalized estimating equation analyses of factors associated with person-time exceeding an HIV-1 RNA viral load above 1500 copies/mL plasma]