Relative effects of antiretroviral therapy and harm reduction initiatives on HIV incidence in British Columbia, Canada, 1996–2013: a modelling study

Abstract

Summary Background Antiretroviral therapy (ART) and harm reduction services have been cited as key contributors to the control of the HIV epidemic, however the specific contribution of the latter has been questioned due to uncertainty in the true efficacy of ART on HIV transmission through needle sharing. Using provincial data on OAT uptake and needle distribution volumes, we aimed to isolate the independent effects of harm reduction services and ART on HIV transmission via needle sharing in British Columbia, from 1996–2013. Methods Using comprehensive linked population-level data, we populated a dynamic, compartmental transmission model to simulate the HIV/AIDS epidemic in BC from 1996–2013. HIV incidence, mortality, and quality-adjusted life years (QALYs) were estimated. We estimated scenarios designed to isolate the independent effects of harm reduction services and ART (assuming 50% (10%–90%) efficacy) in reducing HIV incidence through needle sharing. Structural and parameter uncertainty was investigated. Findings We estimated that 3204 (2402–4589) incident HIV cases were averted between 1996 and 2013 as a result of the combined effect of the expansion of harm reduction services and ART coverage on HIV transmission via needle sharing. In a hypothetical scenario assuming ART had zero effect on transmission through needle sharing, we estimated harm reduction services alone would have accounted for 77% (62%–95%) of averted HIV incidence. In a separate hypothetical scenario where harm reduction services remained at 1996 levels, we estimated ART alone would have accounted for 44% (10%–67%) of averted HIV incidence. Due to high distribution volumes, needle distribution predominantly accounted for incidence reductions attributable to harm reduction, however OAT provided substantially greater QALY gains. Interpretation If the true efficacy of ART in preventing HIV transmission through needle sharing is closer to its efficacy in sexual transmission, ART’s impact on incident cases averted may be greater than that of harm reduction. Nonetheless, harm reduction services played a vital role in reducing HIV incidence in BC, and should be viewed as critical and cost-effective tools in combination implementation strategies to reduce the public health and economic burden of HIV/AIDS.

A historical review of HIV prevention and care initiatives in British Columbia, Canada: 1996‐2015

“…Second, BC has adopted progressive policies towards harm reduction, which have facilitated wide distribution of harm reduction supplies and otherwise increased opioid agonist treatment access to individuals with opioid dependence ( Figure 3). Expansion of OAT and needle distribution since 1996 played a vital role in preventing HIV transmission among PWID, and declines in HIV among PWID has been credited as the primary driver behind consistent declines in BC's HIV incidence [10].…”

“…These changes led to considerable growth in the number of clients accessing opioid agonist treatment each year with overall enrolment increasing from only 2,800 clients in 1996 to approximately 15,418 in 2014 ( Figure 3)[ 25]. Given opioid agonist treatment has been associated with decreased needle-sharing [38], decreased HIV mortality [39] and improved HAART adherence [40], expanded access to opioid agonist treatment likely played a critical role in the decline of BC's HIV epidemic [10,41].…”

“…Given accumulating evidence that HAART prevents HIV transmission [1,[5][6][7][8][9], a wide range of initiatives to expand HAART uptake likely contributed to declines in new cases [10]. The simultaneous expansion of harm reduction services, including syringe distribution, opioid agonist treatment, and supervised injection facilities had a profound impact on the epidemic by reducing HIV transmission through needle sharing [10]. Governmental, clinical, and community-based groups, including drug user organizations, have also undertaken prevention and care initiatives since the onset of HAART to facilitate access to HIV care and prevention [11,12].…”

Realizing Women Living with HIV’s Reproductive Rights in the Era of ART: The Negative Impact of Non-consensual HIV Disclosure on Pregnancy Decisions Amongst Women Living with HIV in a Canadian Setting

“…With the advent of antiretroviral therapy (ART), and resulting improvements in life expectancy(1, 2), health and quality of life(3), and prevention of sexual and vertical HIV transmission(4, 5), an increasing number of women living with HIV (WLWH) are considering their reproductive options(6, 7). Globally, there has been a steady increase in the proportion of WLWH desiring children(6, 8–12).…”

Initiating HCV treatment with direct acting agents in opioid agonist treatment: When to start for people co-infected with HIV?

“…At the same time, the province expanded access to ART through provincial coverage at no cost to patients (Nosyk, Min, Lima et al, 2015), and funded testing and public health interventions aimed at improving HIV care (Gustafson, Montaner, & Sibbald, 2012). The combination of OAT and ART expansions with increased access to harm reduction services resulted in decreases in HIV-related morbidity, mortality and transmission (Nosyk, Min, Lima et al, 2015; Nosyk et al, 2017). Furthermore, in this setting characterized by universal healthcare and widespread access to both office-based OAT and ART, OAT among PWID was shown to substantially increase the odds of ART adherence (Nosyk, Min, Colley et al, 2015) and to independently protect against causes of death (Nosyk, Min, Evans et al, 2015).…”