title: Relative effects of antiretroviral therapy and harm reduction initiatives on HIV incidence in British Columbia, Canada, 1996-2013: a modelling study.
abstract: Antiretroviral therapy (ART) and harm reduction services have been cited as key contributors to control of HIV epidemics; however, the specific contribution of ART has been questioned due to uncertainty of its true efficacy on HIV transmission through needle sharing. We aimed to isolate the independent effects of harm reduction services (opioid agonist treatment uptake and needle distribution volumes) and ART on HIV transmission via needle sharing in British Columbia, Canada, from 1996 to 2013.
  
  
  
  We used comprehensive linked individual health administrative and registry data for the population of diagnosed people living with HIV in British Columbia to populate a dynamic, compartmental transmission model to simulate the HIV/AIDS epidemic in British Columbia from 1996 to 2013. We estimated HIV incidence, mortality, and quality-adjusted life-years (QALYs). We also 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, and we investigated structural and parameter uncertainty.
  
  
  
  We estimate that 3204 (upper bound-lower bound 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% (upper bound-lower bound 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. As a result of high distribution volumes, needle distribution predominantly accounted for incidence reductions attributable to harm reduction but opioid agonist treatment provided substantially greater QALY gains.
  
  
  
  If the true efficacy of ART in preventing HIV transmission through needle sharing is closer to its efficacy in sexual transmission, ART's effect on incident cases averted could be greater than that of harm reduction. Nonetheless, harm reduction services had a vital role in reducing HIV incidence in British Columbia, and should be viewed as essential and cost-effective tools in combination implementation strategies to reduce the public health and economic burden of HIV/AIDS.
  
  
  
  BC Ministry of Health; National Institutes of Health (R01DA041747); Genome Canada (142HIV).
authors.affiliation: BC Centre for Excellence in HIV/AIDS, St Paul's Hospital, Vancouver, BC, Canada; Faculty of Health Sciences, Simon Fraser University, Burnaby, BC, Canada. Electronic address: bnosyk@cfenet.ubc.ca.
authors.forename: Bohdan
authors.initials: B
authors.lastname: Nosyk
authors.affiliation: BC Centre for Excellence in HIV/AIDS, St Paul's Hospital, Vancouver, BC, Canada; Faculty of Health Sciences, Simon Fraser University, Burnaby, BC, Canada.
authors.forename: Xiao
authors.initials: X
authors.lastname: Zang
authors.affiliation: BC Centre for Excellence in HIV/AIDS, St Paul's Hospital, Vancouver, BC, Canada.
authors.forename: Jeong E
authors.initials: JE
authors.lastname: Min
authors.affiliation: BC Centre for Excellence in HIV/AIDS, St Paul's Hospital, Vancouver, BC, Canada.
authors.forename: Emanuel
authors.initials: E
authors.lastname: Krebs
authors.affiliation: BC Centre for Excellence in HIV/AIDS, St Paul's Hospital, Vancouver, BC, Canada; Division of AIDS, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Viviane D
authors.initials: VD
authors.lastname: Lima
authors.affiliation: BC Centre for Excellence in HIV/AIDS, St Paul's Hospital, Vancouver, BC, Canada; Division of AIDS, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada.
authors.forename: M-J
authors.initials: MJ
authors.lastname: Milloy
authors.affiliation: BC Centre for Excellence in HIV/AIDS, St Paul's Hospital, Vancouver, BC, Canada; School of Population and Public Health, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Jean
authors.initials: J
authors.lastname: Shoveller
authors.affiliation: BC Centre for Excellence in HIV/AIDS, St Paul's Hospital, Vancouver, BC, Canada; Division of AIDS, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Rolando
authors.initials: R
authors.lastname: Barrios
authors.affiliation: BC Centre for Excellence in HIV/AIDS, St Paul's Hospital, Vancouver, BC, Canada; Division of AIDS, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada.
authors.forename: P Richard
authors.initials: PR
authors.lastname: Harrigan
authors.affiliation: BC Centre for Excellence in HIV/AIDS, St Paul's Hospital, Vancouver, BC, Canada; Division of AIDS, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Thomas
authors.initials: T
authors.lastname: Kerr
authors.affiliation: BC Centre for Excellence in HIV/AIDS, St Paul's Hospital, Vancouver, BC, Canada; Division of AIDS, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Evan
authors.initials: E
authors.lastname: Wood
authors.affiliation: BC Centre for Excellence in HIV/AIDS, St Paul's Hospital, Vancouver, BC, Canada; Division of AIDS, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Julio S G
authors.initials: JSG
authors.lastname: Montaner
mesh_terms: D000293:Adolescent; D000328:Adult; D044966:Anti-Retroviral Agents / Q000627:therapeutic use*; D023241:Antiretroviral Therapy, Highly Active / Q000379:methods*; D001955:British Columbia / Q000453:epidemiology; D018562:Disease Transmission, Infectious / Q000517:prevention & control*; D005260:Female; D015658:HIV Infections / Q000188:drug therapy* / Q000453:epidemiology / Q000635:transmission*; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D016485:Needle Sharing / Q000009:adverse effects*; D018570:Risk Assessment; D015819:Substance Abuse, Intravenous / Q000150:complications*; D016019:Survival Analysis; D055815:Young Adult
chemical_list: D044966:Anti-Retroviral Agents