title: Cost Effectiveness of Potential ART Adherence Monitoring Interventions in Sub-Saharan Africa.
abstract: BACKGROUND
  Interventions based around objective measurement of adherence to antiretroviral drugs for HIV have potential to improve adherence and to enable differentiation of care such that clinical visits are reduced in those with high adherence. It would be useful to understand the approximate upper limit of cost that could be considered for such interventions of a given effectiveness in order to be cost effective. Such information can guide whether to implement an intervention in the light of a trial showing a certain effectiveness and cost.
  
  
  METHODS
  An individual-based model, calibrated to Zimbabwe, which incorporates effects of adherence and resistance to antiretroviral therapy, was used to model the potential impact of adherence monitoring-based interventions on viral suppression, death rates, disability adjusted life years and costs. Potential component effects of the intervention were: enhanced average adherence when on ART, reduced risk of ART discontinuation, and reduced risk of resistance acquisition. We considered a situation in which viral load monitoring is not available and one in which it is. In the former case, it was assumed that care would be differentiated based on the adherence level, with fewer clinic visits in those demonstrated to have high adherence. In the latter case, care was assumed to be primarily differentiated according to viral load level. The maximum intervention cost required to be cost effective was calculated based on a cost effectiveness threshold of $500 per DALY averted.
  
  
  RESULTS
  In the absence of viral load monitoring, an adherence monitoring-based intervention which results in a durable 6% increase in the proportion of ART experienced people with viral load < 1000 cps/mL was cost effective if it cost up to $50 per person-year on ART, mainly driven by the cost savings of differentiation of care. In the presence of viral load monitoring availability, an intervention with a similar effect on viral load suppression was cost-effective when costing $23-$32 per year, depending on whether the adherence intervention is used to reduce the level of need for viral load measurement.
  
  
  CONCLUSIONS
  The cost thresholds identified suggest that there is clear scope for adherence monitoring-based interventions to provide net population health gain, with potential cost-effective use in situations where viral load monitoring is or is not available. Our results guide the implementation of future adherence monitoring interventions found in randomized trials to have health benefit.
authors.affiliation: Research Department of Infection & Population Health, UCL, London, United Kingdom.
authors.forename: Andrew N
authors.identifier: http://orcid.org/0000-0003-2384-4807
authors.initials: AN
authors.lastname: Phillips
authors.affiliation: Research Department of Infection & Population Health, UCL, London, United Kingdom.
authors.forename: Valentina
authors.initials: V
authors.lastname: Cambiano
authors.affiliation: Research Department of Infection & Population Health, UCL, London, United Kingdom.
authors.forename: Fumiyo
authors.initials: F
authors.lastname: Nakagawa
authors.affiliation: Research Department of Infection & Population Health, UCL, London, United Kingdom.
authors.forename: Loveleen
authors.initials: L
authors.lastname: Bansi-Matharu
authors.affiliation: Bill & Melinda Gates Foundation, Seattle, Washington, United States of America.
authors.forename: Papa Salif
authors.initials: PS
authors.lastname: Sow
authors.affiliation: Bill & Melinda Gates Foundation, Seattle, Washington, United States of America.
authors.forename: Peter
authors.initials: P
authors.lastname: Ehrenkranz
authors.affiliation: Institute for Clinical Trials and Methodology, UCL, London, United Kingdom.
authors.forename: Deborah
authors.initials: D
authors.lastname: Ford
authors.affiliation: Ministry of Health & Child Care, Harare, Zimbabwe.
authors.forename: Owen
authors.initials: O
authors.lastname: Mugurungi
authors.affiliation: Ministry of Health & Child Care, Harare, Zimbabwe.
authors.forename: Tsitsi
authors.initials: T
authors.lastname: Apollo
authors.affiliation: Ministry of Health & Child Care, Harare, Zimbabwe.
authors.forename: Joseph
authors.initials: J
authors.lastname: Murungu
authors.affiliation: Oregon Health Sciences University-Portland State University School of Public Health, Portland, Oregon, United States of America.
authors.forename: David R
authors.initials: DR
authors.lastname: Bangsberg
authors.affiliation: Centre for Health Economics, University of York, York, United Kingdom.
authors.forename: Paul
authors.initials: P
authors.lastname: Revill
mesh_terms: D017954:Africa South of the Sahara; D019380:Anti-HIV Agents / Q000627:therapeutic use*; D023241:Antiretroviral Therapy, Highly Active / Q000191:economics*; D018791:CD4 Lymphocyte Count; D003362:Cost-Benefit Analysis; D015658:HIV Infections / Q000188:drug therapy*; D006801:Humans; D019562:Viral Load / Q000187:drug effects
chemical_list: D019380:Anti-HIV Agents