title: Health benefits, costs, and cost-effectiveness of earlier eligibility for adult antiretroviral therapy and expanded treatment coverage: a combined analysis of 12 mathematical models.
abstract: BACKGROUND
  New WHO guidelines recommend initiation of antiretroviral therapy for HIV-positive adults with CD4 counts of 500 cells per μL or less, a higher threshold than was previously recommended. Country decision makers have to decide whether to further expand eligibility for antiretroviral therapy accordingly. We aimed to assess the potential health benefits, costs, and cost-effectiveness of various eligibility criteria for adult antiretroviral therapy and expanded treatment coverage.
  
  
  METHODS
  We used several independent mathematical models in four settings-South Africa (generalised epidemic, moderate antiretroviral therapy coverage), Zambia (generalised epidemic, high antiretroviral therapy coverage), India (concentrated epidemic, moderate antiretroviral therapy coverage), and Vietnam (concentrated epidemic, low antiretroviral therapy coverage)-to assess the potential health benefits, costs, and cost-effectiveness of various eligibility criteria for adult antiretroviral therapy under scenarios of existing and expanded treatment coverage, with results projected over 20 years. Analyses assessed the extension of eligibility to include individuals with CD4 counts of 500 cells per μL or less, or all HIV-positive adults, compared with the previous (2010) recommendation of initiation with CD4 counts of 350 cells per μL or less. We assessed costs from a health-system perspective, and calculated the incremental cost (in US$) per disability-adjusted life-year (DALY) averted to compare competing strategies. Strategies were regarded very cost effective if the cost per DALY averted was less than the country's 2012 per-head gross domestic product (GDP; South Africa: $8040; Zambia: $1425; India: $1489; Vietnam: $1407) and cost effective if the cost per DALY averted was less than three times the per-head GDP.
  
  
  RESULTS
  In South Africa, the cost per DALY averted of extending eligibility for antiretroviral therapy to adult patients with CD4 counts of 500 cells per μL or less ranged from $237 to $1691 per DALY averted compared with 2010 guidelines. In Zambia, expansion of eligibility to adults with a CD4 count threshold of 500 cells per μL ranged from improving health outcomes while reducing costs (ie, dominating the previous guidelines) to $749 per DALY averted. In both countries results were similar for expansion of eligibility to all HIV-positive adults, and when substantially expanded treatment coverage was assumed. Expansion of treatment coverage in the general population was also cost effective. In India, the cost for extending eligibility to all HIV-positive adults ranged from $131 to $241 per DALY averted, and in Vietnam extending eligibility to patients with CD4 counts of 500 cells per μL or less cost $290 per DALY averted. In concentrated epidemics, expanded access for key populations was also cost effective.
  
  
  CONCLUSIONS
  Our estimates suggest that earlier eligibility for antiretroviral therapy is very cost effective in low-income and middle-income settings, although these estimates should be revisited when more data become available. Scaling up antiretroviral therapy through earlier eligibility and expanded coverage should be considered alongside other high-priority health interventions competing for health budgets.
  
  
  BACKGROUND
  Bill & Melinda Gates Foundation, WHO.
authors.affiliation: Department of Infectious Disease Epidemiology, Imperial College London, London, UK.
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authors.affiliation: Research Department of Infection and Population Health, University College London, London, UK.
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authors.affiliation: Department of Global Health and Population, Harvard School of Public Health, Boston, MA, USA.
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authors.affiliation: MRC Centre for Outbreak Analysis and Modelling, Imperial College London, London, UK.
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authors.affiliation: Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands; Africa Centre for Health and Population Studies, University of KwaZulu-Natal, Mtubatuba, South Africa; Nijmegen International Center for Health System Analysis and Education (NICHE), Department of Primary and Community Care, Radboud University Nijmegen Medical Centre, Nijmegen, Netherlands.
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authors.affiliation: Department of Global Health and Population, Harvard School of Public Health, Boston, MA, USA.
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authors.affiliation: Department of Global Health and Population, Harvard School of Public Health, Boston, MA, USA; Africa Centre for Health and Population Studies, University of KwaZulu-Natal, Mtubatuba, South Africa.
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authors.affiliation: Department of Infectious Disease Epidemiology, Imperial College London, London, UK.
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authors.affiliation: Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, UK.
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authors.affiliation: Department of Infectious Disease Epidemiology, Imperial College London, London, UK.
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authors.affiliation: Social and Mathematical Epidemiology Group, London School of Hygiene & Tropical Medicine, London, UK.
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authors.affiliation: Department of HIV/AIDS, WHO, Geneva, Switzerland.
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mesh_terms: D000328:Adult; D023241:Antiretroviral Therapy, Highly Active / Q000191:economics; D018791:CD4 Lymphocyte Count; D003362:Cost-Benefit Analysis; D004608:Eligibility Determination / Q000379:methods; D005260:Female; D015658:HIV Infections / Q000188:drug therapy* / Q000276:immunology; D017048:Health Care Costs; D006801:Humans; D007194:India; D008297:Male; D008962:Models, Theoretical; D019057:Quality-Adjusted Life Years; D013019:South Africa; D014744:Vietnam; D015024:Zambia