title: The cost-effectiveness of monitoring strategies for antiretroviral therapy of HIV infected patients in resource-limited settings: software tool.
abstract: BACKGROUND
  The cost-effectiveness of routine viral load (VL) monitoring of HIV-infected patients on antiretroviral therapy (ART) depends on various factors that differ between settings and across time. Low-cost point-of-care (POC) tests for VL are in development and may make routine VL monitoring affordable in resource-limited settings. We developed a software tool to study the cost-effectiveness of switching to second-line ART with different monitoring strategies, and focused on POC-VL monitoring.
  
  
  METHODS
  We used a mathematical model to simulate cohorts of patients from start of ART until death. We modeled 13 strategies (no 2nd-line, clinical, CD4 (with or without targeted VL), POC-VL, and laboratory-based VL monitoring, with different frequencies). We included a scenario with identical failure rates across strategies, and one in which routine VL monitoring reduces the risk of failure. We compared lifetime costs and averted disability-adjusted life-years (DALYs). We calculated incremental cost-effectiveness ratios (ICER). We developed an Excel tool to update the results of the model for varying unit costs and cohort characteristics, and conducted several sensitivity analyses varying the input costs.
  
  
  RESULTS
  Introducing 2nd-line ART had an ICER of US$1651-1766/DALY averted. Compared with clinical monitoring, the ICER of CD4 monitoring was US$1896-US$5488/DALY averted and VL monitoring US$951-US$5813/DALY averted. We found no difference between POC- and laboratory-based VL monitoring, except for the highest measurement frequency (every 6 months), where laboratory-based testing was more effective. Targeted VL monitoring was on the cost-effectiveness frontier only if the difference between 1st- and 2nd-line costs remained large, and if we assumed that routine VL monitoring does not prevent failure.
  
  
  CONCLUSIONS
  Compared with the less expensive strategies, the cost-effectiveness of routine VL monitoring essentially depends on the cost of 2nd-line ART. Our Excel tool is useful for determining optimal monitoring strategies for specific settings, with specific sex-and age-distributions and unit costs.
authors: Institute of Social and Preventive Medicine (ISPM), University of Bern, Bern, Switzerland.
authors: Janne
authors: J
authors: Estill
authors: Institute of Social and Preventive Medicine (ISPM), University of Bern, Bern, Switzerland.
authors: Luisa
authors: L
authors: Salazar-Vizcaya
authors: Institute of Social and Preventive Medicine (ISPM), University of Bern, Bern, Switzerland.
authors: Nello
authors: N
authors: Blaser
authors: Institute of Social and Preventive Medicine (ISPM), University of Bern, Bern, Switzerland; Centre for Infectious Disease Epidemiology and Research, University of Cape Town, Cape Town, South Africa.
authors: Matthias
authors: M
authors: Egger
authors: Institute of Social and Preventive Medicine (ISPM), University of Bern, Bern, Switzerland.
authors: Olivia
authors: O
authors: Keiser
mesh_terms: D000293:Adolescent; D000328:Adult; D023241:Antiretroviral Therapy, Highly Active / Q000191:economics; D003362:Cost-Benefit Analysis / Q000379:methods*; D018450:Disease Progression; D005260:Female; D015658:HIV Infections / Q000188:drug therapy* / Q000821:virology; D017048:Health Care Costs; D006295:Health Resources; D006801:Humans; D008297:Male; D008875:Middle Aged; D008962:Models, Theoretical; D012984:Software; D017211:Treatment Failure; D016896:Treatment Outcome; D055815:Young Adult