Modelling for the WHO 2013 Guidelines for Use of Antiretrovirals

© WHO

    
In July 2013 the WHO released major new guidance on the use of ART for HIV infection. The revised guidelines differed in content and format to previous guidelines as they focused on the programmatic aspects of implementing policy changes and provide a guide to staged and prioritized implementation. To support these efforts, mathematical modelling work has been introduced into the development of the guidelines for the first time.

Background

Between November 2011 and January 2013, the HIV Modelling Consortium worked closely with the World Health Organisation in preparation for their 2013 consolidated guidelines on the use of anti-retrovirals. The revised guidelines are aimed to be of particular benefit to national programme managers and policymakers who are responsible for decisions regarding resource allocation to ensure maximum impact and benefit from ARVs. 

Approach

In order to best address the specific questions raised by the WHO, the HIV Modelling Consortium led a large collaboration between over sixty mathematical modellers and health economists. The group included leading researchers from many international institutions such as Imperial College London, the London School of Hygiene and Tropical Medicine, Harvard School of Public Health, Princeton University, University of York, Stellenbosch University and the Erasmus Medical Centre. 

Objectives

  1. To inform the programmatic section of the guidelines, i.e. in country priority setting regarding impact and cost effectiveness of expanded access to ART in different populations in concentrated and generalized epidemics
  2. To provide an additional data source in risk-benefit and feasibility assessments in making recommendations for individual PICOTs.

Modelling Questions

The HIV Modelling Consortium established a number of working groups to model different scenarios for the WHO Guidelines. 

  • "Side by side" comparison of expanding treatment at CD4>350 for specific populations, including:
  1. Whole population
  2. Pregnant women (stratified for breastfeeding and non-breastfeeding)
  3. Serodiscordant couples
  4. Key populations (drug users, sex workers)
  5. Hepatitis B and C co-infection
  6. Tuberculosis co-infection
  • Monitoring strategies (denotes permutation of CD4 and viral load measurement, choice of thresholds, and decision-rules used)
  1. What are the most cost effective treatment monitoring strategies for treatment and prevention outcomes in adults?
  2. What are the most cost effective treatment monitoring strategies for treatment and prevention outcomes in children?

Outcomes

The Consortium held an intensive workshop meeting in London, UK in November 2012, which reviewed the culmination of multiple research threads in response to questions raised by the WHO in relation to the development of the guidelines.  A report was not developed for this meeting as the content from the meeting was submitted directly to the WHO for consideration. The submitted reports included:

  1. When To Start ART: A Modelling Case Study of Impact of Earlier ART Eligibility in South Africa
  2. The Cost and Impact of Alternative Strategies for Monitoring Adult Patients on ART
  3. The Cost and Impact Of Alternative Strategies for Monitoring Child Patients on ART
  4. Briefing note on the epidemiological benefits of early antiretroviral therapy for adults coinfected with HIV and hepatitis B virus or hepatitis C virus

Resources

In addition to the reports listed above, a series of publications have now been released in relation to this modelling effort (all of which are available to download from our publications page):
  • Eaton and Menzies et al. Health benefits, costs and cost-effectiveness of earlier eligibility for adult antiretroviral therapy and expanded treatment coverage: a combined analysis of 12 mathematical models. Lancet Global Health 2014; 2: e23-34.
  • Keebler and Revill et al. Cost effectiveness of different strategies to monitor adults on antiretroviral treatment: a combined analysis of three mathematical models. Lancet Global Health 2014; 2: e35-43.
  • A special collection of articles in the journal AIDS, entitled Modelling the Cost and Consequences of the 2013 WHO Consolidated Guidelines.  Copies of the supplement are available from the HIV Modelling Consortium, if you would be interested in receiving a copy please email Ellen McRobie - e.mcrobie(at)imperial.ac.uk