Overview

The majority of IGRA studies have been performed in high-income countries and mere extrapolation to low- and middle-income settings with high background TB infection rates is not appropriate. Systematic reviews have suggested that IGRA performance differs in high- versus low TB and HIV incidence settings, with relatively lower sensitivity in high-burden settings. The WHO Stop TB Department (WHO-STB) therefore commissioned systematic reviews on the use of IGRAs in low- and middle-income countries, in pre-defined target groups, with funding support from the UNICEF/UNDP/World Bank/WHO Special Programme for Research and Training in Tropical Diseases (TDR) and TREAT-TB/The Union. The target groups and major findings of the GRADE evidence synthesis process are summarised below.

This Policy Statement applies to the use of commercial IGRAs in low- and middle-income countries only. Several international guidelines on IGRA use in high-income countries are available. This Policy Statement is not intended to apply to high-income countries or to supersede their national guidelines.

Contents

• Executive summary
• Acknowledgements
• Declarations of Interest
• 1. Background
• 2. Methods
  • 2.1 Evidence synthesis
  • 2.2 Decision-making during the Expert Group meeting and external review
  • 2.3 Scope of the policy guidance
• 3. Evidence base for policy formulation
  • 3.1 Use of IGRAs in diagnosis of active TB
  • 3.2 Use of IGRAs in children
  • 3.3 Use of IGRAs for the diagnosis of LTBI in HIV-infected individuals
  • 3.4 Use of IGRAs for screening of health care workers
  • 3.5 Use of IGRAs in contact screening and outbreak investigations
  • 3.6 The predictive value of IGRAs for incident active TB
• 4. Operational aspects on the use of IGRAs
• 5. Overall conclusions
• 6. Implications for further research
• 7. GRADE tables
• 8 Selected references
• Annex 1 List of Participants- Expert Group meeting
• Annex 2 List of Participants- STAG-TB

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