Operational Handbooks

Annex 2 Comparative performance of algorithms for the general population and high-risk groups (not including people living with HIV)

The tables below contain modelled estimates of the performance and outcomes of the 10 screening algorithms described above, when applied to a population of 100,000 people being screened, across three different TB prevalence settings: 0.5%, 1% and 2%. 

1 – Screening with cough

2 – Parallel screening with cough and CXR

3 – Sequential positive serial screening with cough and CXR

4 – Sequential negative serial screening with cough and CXR

5 – Screening with any TB symptom

5.1 Introduction

Since 2011, WHO has recommended that people living with HIV be systematically screened for TB disease at each visit to a health facility. The recommendation is based on the high risk of this group for TB and mortality and a lingering gap in case detection in this population. In 2019, people with HIV were at 18 times greater risk for incident TB than people without HIV and close to one third of deaths from AIDS were due to TB (2). Only 56% of the total estimated number of HIV-positive incident TB cases were detected in 2019 (2).

4.1 Considerations in selecting and using CAD for screening in TB programmes

CAD technologies for automated reading of digital CXR for TB detection offer a promising solution for high-TB burden countries; however, selecting the appropriate CAD product for a particular setting can be complex. When selecting a CAD product, TB programmes and implementers should consider multiple aspects of the technology and its interface with existing infrastructure, including: