Screening

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:

The two complementary approaches for improving early detection of TB are illustrated in Fig. 2.1 The primary approach is to optimize the patient-initiated pathway to TB diagnosis and treatment (for details see 2.1.1). This approach does not constitute screening and is a passive form of case detection.

This document provides practical guidance on translating WHO’s recommendations for screening into a national or local strategy with clear objectives, prioritization of risk groups and definition of the most appropriate screening approaches.

The specific objectives are:

The production of the WHO consolidated guidelines on tuberculosis. Module 2: screening was coordinated and written by Cecily Miller, with support from Annabel Baddeley, Dennis Falzon and Matteo Zignol, under the overall direction of Tereza Kasaeva, Director of the World Health Organization (WHO) Global Tuberculosis Programme. The WHO Global Tuberculosis Programme gratefully acknowledges the contribution of all experts involved in producing these guidelines¹.

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

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).