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The WHO consolidated guidelines on tuberculosis: tuberculosis preventive treatment include recommendations for the four milestones in the cascade of preventive care, namely identification of risk groups, TB screening and ruling out TB, testing for TBI, and choice and administration of the TPT regimen. The second edition of the TPT guidelines will have the same scope.
Tuberculosis (TB) is a leading cause of death from a single infectious agent, despite being largely curable and preventable. In 2019 an estimated 2.9 million of the 10 million people who fell ill with TB were not diagnosed or reported to the World Health Organization (WHO). The Political Declaration adopted by the United Nations General Assembly in September 2018 at the High-Level Meeting on the Fight Against Tuberculosis commits to, among other goals, diagnosing and treating 40 million people with TB by 2022.
Giving TPT to someone who has TB disease can delay resolution of disease and favour the emergence of drug resistance. Excluding TB disease before initiating preventive treatment is one of the critical steps in the TBI care pathway. This section proposes approaches for ruling out TB disease and diagnosing TBI in people at risk of TB according to HIV status, symptoms, household contact, other risk factors, age, TBI test results and abnormality on CXR (Fig.1).
The Global Tuberculosis Programme of the World Health Organization (WHO) gratefully acknowledges the contributions that many individuals and organizations (listed in Web Annex A) have made to the development of these guidelines.
The systematic review of the performance of an mWRD used to screen for TB among people living with HIV included 14 studies with a total of 9 209 participants (see Web Annex B, Table 16, and Web Annex C, Table 9). The Xpert MTB/RIF assay was the primary mWRD used in these studies. The prevalence of TB in the studies ranged from 1% to 26%.
CXR is recommended by WHO to be used in parallel with the W4SS where CXR is available to assist in ruling out active TB prior to initiating TPT among people living with HIV who are on ART. The GDG agreed that, due to the increased sensitivity, the evidence supported using CXR in addition to the W4SS as a parallel screening strategy in which a positive or abnormal result on either screen would indicate a referral for diagnostic evaluation.
CRP is an indicator of general inflammation that can be measured using point-of-care tests performed on capillary blood collected via finger prick. The evidence reviewed for the performance of CRP included 6 studies from Kenya, South Africa and Uganda with a total of 3 971 participants (see Web Annex B, Table 13, and Web Annex C, Table 6).
The 2020 meta-analysis of IPD included 23 studies of 16 269 participants living with HIV, all of which reviewed the accuracy of the W4SS. The studies primarily focused on pulmonary TB disease. The unweighted average TB prevalence among participants within these studies was 9.2%, ranging from 1% to 26%; and 52% of people living with HIV screened positive on the W4SS. The sensitivity of the W4SS among all people living with HIV was 83% (95% CI: 74–89) and specificity was 38% (95% CI: 25–53).
The use of CXR to screen for TB is a practice that goes back several decades. CXRs are also routinely used for triage of patients presenting to care who are displaying signs, symptoms or risk factors for TB to determine the most appropriate clinical pathway for proper evaluation. However, in many settings, the use of CXR for TB screening and triage for TB disease is limited by the unavailability of trained health personnel to interpret radiography images and by substantial intra- and inter-reader variability in its accuracy to detect abnormalities associated with TB (70–72).