TB KaSPar
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The NNS to identify one person with confirmed TB in a specific risk group is the inverse of the prevalence of detectable TB in that risk group, assuming 100% sensitivity of the screening and diagnostic tools being used.
Fig. 3 shows the potential yield of screening in a range of hypothetical risk groups with a range of relative risks of TB (assuming 100% coverage, acceptance of screening, sensitivity and specificity of screening). As illustrated in Fig. 2.2, the yield of TB screening in a specific risk group (in terms of the number of TB cases detected; y axis) depends on both the size of the risk group (i.e. the prevalence of the risk factor in the general population; x axis) and the relative risk of TB for that risk group (z axis).
The main purpose of an epidemiological assessment is to identify gaps in TB case detection and opportunities for addressing those gaps through screening. The assessment should account for potential benefits, risks and costs of systematic screening, particularly in relation to other possible interventions. The analysis should be disaggregated by age, sex and geographical location, and special attention should be paid to vulnerable groups that are at high risk for exposure and/or progression to TB disease or are likely to face barriers to accessing TB services, or both.
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:
M&E play important roles in patient care and in assessing national programmes and the global response (Fig. 11).
WHO has long recommended use of TPT for populations at risk of TB, particularly those with HIV and child household contacts of TB patients.
The fourth step in the cascade of care for PMTPT is the choice of TPT regimen and providing support to people on TPT in completing their treatment.
About one fourth of the world’s population is estimated to have been infected with M. tuberculosis (1,2).
