CXR is useful for screening people living with HIV for TB. It is currently recommended by WHO for use in parallel with W4SS for ruling out TB disease before initiating TPT. Similarly, CXR can be used in parallel with W4SS to screen for TB disease, a positive or abnormal result on either screen indicating referral for diagnostic evaluation. CXR can be used to either add to the sensitivity of W4SS (in a sequential negative algorithm) or to improve the pre-test probability of TB among those who screen positive for symptoms (in a sequential positive algorithm) (see 3.2). Reading modalities of “any abnormality” or “abnormality suggestive of TB” can be used, depending on the context, the availability of radiological expertise, resources and a preference for higher sensitivity or higher specificity.
Table 5.3 shows the diagnostic accuracy of CXR combined with W4SS in different sub-populations of people living with HIV. A combined screening strategy of W4SS and CXR offers a significant improvement in sensitivity, particularly for screening outpatients enrolled in ART care, over W4SS alone, although with lower specificity (W4SS: sensitivity 53%, specificity 70%). However, in some subgroups like inpatients and people with advanced HIV disease the specificity is very low.
For more detail, see Web Annex B of the screening guidelines.
ᵃ Indicator of advanced HIV disease