Risk group screening Print

Systematic screening of high risk populations and prompt access to appropriate treatment are crucial to reduce the TB burden. The WHO guidelines for Systematic Screening for active TB include Chest X-ray as a sensitive screening tool.

Stop TB partnership

A Paradigm Shift is needed in the way we fight TB

“Unless we speak about Active Case Finding, X-ray, contacts, prevention (amongst others) we will not reach our targets”.

WHO recommends that priority be given to populations with:

ü High TB prevalence (risk factor profile and/or poor access/delay);

ü High risk of severe negative consequences if diagnosis is missed;

ü High transmission risk.

 

ACF innovations to support Paradigm Shift implementation

  • Systematic screening aims to detect more cases, and to detect them early.
  • Innovations in diagnostic imaging have the potential to make screening in high risk groups faster and more sustainable.
  • Digital Chest X-ray (dCXR) with Computer Aided Detection (CAD) as a rapid and automated triage test before Xpert® MTB/RIF can significantly reduce screening cost.
  • To scale up ACF in risk groups rapid and more affordable diagnostic pathways are required
  • Relatively high cost and 2 hours processing time still limit the update of Xpert as point-of-care test
  • CAD4TB automatically scores CXR between 0 -100 on abnormalities consistent with TB in 1 minute and surpasses trained human reader performance
  • These innovations support the Paradigm Shift implementation through new diagnostic pathways to detect more TB cases earlier at much lower cost

 

Active case finding in risk groups

Previous: symptoms, microscopy & culture: 15-30 days
New: symptoms, dCXR/CAD & molecular test: 2.5 hours

Assuming 3.5% TB prevalence in high risk groups; this could be applicable for high risk populations such as PLWH, diabetics, mine workers, inmates, armed forces, refugee camps with a relatively low number needed to screen in order to diagnose 1 active TB case.

Double diagnostic output at same input

In below tables the economics of TB screening for 2 algorithms are compared. This cost and yield simulation can be customized in the online model Economics of Screening on this site.

Different settings can require other pathways resulting in different economics; costs include depreciation, maintenance, CAD “Pay per use” fee, labor and logistics; assumed Xpert “failed test rate” 10%; daily throughput 100 clients; 1$ = 0.9 €.