Digital Innovations for
New Diagnostic Pathways

Worldwide the TB case detection rate stagnates at about 65%. The efficacy of strategies to actively find cases and ensure prompt effective treatment was shown in high TB burden settings [1]. However, to scale up screening for active TB in risk groups, rapid and more affordable diagnostic pathways are required. dCXR/CAD in combination with Xpert MTB/RIF effectively responds to this need to find the missing people with TB as part of the WHO END TB Strategy.

The ideal algorithm does not yet exist. The choice will be setting specific, but generally an algorithm composed of Chest X-ray (CXR) screening followed by confirmatory testing with Xpert can achieve the lowest Number Needed to Screen and highest PPV, and is the least amenable to setting-specific variation [2].

Digital technologies such as AI that shorten the diagnostic process and facilitate early detection will increase case finding, improve treatment outcomes and interrupt the transmission of TB. CXR is widely established in TB programmes for the past decades in especially the North America and Europe, but numerous factors until recently complicated its use in low and medium resource countries. The use of computerised scoring of CXRs has the potential to extend the use of CXR in resource constrained settings which still face challenges of qualified staff to interpret CXR correctly and thus has the potential to minimise the cost of TB diagnosis especially when used in conjunction with expensive new diagnostic tools. [3]

Innovations for New Diagnostic Pathways

Digital radiology simplifies the creation of a quality image to 2 mouse clicks provided that staff is correctly trained. Images are instantly available and can be diagnosed on distance using the internet or even mobile phone network connections. In addition, artificial intelligence such as Computer Aided Detection for TB already reaches up to 94% at 84% specificity in a low HIV prevalence risk group screening program in the Philippines. Dutch R&D specialists of Thirona in cooperation with Radboud University expect CAD specificity of chest images to rise as research continues to detect also other lung diseases with the algorithm. This makes digital CXR a rapid and relatively low cost triage tool for Xpert eligibility also in low resource areas, enabling NTP’s to boost diagnostic output at same budgetary input (online Economics of Screening model). In fact Artifial Intelligence such as CAD will facilitate access also in resource constrained settings to high standards of TB care that have been available to Western Europe and North America for decades (e.g. mobile screening using radiology).

The above cost indications for dCXR/CAD and Xpert include salary cost (LMIC), cartridge cost and provisions for maintenance for dCXR and Xpert system.

TB Innovations Summit NYC 2018

The TB Innovation Summit was forward-looking and solutions-oriented with the tagline for this event being "Our Journey to End TB Begins Now”. The event also provided a platform for companies and organizations to announce new commitments for TB ahead of the UN HLM. At this summit preceding the historic UN General Assembly on TB in September 2018, Computer Aided Detection for TB (CAD) was selected and presented as one of the key innovations for early detection.

WHO guidelines on CXR

  • Important triaging tool for pulmonary conditions including TB
  • Useful to decide who should be tested with Gene Xpert MTB/RIF
  • Most sensitive TB screening tool and therefore recommended as the first screening test in prevalence surveys
  • Optimal first screening tool for screening in high risk groups.
  • Recommended tool to rule out TB before initiating LTBI treatment (in well-resourced countries with TB incidence less than 100/100.000)
  • Useful diagnostic tool for non-bacteriologically confirmed TB, for example in PLHIV and children.

Case detection in children

It is more difficult to diagnose TB in children than in adults as they are less likely to have the classical signs and symptoms of the disease, like couch. Children have usually less bacilli in the sputum and the younger children often cannot produce a specimen for microscopy. Therefore CXR plays an important role in TB diagnosis in children. The intended use of CAD4TB as from the 2018 version 6 was enlarged to serve subjects as from 4 years of age.