Innovations for
cost effective algorithms

Worldwide the TB incidence reduces about 2% per year, which is not sufficient to reach the targets of the End TB Plan [1]. Strategies to actively find cases and ensure prompt effective treatment exist also for high TB burden settings [2]. However, to scale up such strategies, which include screening for active TB in key populations, to a large scale, 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.

The choice for an algorithm 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 positive predictive value, and is the least amenable to setting-specific variation [3].

The use of computerized scoring of CXRs has the potential to extend the use of CXR in resource constrained settings which still face challenges of sufficient qualified staff to interpret CXR correctly, and thus has the potential to minimize the cost of TB diagnosis especially when used prior to more expensive new diagnostic tools. [4]

Innovative algorithm

Digital Chest Images are instantly available and can be interpreted by CAD or by a human reader who does not need to be in the same location by using the internet or mobile phone network connections. This makes digital CXR a rapid and relatively low cost triage tool for Xpert® eligibility also fit for use in low resource areas. This enables NTP’s to boost diagnostic output at same budgetary input (online Economics of Screening model).

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