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WHO/Stop TB Partnership

CheckTB! liaises with WHO and Stop TB Partnership team members for the design of innovative case detection projects and operational research to further validate the effectiveness of digital radiology and CAD (e.g. in systematic screening and TB prevalence surveys). These field data can serve to perform comparative analyses and to update WHO guidelines and recommendations on the use of chest X-rays and Artificial Intelligence such as CAD for instance in combination with Xpert® MTB/RIF.

At various STOP TB Partnership meetings the high sensitivity of Chest X-ray was illustrated by findings in the TB prevalence surveys in Viet Nam, Cambodia, Ethiopia, Ghana, Kenya and Rwanda. The fact that screening on symptoms only can result in missing more than 50% of the TB cases, now makes Chest X-ray with high sensitivity levels a mandatory part of any TB prevalence survey, as mentioned in the WHO Workshops on TB Prevalence Surveys. CAD4TB is included in the WHO Compendium of Innovative Health Technologies for Low-Resource Settings. Additionally, it was included in the WHO’s 2017 policy paper: “Global Investment in Tuberculosis Research and Development: Past, Present & Future” as development completed. WHO/TB Reach supports various projects that incorporate CAD4TB.


WHO Chest radiography in tuberculosis detection; by Dr Knut Lönnroth

WHO recommendations and guidance on programmatic approaches; Octiber 2016

Systematic screening in high risk groups is on the agenda for high burden countries too – rapid and sensitive screening tool needed.

  • Prevalence surveys: Chest X-ray much higher sensitivity than symptom screening
  • Rapid, highly sensitive molecular test improves possibility to rule out TB in persons with CXR abnormalities
  • Scale-up of latent TB management – need to rule out active TB
  • General imaging services including X-ray availability has increased
  • Advances in digital technology: better quality, lower running costs, better storage, opportunities for telemedicine, computer aided reading (CAD4TB)

Stop TB Partnership, October 2015

A Paradigm Shift 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”.

  • Limitations on the wider use of Chest X-rays, such as non-availability at peripheral health facilities and the difficulty of interpreting results, even by trained physicians, need to be addressed
  • Research is needed to identify innovative ways to enhance the ability of clinicians, including non-physicians, to interpret Chest X-rays accurately
  • Chest X-ray plays an important role in the diagnostics of TB and non-TB chest diseases common among people living with HIV
  • Chest X-rays play a significant role in shortening delays in diagnosis
  • Avoiding films by using digital Chest X-ray is an important advantage; Digital technology has a potential to solve most CXR problems
Source: "Improving the diagnosis and treatment of smear-negative pulmonary and extrapulmonary tuberculosis among adults and adolescents" WHO /HTM /TB /2007.379

WHO Radiography Factsheet

X-ray based examinations are crucial in a variety of medical setting and at all major levels of health care. Chest radiography, or chest X-ray (CXR) is a rapid imaging tool that allows for easy identification of lung abnormalities. CXR is an essential tool for early detection of tuberculosis (TB), and therefore fundamental to achieving the targets set out in WHO’s End TB Strategy. CXR has high sensitivity, but limited specificity for detecting pulmonary TB. It is therefore especially suitable for TB screening and triaging. Recommendations on CXR in TB detection are included in several WHO policies, summarized below.

An essential tool to end TB

CXR IS A SENSITIVE TOOL FOR SCREENING FOR ACTIVE TB
(Reference: Guidelines on systematic screening for active TB)

  • CXR has much higher sensitivity for pulmonary TB than screening for TB symptoms
  • CXR can also be used as a supplementary diagnostic tool, although the specificity is low. A bacteriologically-confirmed diagnosis is always preferred

AN ABNORMAL CXR IS AN INDICATION FOR FULL DIAGNOSTIC EVALUATION
(Reference: The International Standards of TB Care)

  • All patients with unexplained findings suggestive of tuberculosis on CXR should be evaluated for TB with a bacteriological diagnostic test

CXR IS AN IMPORTANT TOOL FOR CHILDHOOD TB DIAGNOSIS
(Reference: Guidelines on childhood TB)

  • CXR is useful in the diagnosis of pulmonary and extrapulmonary TB in children, in combination with history, evidence of TB infection and microbiological testing

CXR CAN IMPROVE THE EFFICIENCY OF XPERT MTB/RIF USE
(Reference: Implementation manual on Xpert MTB/RIF)

  • CXR and further clinical assessment can be used to triage who should be tested with Xpert MTB/RIF in order to reduce the number of individuals to be tested with Xpert MTB/RIF, as well as to improve pre-test probability of TB

CXR CAN ASSIST THE DIAGNOSIS OF TB AMONG PEOPLE LIVING WITH HIV
(Reference: Consolidated guidelines on the use of ARV drugs for treating and preventing HIV infection (forthcoming publication))

  • CXR can assist the diagnosis of TB among people living with HIV. It is particularly useful to rule out TB disease before the provision of treatment for latent TB

CXR HELPS RULE OUT ACTIVE TB BEFORE TREATING LATENT TB INFECTION
(Reference: Guidelines on management of latent TB infection)

  • Symptom screening and CXR should be done to exclude active TB before initiating treatment of latent TB infection
  • Individuals with TB symptoms or any radiological abnormality should be investigated further for active TB and other conditions

CXR IS AN ESSENTIAL TECHNOLOGY FOR PREVALENCE SURVEYS
(Reference: Guidelines on TB prevalence surveys)

  • CXR is a necessary screening tool to identify survey participants eligible for bacteriological examination

Key actions moving forward

The following actions were taken by WHO in 2016

  • Prepare an operational guide on chest radiography and organize a global consultation for its finalization
  • Perform a review of available evidence on computer-aided radiographic TB detection (CAD), and organize a scoping meeting to determine if WHO guidelines should be developed and determine the research needs