WHO announces updates on new molecular assays for the diagnosis of TB and drug resistance

Globally, diagnosis of TB and rifampicin resistant TB remains a challenge with a third of people with TB and two-thirds of people with drug-resistant TB not accessing quality diagnosis and care. To address this challenge, WHO convened a meeting of an independent Guideline Development Group in December 2019, to update WHO policies on molecular assays used as initial tests for the diagnosis of TB and rifampicin resistance.

Highlights from the evidence reviewed at the Guideline Development Group meeting and presented in the Rapid Communication include: i) confirmation of high diagnostic accuracy and improved patient outcomes for the Xpert MTB/RIF assay (approved by WHO in 2010) as the initial test to diagnose pulmonary TB (i.e. replacing smear microscopy) and to simultaneously detect rifampicin resistance; ii) high diagnostic accuracy of the Xpert Ultra assay (a next-generation assay to Xpert MTB/RIF), released by the manufacturer in 2018; iii) improved diagnosis of TB and rifampicin resistance in children, using either of the assays in specific specimens such as sputum, stool, nasopharyngeal and gastric specimens; iv) improved diagnosis of TB and rifampicin resistance using either of the assays in patients with extrapulmonary TB.
 
The Rapid Communication also highlights the accuracy of a new molecular diagnostic system (called ‘Truenat’) as an initial test to diagnose pulmonary TB (i.e. replacing smear microscopy) and rifampicin resistance in sequential steps.  
 
The Rapid Communication has been released in advance of updated WHO guidelines expected in 2020, to inform national TB programmes and other stakeholders about the key implications for the diagnosis of TB and rifampicin resistance in order to allow for rapid transition and planning at country level.
 
“The diagnostic options for children and adults with TB and rifampicin resistance are increasing thanks to the engagement of manufacturers and to research that is generating new evidence. We would like to thank and acknowledge the support provided by patients, countries, technical partners, donors, civil society and other key TB stakeholders in rapidly translating research evidence into policy and practice” said Dr Tereza Kasaeva, Director of the WHO Global TB Programme. “We ask for renewed political commitment and stakeholder support in ensuring these updates are rapidly implemented. This will be critical in ensuring that the millions affected by TB and drug-resistant TB access quality care as early as possible.” 
 
Accelerated efforts to diagnose TB and rifampicin resistance are essential to end the global TB epidemic and achieve the targets of the UN high-level meeting political declaration, the WHO End TB Strategy, the UN Sustainable Development Goals, universal health coverage and triple billion targets of WHO’s General Programme of Work.

Source: WHO