WHO evaluation of centralized assays for detection of TB and of resistance to rifampicin and isoniazid
24 October 2019 | Geneva - The TB diagnostic pipeline has advanced significantly in the last decade, with promising tools being developed in recent years. Among the newest diagnostic tools emerging from the TB diagnostic pipeline are multi-disease high throughput centralized assays which permit upfront TB detection as well as the identification of isoniazid and rifampicin resistance. The World Health Organization convened a Technical Expert Group to assess the results of an external laboratory validation of four novel centralized TB assays: the Abbott RealTime MTB and MTB RIF/INH assays, the Roche cobas® MTB and MTB-RIF/INH assays, the Hain FluoroType® MTBDR assay, and the BD MAXTM MDR-TB assay.
“As we accelerate efforts to reach 40 million people with TB care by 2022 as outlined in the UN High Level Meeting political declaration, we need newer and more effective diagnostic tools. The new diagnostic platforms assessed by WHO show potential for higher throughput and multi-disease testing beyond TB, and offer opportunities for integration of laboratory services across diseases such as TB, HIV and hepatitis, says Dr Tereza Kasaeva, Director of the WHO Global TB Programme. “These platforms in combination with reliable sample transport systems, can increase access to reliable diagnostic testing for more patients- closing gaps in care.’
The WHO Technical Expert Group concluded that all the centralized assays assessed with the resistant strain panel showed similar or increased accuracy for the detection of tuberculosis and resistance to rifampicin compared to the current WHO endorsed rapid diagnostic test - Xpert MTB/RIF. In addition, all centralized assays can detect resistance to isoniazid. The group also recommended that countries be supported in undertaking programme-based operational research that would help produce evidence to inform policy recommendations.
The deliberations of the WHO Technical Expert Group were informed by an external laboratory validation, conducted by the Foundation for Innovative New Diagnostics (FIND). The evaluation compared the performance of these platforms using a well-defined strain panel to determine the analytical sensitivity for M. tuberculosis complex (MTBC) and resistance to rifampicin and isoniazid. These preliminary results warrant further phase 2 clinical validation studies on specimens from persons with presumptive TB.
“Increasing access to molecular tests for TB, including drug susceptibility testing, is a key component of the global response to the TB epidemic, said “Dr Catharina Boehme, Chief Executive Officer, FIND. The high throughput platforms allow for isoniazid (in addition to rifampicin) testing to refine treatment choice at time of diagnosis, which will help improve patient outcomes. Given the polyvalent nature of the platforms, countries can use them for integrated and cost-effective infectious disease testing, notably HIV viral load, TB and hepatitis testing on the same instrument.”
The operational assessment of the platforms demonstrated that implementation considerations will depend on many factors including sample transport and laboratory infrastructure, sample testing volume, drug resistance prevalence and the need for parallel testing of other pathogens.
Source: WHO
