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
