WHO Meeting Report of a Technical Expert Consultation:
Non-inferiority analysis of Xpert MTB/RIF Ultra compared to Xpert MTB/RIF
On 20 January 2017, World Health Organization (WHO) convened a Technical Expert Consultation to assess the performance of the new Ultra assay compared with the Xpert MTB/RIF assay in a multi-centre study diagnostic accuracy study coordinated by FIND in ten study sites in eight countries. The Technical Expert Group found that the Ultra assay is non-inferior to the Xpert MTB/RIF assay for the detection of Mycobacterium tuberculosis (MTB) and for the detection of rifampicin resistance. This means that the new Ultra cartridge is at least as good for the detection of MTB and rifampicin resistance as Xpert MTB/RIF.
In certain populations, the Ultra performs better for MTB detection especially for individuals whose specimens are frequently paucibacillary. The Ultra cartridge showed better performance for the detection of MTB in smear-negative culture-positive specimens, paediatric specimens, extra-pulmonary specimens (notably cerebrospinal fluid) and in testing smear-negative culture-positive specimens from HIV-positive individuals.
The current WHO recommendations for the use of Xpert MTB/RIF now also apply to the use of Ultra as the initial diagnostic test for all adults and children with signs and symptoms of TB and in the testing of selected extrapulmonary specimens (CSF, lymph nodes and tissue specimens).