Xpert test for TB proven fast and effective in developing country settings

4 May 2011

The effectiveness of the Cepheid Xpert MTB/RIF test for tuberculosis and rifampicin resistance in realistic healthcare field conditions has been reported in a study in The Lancet.

 The study demonstrates that the test can effectively be used in low-resource settings to simplify early and accurate diagnosis of patients. The potential impact is a reduction in the morbidity associated with diagnostic delay, dropout and mistreatment.

The study was published online on 19 April 2011 and in volume 377 on 30 April 2011. One of the authors, Prof. Mark Nicol of the University of Cape Town (South Africa) who contributed to this study, is a European and Developing Countries Clinical Trials Partnership (EDCTP) Senior Fellow.

EDCTP was created in 2003 as a European response to the global health crisis caused by the three main poverty-related diseases (PRDs) of HIV/AIDS, tuberculosis and malaria. Currently EDCTP is a partnership between 14 European Union member states plus Norway and Switzerland with 47 sub-Saharan African countries.

The aim of the programme is to accelerate the development of new or improved drugs, vaccines and microbicides against HIV/AIDS, malaria and tuberculosis through promoting the integration of national programmes of EDCTP European Member States and development of a genuine partnership with African counterparts.

Professor Mark Nicol of the University of Cape Town has conducted a study on the impact of the test at clinic and patient level: The impact of rapid genotypic detection of multi-drug resistant tuberculosis on treatment outcome in a semi-rural region of South Africa. In other studies the test showed high sensitivity in diagnosing TB in both smear-positive as well as smear-negative, culture-positive individuals including detection of the presence of rifampicin resistance.

This cluster randomised study aimed to determine the impact of rapid testing with Xpert MTB/RIF when compared to the routine diagnostic algorithm. The primary impact outcomes to be assessed were the time between the first presentation to clinic of a patient with symptoms and the start of appropriate treatment for TB and, secondly, the proportion of patients in each arm with undiagnosed TB two months after the first TB test.

One of the tests is a cartridge-based, automated diagnostic test that can identify Mycobacterium tuberculosis (MTB) and resistance to rifampicin (RIF) called the GeneXpert MTB/RIF. This test utilises a real time polymerase chain reaction (PCR) amplification system that processes an integrated specimen and is design ed for use at or close to the point of care.
Already, the preliminary results of this study formed a substantial component of a report submitted to the WHO Strategic and Technical Advisory Group (STAG) for Tuberculosis that endorsed the use of GeneXpert to diagnose TB in December 2010. The National Health Laboratory Service of South Africa is evaluating the possibilities of rolling out GeneXpert testing for routine services. The data from this study will be central to informing this policy decision.
The project has established working relationships with the Foundation for Innovative New Diagnostics (FIND) and the grantee and his team are consortium members of the TB Clinical Diagnostics Research Consortium led from Johns Hopkins University of USA. The team are also co-investigators on the EDCTP sponsored TB-NEAT consortium led by Professor Keertan Dheda. Funding from the Wellcome Trust will allow extension of the project to a second laboratory site and, in particular, to the follow up period beyond the term of this EDCTP grant.
The overall study of the effectiveness of the test comprised sites in South Africa, Uganda, Azerbaijan, India, Philippines and Peru. It was funded by the Foundation for Innovative New Diagnostics, the Bill & Melinda Gates Foundation, the European and Developing Countries Clinical Trials Partnership, the Wellcome Trust and the UK Department for International Development.

Further information

1. Boehme CC, et al. Feasibility, diagnostic accuracy, and effectiveness of decentralised use of the Xpert MTB/RIF test for diagnosis of tuberculosis and multidrug resistance: a multicentre implementation study. The Lancet, Volume 377, Issue 9776, Pages 1495-1505, 30 April 2011. doi:10.1016/S0140-6736(11)60438-8. www.thelancet.com/journals/lancet/article/PIIS0140-6736(11)60438-8/fulltext

2. Information on the Xpert test from Cepheid: www.cepheid.com


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