Aids Weekly Plus
An article in News-Medical.net reports on a study about the viability of the Xpert MTB/RIF test for diagnosis of TB and multidrug resistance outside a laboratory and conducted by clinical staff with minimal training. The current, century-old TB test involves sputum smear microscopy and chest X-ray that misses 40–60 percent of cases; reports also indicate that 40 percent of individuals who receive positive test results do not return to learn their results or seek treatment. Xpert provides results in two hours for individuals with suspected drug-resistant TB and TB/HIV coinfection, improves time to starting treatment, and increases the number of individuals who begin treatment on the day of testing. The World Health Organization endorsed the Xpert test in 2011.
Professor Keertan Dheda of the Department of Medicine, University of Cape Town, and colleagues, investigated the feasibility of the Xpert test, including accuracy, failure rates, operator adherence, and user appraisal, with a nurse conducting the testing after one day of training. They compared the Xpert test to smear microscopy at five healthcare facilities in South Africa, Zimbabwe, Zambia, and Tanzania. The researchers randomly assigned 758 adults with suspected TB to same-day smear microscopy (182 culture-positive) and 744 to Xpert testing (185 culture-positive). Researchers assessed TB-related illness in culture-positive patients at the beginning of the study and after two months and six months of treatment using scoring systems that also measured quality of life, and TB signs and symptoms.
Results show the Xpert diagnosed more culture-confirmed cases of TB (83 percent) compared to microscopy (50 percent), increased same-day rate of treatment initiation, and decreased drop-out rates by half. Findings show that a non-specialist can conduct the test accurately with minimal training. Dheda contended that the Xpert test might not be ideally suited for poor resource settings, but in countries like South Africa with good clinic infrastructure and high rates of drug resistance and patient drop-out, locating Xpert at clinics in TB hotspots might be beneficial.
The full report, “Feasibility, Accuracy, and Clinical Effect of Point-of-Care Xpert MTB/RIF Testing for Tuberculosis in Primary-Care Settings in Africa: A Multicentre, Randomised, Controlled Trial,” was published online in the journal The Lancet (2013; doi:10.1016/S0140-6736(13)62073-5).