Abstract
ObjectiveTo investigate the impact of introducing a rapid test as the first-line diagnostic test for drug-sensitive tuberculosis in Cape Town, South Africa.MethodsXpert® MTB/RIF (Xpert®), an automated polymerase-chain-reaction-based assay, was rolled out between 2011 and 2013. Data were available on 102 007 adults treated for pulmonary tuberculosis between 2010 and 2014. Tuberculosis notification rates per 100 000 population were calculated for each calendar year and for each year relative to the test roll-out locally, overall and by bacteriological confirmation. Empirical treatment was defined as treatment given without bacteriological confirmation by Xpert®, sputum smear microscopy or sputum culture.FindingsBetween 2010 and 2014, the proportion of human immunodeficiency virus (HIV)-negative patients treated empirically for tuberculosis declined from 23% (2445/10 643) to 11% (1149/10 089); in HIV-positive patients, it declined from 42% (4229/9985) to 27% (2364/8823). The overall tuberculosis notification rate decreased by 12% and 19% among HIV-negative and HIV-positive patients, respectively; the rate of bacteriologically confirmed cases increased by 1% and 3%, respectively; and the rate of empirical treatment decreased by 56% and 49%, respectively. These changes occurred gradually following the test’s introduction and stabilized after 3 years.ConclusionRoll-out of the rapid test in a setting with a high prevalence of pulmonary tuberculosis and HIV infection was associated with a halving of empirical treatment that occurred gradually after the test’s introduction, possibly reflecting the time needed for full implementation. More than a quarter of HIV-positive patients with tuberculosis were still treated empirically, highlighting the diagnostic challenge in these patients.
Highlights
Sputum smear microscopy is traditionally the first-line diagnostic test for tuberculosis in countries without routine access to the gold standard: sputum culture. This approach is limited by low sensitivity, among patients who test positive for the human immunodeficiency virus (HIV), and is associated with diagnostic delays, underdiagnosis and empirical treatment.[1]
In South Africa, roll-out of this test as the primary test in a new tuberculosis diagnostic algorithm started in March 2011 – it was completed in Cape Town in February 2013.17 In this study, we evaluated the impact of the test roll-out in Cape Town on the diagnosis of patients with drug-sensitive tuberculosis, stratified by HIV status
Research Rapid diagnostic test roll-out, South Africa diagnosis of pulmonary tuberculosis was generally based on sputum smear microscopy, with sputum culture reserved for patients who remained symptomatic despite negative microscopy findings or who were being retreated
Summary
Sputum smear microscopy is traditionally the first-line diagnostic test for tuberculosis in countries without routine access to the gold standard: sputum culture. This approach is limited by low sensitivity, among patients who test positive for the human immunodeficiency virus (HIV), and is associated with diagnostic delays, underdiagnosis and empirical treatment.[1] The Xpert® MTB/RIF (Xpert®) test (Cepheid, Sunnyvale, United States of America) is an automated, cartridge-based, rapid molecular diagnostic test for Mycobacterium tuberculosis and its resistance to rifampicin.[2] The test detects the rpoB gene of M. tuberculosis, including mutations that encode rifampicin resistance, using a realtime polymerase chain reaction and takes less than 2 hours. When one of the original modelling papers was modified to align its results with one of the trials, the predicted decline in tuberculosis incidence decreased from 6% to 1.6%.10,15 Modelling the effect of the test in India produced similar results.[16]
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