Abstract
The Xpert MTB/RIF assay was introduced for timely and accurate detection of tuberculosis (TB). The aim of this study was to determine the diagnostic accuracy and turnaround time (TAT) of Xpert MTB/RIF assay in clinical practice in South Korea. We retrospectively reviewed the medical records of patients in whom Xpert MTB/RIF assay using sputum were requested. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for the diagnosis of pulmonary tuberculosis (PTB) and detection of rifampicin resistance were calculated. In addition, TAT of Xpert MTB/RIF assay was compared with those of other tests. Total 681 patients in whom Xpert MTB/RIF assay was requested were included in the analysis. The sensitivity, specificity, PPV and NPV of Xpert MTB/RIF assay for diagnosis of PTB were 79.5% (124/156), 100.0% (505/505), 100.0% (124/124) and 94.0% (505/537), respectively. Those for the detection of rifampicin resistance were 57.1% (8/14), 100.0% (113/113), 100.0% (8/8) and 94.9% (113/119), respectively. The median TAT of Xpert MTB/RIF assay to the report of results and results confirmed by physicians in outpatient settings were 0 (0–1) and 6 (3–7) days, respectively. Median time to treatment after initial evaluation was 7 (4–9) days in patients with Xpert MTB/RIF assay, but was 21 (7–33.5) days in patients without Xpert MTB/RIF assay. Xpert MTB/RIF assay showed acceptable sensitivity and excellent specificity for the diagnosis of PTB and detection of rifampicin resistance in areas with intermediate TB burden. Additionally, the assay decreased time to the initiation of anti-TB drugs through shorter TAT.
Highlights
And accurate detection of tuberculosis (TB) is important for the timely initiation of treatment and prevention of TB transmission
We calculated the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the Xpert MTB/RIF assay regarding the patients with positive Xpert MTB/RIF assay as having pulmonary TB
As an initial diagnostic method of M.TB, the accuracy and speed of the Xpert MTB/RIF assay have been demonstrated in previous studies
Summary
And accurate detection of tuberculosis (TB) is important for the timely initiation of treatment and prevention of TB transmission. Conventional methods for the diagnosis of TB have limitations in terms of early and accurate detection. In South Korea, confirmation of mycobacterial culture and confirmation of conventional drug susceptibility tests (DST) takes approximately 43 days (19–77), and 91.5 days (51–170), respectively. The Xpert MTB/RIF assay, using RT-PCR for the TB specific rpoB gene, was validated for simple and rapid diagnosis of TB [5]. Detection of the rpoB gene is known to be specific for TB diagnosis, and mutation of the rpoB gene is associated with resistance to rifampicin (RIF). Using probes complementary to the rpoB gene, the Xpert MTB/RIF assay can identify M. In South Korea, the Xpert MTB/RIF assay was adopted for the diagnosis of TB since 2011
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