Abstract
BackgroundDiagnosis of pulmonary tuberculosis (TB) among human immunodeficiency virus (HIV) patients remains complex and demands easy to perform and accurate tests. Xpert®MTB/RIF (MTB/RIF) is a molecular TB diagnostic test which is rapid and convenient; the test requires minimal human resources and reports results within two hours. The majority of performance studies of MTB/RIF have been performed in high HIV burden settings, thus TB diagnostic studies among HIV patients in low HIV prevalence settings such as Peru are still needed.Methodology/Principal FindingsFrom April 2010 to May 2011, HIV-positive patients with high clinical suspicion of TB were enrolled from two tertiary hospitals in Lima, Peru. Detection of TB by MTB/RIF was compared to a composite reference standard Löwenstein-Jensen (LJ) and liquid culture. Detection of rifampicin resistance was compared to the LJ proportion method. We included 131 patients, the median CD4 cell count was 154.5 cells/mm3 and 45 (34.4%) had TB. For TB detection among HIV patients, sensitivity of MTB/RIF was 97.8% (95% CI 88.4–99.6) (44/45); specificity was 97.7% (95% CI 91.9–99.4) (84/86); the positive predictive value was 95.7% (95% CI 85.5–98.8) (44/46); and the negative predictive value, 98.8% (95% CI 93.6–99.8) (84/85). MTB/RIF detected 13/14 smear-negative TB cases, outperforming smear microscopy [97.8% (44/45) vs. 68.9% (31/45); p = 0.0002]. For rifampicin resistance detection, sensitivity of MTB/RIF was 100% (95% CI 61.0–100.0) (6/6); specificity was 91.0% (95% CI 76.4–96.9) (30/33); the positive predictive value was 66.7% (95% CI 35.4–87.9) (6/9); and the negative predictive value was 100% (95% CI 88.7 –100.0) (30/30).Conclusions/SignificanceIn HIV patients in our population with a high clinical suspicion of TB, MTB/RIF performed well for TB diagnosis and outperformed smear microscopy.
Highlights
Tuberculosis (TB) is the leading cause of death in human immunodeficiency virus (HIV) infected patients [1]
We evaluated the performance of MTB/RIF in HIV-positive adult patients with high clinical suspicion of pulmonary TB in two sites in Lima, a setting that has one of the highest TB and multidrug resistant tuberculosis (MDR-TB) rates in the Americas, as well as low (,3%) HIV prevalence in the general population
The proportion of TB per site was 45.1% at Hospital Nacional Hipolito Unanue (HNHU) and 27.5% at Instituto de Medicina Tropical Alexander von Humboldt (IMTAvH)
Summary
Tuberculosis (TB) is the leading cause of death in human immunodeficiency virus (HIV) infected patients [1]. Several new TB diagnostic tests have recently been developed; those require further evaluation among HIV infected patients. These new diagnostic tests should be accurate, provide results in a time frame that allows efficient treatment decision-making without increasing the demand of the already scarce human resources available in countries affected by HIV and TB. Achieving accurate diagnosis of TB disease is more complex in HIV patients than in subjects with normal immunity [2]. Diagnosis of pulmonary tuberculosis (TB) among human immunodeficiency virus (HIV) patients remains complex and demands easy to perform and accurate tests. The majority of performance studies of MTB/RIF have been performed in high HIV burden settings, TB diagnostic studies among HIV patients in low HIV prevalence settings such as Peru are still needed
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