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Updated: Sep 14, 2025

Diagnosing Pulmonary Tuberculosis with the Xpert MTB/RIF Test
Published on: April 9, 2012
Sensitivity and specificity of Xpert MTB/RIF for extrapulmonary non-spinal osteoarticular tuberculosis
Sanika Rapole1, Siddharth Aiyer1, Warid Altaf1
1Sancheti Institute for Orthopaedics & Rehabilitation, Pune, India.
Background:
Conventional diagnostics for Osteoarticular Tuberculosis (OATB) are slow and prone to inaccuracy due to low bacterial load, delaying treatment. Xpert MTB/RIF is WHO-recommended for TB cases, but there is a dearth of literature for non-spinal OATB.
Methods:
In a 4-year study (Sept 2016-Feb 2020), non-spinal osteoarticular infections were retrospectively analyzed. Xpert MTB/RIF sensitivity and specificity were evaluated against tuberculosis defined by histology and culture against patients having culture-isolated pyogenic infections as a reference standard for negative tuberculosis.
Results:
Among 26 OATB patients, 2 were culture-positive, 4 histopathology-positive, and 2 positive for both. The overall results of Xpert MTB/RIF were 86.9% negative predictive value (NPV), 100% specificity, 100% positive predictive value (PPV), & 65.3% sensitivity.
Conclusion:
The sensitivity & specificity of Xpert MTB/RIF in non-spinal OATB are lower, despite its effectiveness in diagnosing pulmonary tuberculosis.
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