Sensitivity and specificity of Xpert MTB/RIF for extrapulmonary non-spinal osteoarticular tuberculosis.

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.