A comparative study on the value of Xpert MTB/RIF and T-SPOT.TB tests in the diagnosis of bone and joint tuberculosis

Abstract

Background: We evaluated the application value of Xpert MTB/RIF and T-SPOT.TB in the diagnosis of bone and joint tuberculosis.

Methods: One hundred two patients with suspected bone and joint tuberculosis (BJTB) were admitted to Zhengzhou Orthopaedics Hospital, Henan, China from April 2018 to February 2019. The Xpert MTB/RIF and T-SPOT.TB tests were performed using pus specimens and peripheral blood, respectively. The diagnostic performance of Xpert MTB/RIF and T-SPOT.TB tests was evaluated on the basis of the composite reference standard (CRS).

Result: A Total of 73 suspected BJTB were enrolled and categorized, including 12 confirmed BJTB, 27 probable BJTB and 34 non-BJTB. When CRS was used as the reference, the specificity, PPV and NLR values of the Xpert MTB/RIF assay were significantly higher than those of the T-SPOT.TB assay (97.1% vs. 82.4%, p < 0.05; 96.7% vs. 85.4%, p < 0.05; 0.26 vs. 0.12, p < 0.05). However, the sensitivity, NPV and PLR values of the T-SPOT. TB assay were significantly higher than those of the Xpert MTB/RIF assay (89.7% vs. 74.4%, p < 0.05; 87.5% vs. 76.7%, p < 0.05; 5.08 vs. 2.52, p < 0.05). The AUCs from Xpert MTB/RIF and T-SPOT. TB tests were 0.857 and 0.860, respectively. However, the difference was not statistically significant. The Xpert MTB/RIF and T-SPOT. TB tests demonstrated medium concordance in diagnosing BJTB.

Conclusion: The sensitivity of T-SPOT.TB test combined with the specificity of Xpert MTB/RIF not only shorten the time of diagnosis but also improve the accuracy of diagnosis of BJTB and reduce the misdiagnosis rate. Therefore, they are useful for early diagnosis of BJTB.

Keywords: Bone and joint tuberculosis; Diagnosis; T-SPOT.TB; Xpert MTB/RIF.