Application value of GeneXpert MTB/RIF, TB-IGRA and traditional histopathology in the diagnosis of spinal tuberculosis

English Keywords:Application value of Gene MTB/RIF, TB-IGRA and traditional histopathology in the diagnosis of spinal tuberculosis

English Abstract:

  【Abstract】 Objectives: To evaluate the value of traditional histopathology, Gene Xpert MTB/RIF (Xpert) and interferon-gamma release assay for mycobacterium tuberculosis(TB-IGRA) in the diagnosis of spinal tuberculosis. Methods: The data of 131 patients diagnosed as "spinal tuberculosis" in our hospital from November 2017 to June 2020 were analyzed retrospectively. Among the 131 patients, 79(60.3％) were males and 52(39.7％) were females; aged 18 to 90 years (50.0±18.0 years old). The locations of the disease: 39 cases of thoracic vertebrae, 57 cases of lumbar vertebrae, 12 cases of lumbosacral vertebrae, 11 cases of thoracolumbar segment, 7 cases of cervical vertebrae and 5 cases of sacral vertebrae. All patients were tested for TB-IGRA before operation, and then the lesion tissues were obtained by puncture or operation. Histopathological examination and Xpert test were carried out respectively, and the positive and negative rates were calculated. Histopathological diagnosis was divided into four categories: category Ⅰ was confirmed tuberculosis, category Ⅱ was inclined to tuberculosis,category Ⅲ was suspected tuberculosis and category Ⅳ was undiagnosed tuberculosis. Categories Ⅰ and Ⅱ supported the diagnosis of spinal tuberculosis, while Ⅲ and Ⅳ didn′t support. With histopathological diagnosis as the gold standard, the sensitivity and specificity of Xpert and TB-IGRA examination were obtained and the Kappa value was calculated to evaluate their consistency. The positive rates of single detection and combined detection were compared respectively. The receiver operating characteristic(ROC) curve of Xpert and TB-IGRA was drawn and the area under curve(AUC) was calculated to evaluate the value of Xpert and TB-IGRA. Results: Among the 131 patients, 85 were diagnosed with confirmed TB by histopathology(64.9%, 95%CI: 56.6%-73.2%), 46 were undiagnosed TB by histopathology (35.1%, 95%CI: 26.8%-43.4%), Xpert was positive in 79 cases (60.3%, 95%CI: 51.0%-68.1%), and negative in 52 cases(39.7%, 95%CI: 31.9%-49%), rpoB mutations were found in 6 cases(4.6%, 95%CI 0.95%-8.20%), and TB-IGRA was positive in 99 cases(75.6%, 95%CI: 68.1%-83.0%), negative in 32 cases(24.4%, 95%CI 17.0%-31.9%). 89 cases of spinal tuberculosis(67.9%, 95%CI: 59.02%-75.32%) were diagnosed by histopathological examination and Xpert, 42 cases of undiagnosed tuberculosis(32.1%, 95%CI: 24.68%-40.98%). 107 cases of spinal tuberculosis(81.7%, 95%CI 74.97%-88.39%) were diagnosed by histopathological examination and TB-IGRA, 24 cases of undiagnosed tuberculosis (18.3%, 95%CI 11.61%-25.03%). The sensitivity and specificity of Xpert were 87.1% (74/85) and 91.3%(42/46); the sensitivity and specificity of TB-IGRA were 90.6%(77/85) and 52.2%(24/46). The positive rate of histopathology combined with Xpert test in the diagnosis of spinal tuberculosis was 67.9%(89/131); the positive rate of histopathology combined with TB-IGRA test in the diagnosis of spinal tuberculosis was 81.7%(107/131); the positive rate of the three examination combined diagnosis of spinal tuberculosis was 82.4%(108/131). Based on the clinical diagnostic criteria, the positive rate of TB-IGRA combined with pathological examination was higher than that of pathological examination(χ2=9.435, P=0.002), the positive rate of TB-IGRA combined with pathological examination was higher than that of pathological examination(χ2=9.855, P=0.002), and also higher than that of Xpert combined with pathological examination(χ2=16.681, P<0.001). The Kappa value of spinal tuberculosis diagnosed by histopathological examination and Xpert was 0.76(95%CI 0.631-0.873), that of histopathological examination and TB-IGRA was 0.46(95%CI 0.295-0.616). The AUC of spinal tuberculosis diagnosed by Xpert was 0.892, and that of TB-IGRA was 0.751. Conclusions: TB-IGRA has high sensitivity, Xpert has high specificity, and rifampicin resistant mutations can be found; the combined Histopathological examination of them has high application value in the diagnosis of spinal tuberculosis.