Abstract:

Objective: To analyze the diagnostic value of combining T-cell spot test for tuberculosis infection (T-SPOT.TB), antibody (TB-Ab) test, erythrocyte sedimentation rate (ESR) test, and hypersensitive C-reactive protein (hs-CRP) test in detecting etiologically negative pulmonary tuberculosis(PTB). Methods: Data of 216 PTB patients who were initially treated and had negative etiological test results (etiologically negative PTB group) were collected from the Tuberculosis Clinic of the Beijing Center for Disease Prevention and Control from July 2020 to July 2022. Meanwhile 147 primary PTB patients with positive etiological test results and 455 patients with other pulmonary diseases who were admitted during the same period were classified as the etiologically positive PTB group and other lung disease group respectively. All of them were tested with T-SPOT.TB, TB-Ab, ESR, and hs-CRP to analyze the diagnostic performance of single test and combined tests with those four methods, based on clinical diagnosis. Results: The detection positive rate of T-SPOT.TB in etiologically negative PTB group was 82.4% (178/216), no statistically significant difference was observed comparing with the detection positive rate in etiologically positive PTB group (87.8% (129/147); χ²=1.917,P=0.166), but the difference was statistically significant (χ²=160.746,P=0.000), while comparing with the detection positive rate in other pulmonary disease group (28.6%, 130/455). The sensitivity, specificity, positive and negative predictive value and accuracy of T-SPOT.TB were 82.9% (178/216), 71.4% (325/455), 57.8% (178/308), 89.5% (325/363), 75.0% (503/671), respectively. While for combination of all four methods, they were 91.7% (198/216), 53.4% (243/455), 48.3% (198/410), 93.1% (243/261), 65.7% (441/671), respectively. The area under ROC curve (AUC) of T-SPOT.TB, TB-Ab, ESR and hs-CRP test were 0.764, 0.600, 0.529 and 0.515, respectively, and the AUC of combining those four tests was 0.804. Conclusion: The sensitivity, negative predictive value and accuracy of the T-SPOT.TB test for detecting etiologically negative PTB were relatively good, and the sensitivity, negative predictive value and AUC of combining four test methods were relatively high, which indicates that combining tests could improve the diagnostic efficacy for detecting etiologically negative pulmonary tuberculosis.

Key words: Tuberculosis, pulmonary, Clinical laboratory techniques, Enzyme-linked immunospot assay, C-reaction protein, Comparative study