Application of T-SPOT.TB in connective tissue disease combined with tuberculosis / 中华检验医学杂志

ABSTRACT

Objective To investigate the diagnostic value of the T-SPOT.TB in connective tissue disease(CTD) combined with tuberculosis.Methods This is a case-control study.Forty-four patients with CTD combined with tuberculosis were enrolled from Xiangya Hospital of Central South University from September 2011 to July 2012.Another forty-four CTD patients without tuberculosis were evaluated as a control group.The diagnostic value of T-SPOT.TB and risk factors of the false negative results by T-SPOT.TB were analyzed.Results The sensitivity of T-SPOT.TB (70.5％,31/44) was significantly higher than that of TST(27.3％,12/44) for CTD combined with tuberculosis patients (x2 =16.42,P ＜ 0.001).The specificity of T-SPOT.TB and TST were 93.2％ (41/44) and 88.6％ (39/44),respectively.There was no significant difference between the specificity (x2 =0.14,P =0.711).The positive predictive value of T-SPOT.TB was 91.2％ (31/34).The negative predictive value was 75.9％ (41/54).Youden's index was 0.64,and the positive likelihood ratio was 10.3.All the index were higher than that of TST (0.16 and 2.4).While the negative likelihood ratio which was 0.32 was lower than that of TST (0.82).When spot forming cell frequencies of T-SPOT.TB of PBMC was set to 38SFCs/106 PBMC,it had the best cut-off value.Age,use of glucocorticoids or immunosuppressant therapy,lymphocytopenia and hypoalbuminemia were not associated with false negative T-SPOT.TB assay.Conclusion The T-SPOT.TB assay is much more useful than TST for diagnosing CTD combined with tuberculosis.