Clinical Evaluation Of T-SPOT.TB Test For The Diagnosis Of Tuberculosis

Objective To evaluate the usefulness of T-SPOT.TB test for the diagnosis of tuberculosis (TB) in the First Affiliated Hospital, College of Medicine, Zhejiang University (FAHZU).Methods We conducted a retrospective analysis of1181patients who had a T-SPOT.TB test in FAHZU from Nov2010to May2012. The factors influence diagnostic value of T-SPOT.TB test was analyzed.Results The sensitivity and specificity of T-SPOT.TB test were83.2%and81.6%. The positive predictive value and negative predictive value of test were64.5%and92.3%respectively in FAHZU. The positive rate of test in pulmonary TB group was higher than extrapulmonary TB group (P=0.002), but lower if it had a treatment of anti-TB chemotherapy longer than2weeks in half a year (P=0.011). The positive rate of T-SPOT.TB test in immune suppressive group and Diabetes group was equal to normal group (P=1.000and0.661). Blood sample hemolysis group had a lower positive rate than normal group (P=0.001). There was statistical difference between T-SPOT.TB test and PPD test in clinical TB diagnosis (P=0.009). The cut-off of test can be6or5.Conclusions The extrapulmonary TB infection have a negative influence on the result of T-SPOT.TB test, anti-TB chemotherapy before the T-SPOT.TB test cause false negative result. Blood sample hemolysis may reduce the positive rate. Higher sensitivity of T-SPOT.TB than PPD test for the diagnosis of TB infection.