| Objectives:To investigate the sensitivity of T-SPOT.TB assay for detection of tuberculosis and the risk factors for negative T-SPOT. TB results in patients with tuberculosis.Methods:The research was conducted by a method of retrospective case-control analysis study. We collected 36 cases of pulmonary tuberculosis (PTB) and 35 cases of tuberculous pleural effusion (TPE) from Qilu Hospital, Shandong University during December 2014 to February 2016. The diagnosis was made according to the Diagnostic Criteria for Pulmonary Tuberculosis (2008) and PUMC Respirology, respectively. The individual information, disease history and laboratory examination of the patients were investigated, all patients underwent valid T-SPOT.TB tests. Basic clinical characteristics and laboratory findings were compared and analyzed between the positive and negative T-SPOT.TB groups of tuberculosis patients. All the data was analyzed by SPSS 18.0 statistic software.Results:1、 There were 36 patients with PTB in our research. The range of their age was 21 to 80 years old,18 of them were males, with the mean age (55.4±17.7).35 cases were included in TPE group. The range of their age was 23 to 83 years old,26 of them were males, with the mean age (50.3±1 5.9).2、36 cases were included in PTB group. Among the PTB patients, the T-SPOT.TB test of 32 patients were identified as postive results, with the sensitivity of 88.9%.35 patients were diagnosed with TPE,24 cases (68.6%) among the TPE patients were with negative T-SPOT.TB test results. Compared with the percentage of PTB patients with positive results, the rate of patients with positive results in TPE group was significantly higher (P=0.036).3、Comparisons of basal characteristics and clinical laboratory findings for patients with false-negative and true-positive T-SPOT.TB results were performed. Univariate analysis showed that older age (P=0.035), male cases (P=0.027), longer duration of symptoms before hospitalization (>one month, P=0.005) and higher serum y-Glutamyl transpeptidase/albumin (GGT/ALB) level (P=0.009) were significantly correlated with the negative T-SPOT.TB results in tuberculosis patients. Multivariate analysis showed that increased age (odds radio (OR) 0.94,95% confidence interval (CI) 0.89-0.995), a longer period of illness before hospitalization (>one month, OR 48.47,95% CI 3.64-646.41), and TPE (OR 5.79,95% CI 1.03-32.38) were independent risk factors for false-negative T-SPOT.TB results in TB patients.4、The sensitivity of T-SPOT.TB assay in tuberculosis patients was negative related with age:the sensitivity of T-SPOT.TB assay of 20-40 years old、40-60 years old and more than 60 years old were 94.7%、77.3% and 69.0% respectively. The relationship between sensitivity of T-SPOT.TB assay and periods of illness before hospitalization was showed that the sensitivity of T-SPOT.TB assay was 76.2% in periods of illness before hospitalization less than 0.5 month group,96.4% in periods of illness before hospitalization more than 0.5 and less than one month group, and 59.1% in more than one month.5、We further investigated the relationship between IFN-y production (the number of SFCs/2.5*10^5 PBMCs) in the T-SPOT. TB test and the affected factors identified. Patients with age over 60 years old had significantly lower level of IFN-y production than those with age less than 60 years old (P=0.045). Significantly lower level of IFN-y production was also detected in patients with longer periods of illness before hospitalization (>one month), compared to the patients who had been ill for more than 0.5 month but less than one month (P=0.002). Patients with TPE had significantly lower level of IFN-y production than those with PTB (P=0.012). There were no significantly relationship between IFN-γ production and the gender (P=0.082) or serum GGT/ALB level (P=0.097).Conclusion:1、The sensitivity of T-SPOT.TB assay in patients with PTB was 88.9%. The sensitivity of T-SPOT.TB assay in patients with TPE was 68.6%. The sensitivity of T-SPOT.TB assay in patients with PTB was prominently higher than that in the TPE group.2、Older age, longer duration of symptoms before hospital admission, and TPE were the independent risk factors of the negative T-SPOT.TB results in tuberculosis patients, which decreased the sensitivity of T-SPOT.TB test. |
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