Diagnostic Value And Influence Factors Of Peripheral Blood Interferon-gamma Release Test In Patients With Tuberculous Pleurisy

Objective:This study is to investigate the diagnostic value of Peripheral blood interferon-gamma release assay(IGRA)in patients with tuberculous pleurisy and to analyze the risk factors for IGRA results.Methods:The samples were collected from patients with exudative pleural effusion in our Department of Respiratory Medicine from January 1,2017 to December 31,2018.The results of IGRA test,relevant laboratory indicators and clinical data were analyzed by SPSS22.0 software.Results:1、The positive rate of IGRA,PPD test,pleural fluid adenosine deaminase(ADA),serum tuberculosis antibody(TB-Ab)and pleural effusion tuberculosis antibody(TB-Ab)were 91.25%,71.25%,70.00%,25.00% and 22.50% in patients with tuberculous pleural effusion,which were higher than those of non-tuberculous pleurisy group(36.00%,53.33%,14.67%,17.33% and 16.00%).among them,IGRA and pleural effusion ADA showed statistically significant difference(P<0.001),PPD test showed statistical difference(P<0.05),while serum TB-Ab and pleural effusion TB-Ab showed no statistical difference between two groups.The sensitivity and specificity of the three of the testing methods(IGRA,PPD test and pleural effusion ADA)with statistical differences were calculated and compared.The sensitivity of IGRA was 91.25%,statistically higher than that of ADA and PPD test(P<0.05).The specificity of IGRA was 64.00%,statistically lower than ADA(P<0.05).2、Age and BMI were significantly associated with false negative IGRA results(P<0.05)in patients with tuberculous pleurisy.Multivariate Logistic regression analysis showed that older age and BMI(>25)were independent risk factors for false negative IGRA.3、In patients with non-tuberculous pleurisy,univariate analysis found that history of tuberculosis,CRP,ESR,lymphocyte count,leukocyte count and neutrophil count were significantly associated with false positive IGRA results(P<0.05).Through multivariate Logistic regression analysis,only previous TB history was found to be an independent risk factor for false positive IGRA results.4、Interferon-gamma release level of the age group(18-53 years old)was higher than that of the age group(>53 years old),with statistical significance.All patients were divided into three groups according to BMI:BMI(<18.5),BMI(18.5-25)and BMI(>25).Statistical results showed that there was a statistical difference in the release level of interferon-gamma among the three groups(H<0.05).Further pairwise comparison showed that interferon-gamma release level of BMI(>25)group was lower than that of BMI(18.5-25)group(P<0.05).The statistical results showed that interferon-gamma release level of the group with previous TB history was higher than that of the group without previous TB history(P<0.05).Conclusion:IGRA has relatively high sensitivity and specificity in diagnosis.Older age,BMI(>25),and Previous TB history were independent risk factors for IGRA results.For the elderly or obese patients with suspected tuberculosis,the possibility of false negative should be considered.The possibility of false positives should be considered when Patients have a history of tuberculosis.