Value Of Interferon-gamma Release Assay In Pulmonary Tuberculosis

Objective:To investigate the diagnostic value of interferon-gamma release assay(IGRA)in different types of pulmonary tuberculosis(TB)such as active tuberculosis(active TB),non-active tuberculosis(non-active TB),sputum smear-positive tuberculosis and smear-negative tuberculosis.Methods:IGRA was performed in 1449 hospitalized patients in our hospital and the People’s Hospital of Chongqing from January 1,2015 to December 31,2016.The sensitivity and specificity of IGRA for diagnosis of TB was evaluated,specifically in patients with TB,active TB,non-active TB,and other pulmonary diseases,as well as TB in special population.Results:The sensitivity of IGRA in patients with TB(84.4%)was significantly different from the patients with other pulmonary diseases(P < 0.05);however no significant difference was seen in the sensitivity between active TB(85.6%)and non-active TB(79.7%,P>0.05).In sputum smear-positive and smear-negative TBs,the sensitivity of the sensitivity of IGRA was respective 85.1% and 86.6%,which was not statistically different(P>0.05).There were 25 cases tested as sputum smear-positive but IGRA negative.Among them,80%(20 cases)were Mycobacterium tuberculosis and 20%(5 cases)were non-tuberculosis mycobacterium.Four cases of pregnant women with TB were all IGRA positive(100%).Conclusion:(1)active TB and non-active TB cannot be differentially diagnosed by IGRA alone,other examinations should be combined to improve the diagnostic accuracy.(2)Patient with sputum smear-positive but IGRA negative may possibly be infected by non-tuberculosis mycobacterium.Mycobacterium strains should be further identified.(3)In special population such as pregnant women who had no TB history,IGRA-positive result is helpful for the diagnosis of active TB.