| Objective To investigate the value of the combined Mycobacterium tuberculosis-specific interferon-γ(IFN-γ)and interleukin-2(IL-2)assay(enzyme-linkedimmunoassay,ELISA)for the auxiliary diagnosis of pulmonary tuberculosis in patients with pulmonary tuberculosis and the factors influencing false negatives.Methods Case data of 421 patients with suspected pulmonary tuberculosis sent for the combined IFN-γ/IL-2 test from a 3A hospital from January 2021 to March 2022were collected.324 Patients with clearly diagnosed pulmonary tuberculosis and 78non-tuberculosis patients(control group)were included in this study,including 166patients with bacillus-negative pulmonary tuberculosis(bacillus-negative group),bacillus-positive 158 patients with pulmonary tuberculosis(bacillus-positive group),71patients with pulmonary infectious diseases,and 7 patients with lung tumors;another 11patients with unclear diagnosis and 8 patients with incomplete data were not included in the study.The results of the combined IFN-γ/IL-2 test and tuberculin purified protein derivative(PPD)skin test at the time of admission were collected to analyze the value of the combined IFN-γ/IL-2 test as an aid to the diagnosis of pulmonary tuberculosis.The 324 pulmonary tuberculosis patients were grouped according to the results of IFN-γ/IL-2 combined test,among which 59 cases had negative results(false negative group)and 265 cases had positive results(positive group),and the factors influencing the false negative of IFN-γ/IL-2 combined test were analyzed using univariate and multifactorial logistic regression.Results 1.The area under the working characteristic curve(AUC)of subjects with IFN-γ/IL-2 combined test was maximum 0.884,95%CI(0.839-0.930)in TB patients;the AUC of IL-2 single test was maximum 0.877,95%CI(0.833-0.922)in bacteriophage negative TB patients;in bacteriophage positive TB The AUC of IFN-γ/IL-2 combination test was 0.898 with 95%CI(0.851-0.944),while the AUC of PPD skin test was the lowest.2.The sensitivity of the combined IFN-γ/IL-2 test was(81.8%,78.3%,85.4%)higher than other tests in TB patients,bacillus-negative TB patients and bacillus-positive TB patients,respectively,while the specificity of IL-2single test was 87.2%higher than other tests.3.The number of false-negative combinations with diabetes mellitus in the combined IFN-γ/IL-2 test was 15 cases,positive combination and diabetes was 37 cases,the difference between the two groups was statistically significant(χ~24.705,P 0.03),the lymphocyte count(10~9/L)in the false negative group was 1.33(0.89,1.65)lower than the lymphocyte count in the positive group 1.53(1.11,2.02),the difference between the two groups was statistically significant(Z 2.659,P 0.008);4,The risk of false negatives in the combined interferon-gamma and interleukin-2 assay was 2.514 times(95%CI:1.352-4.675)higher in those with lower lymphocyte counts(<1.045×10~9/L)than in those with higher lymphocyte counts(>=1.045×10~9/L).Conclusions The combined Mycobacterium tuberculosis-specific IFN-γ/IL2 test has a high diagnostic value as an aid in the diagnosis of both bacillus-negative and bacillus-positive pulmonary tuberculosis;the use of the combined IFN-γ/IL2 test helps in the early detection and accurate diagnosis of bacillus-negative pulmonary tuberculosis.Lymphocyte count<1.045×10~9/L was an independent influencing factor for false-negative Mycobacterium tuberculosis-specific interferon-γand interleukin-2combination test in patients with pulmonary tuberculosis. |
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