Qingluan Yang1, Chubin Zhang1, Qiaoling Ruan2, Wei Zhang1, Haocheng Zhang1, Yang Li1, Lingyun Shao3, Wenhong Zhang4. 1. Department of Infectious Diseases, Huashan Hospital, Fudan University, Shanghai 200040, China. 2. Department of Infectious Diseases, Huashan Hospital, Fudan University, Shanghai 200040, China; National Clinical Research Center for Aging and Medicine, Huashan Hospital, Fudan University, Shanghai 200040, China. 3. Department of Infectious Diseases, Huashan Hospital, Fudan University, Shanghai 200040, China; National Clinical Research Center for Aging and Medicine, Huashan Hospital, Fudan University, Shanghai 200040, China. Electronic address: lingyun26@fudan.edu.cn. 4. Department of Infectious Diseases, Huashan Hospital, Fudan University, Shanghai 200040, China; National Clinical Research Center for Aging and Medicine, Huashan Hospital, Fudan University, Shanghai 200040, China; State Key Laboratory of Genetic Engineering, School of Life Science, Fudan University, Shanghai 200438, China; Key Laboratory of Medical Molecular Virology, (MOE/MOH) and Institutes of Biomedical Sciences, Shanghai Medical College, Fudan University, Shanghai 200032, China.
Abstract
BACKGROUND: This study aimed to determine whether increased cut-off of the T-SPOT.TB could aid in diagnosing active tuberculosis (ATB). METHODS: Patients suspected of having TB were enrolled to derive a T-SPOT.TB threshold value to help diagnose ATB, which was subsequently validated in real-world clinical practice. RESULTS: In total, 701 adult patients suspected of having tuberculosis who had undergone the T-SPOT.TB assay were included in the derivation cohort. The numbers of ESAT-6 (U = 43583, P = 0.0002) and CFP-10 (U = 41753, P < 0.0001) spot-forming cells (SFCs) significantly increased in the ATB group compared with the Latent tuberculosis infection (LTBI) group. According to receiver operating characteristic analysis, when a cut-off of 37.5 SFCs/2.5 × 105 cells was used to discriminate between ATB and LTBI, the sensitivity was 57.5% (95% confidence interval [CI] 50.7%-64.2%) and the specificity was 59.8% (95% CI 55.2%-64.2%). A threshold value of 173.5 SFCs/2.5 × 105 could be used to obtain a specificity of <90% to discriminate between ATB and LTBI. The diagnostic accuracy of higher T-SPOT.TB threshold values in the validation cohort was similar to that in the derivation cohort. CONCLUSIONS: In high-burden countries, a higher threshold value of 173.5 SFCs/2.5 × 105 may aid in ATB diagnosis in suspected tuberculosis patients.
BACKGROUND: This study aimed to determine whether increased cut-off of the T-SPOT.TB could aid in diagnosing active tuberculosis (ATB). METHODS:Patients suspected of having TB were enrolled to derive a T-SPOT.TB threshold value to help diagnose ATB, which was subsequently validated in real-world clinical practice. RESULTS: In total, 701 adult patients suspected of having tuberculosis who had undergone the T-SPOT.TB assay were included in the derivation cohort. The numbers of ESAT-6 (U = 43583, P = 0.0002) and CFP-10 (U = 41753, P < 0.0001) spot-forming cells (SFCs) significantly increased in the ATB group compared with the Latent tuberculosis infection (LTBI) group. According to receiver operating characteristic analysis, when a cut-off of 37.5 SFCs/2.5 × 105 cells was used to discriminate between ATB and LTBI, the sensitivity was 57.5% (95% confidence interval [CI] 50.7%-64.2%) and the specificity was 59.8% (95% CI 55.2%-64.2%). A threshold value of 173.5 SFCs/2.5 × 105 could be used to obtain a specificity of <90% to discriminate between ATB and LTBI. The diagnostic accuracy of higher T-SPOT.TB threshold values in the validation cohort was similar to that in the derivation cohort. CONCLUSIONS: In high-burden countries, a higher threshold value of 173.5 SFCs/2.5 × 105 may aid in ATB diagnosis in suspected tuberculosispatients.