Comparison of diagnostic accuracy of QuantiFERON‐TB Gold Plus and T‐SPOT.TB in the diagnosis of active tuberculosis in febrile patients

OBJECTIVE: This study aimed to compare the accuracy of QuantiFERON‐TB Gold Plus (QFT‐Plus) and T‐SPOT.TB for diagnosing active tuberculosis (ATB) in febrile patients, to explore influencing factors of positive results and to verify the potential value of QFT‐Plus in the identification of ATB and latent tuberculosis infection (LTBI). METHODS: A total of 240 febrile patients with ATB (n = 80) and non‐ATB (n = 160) were recruited to assess the accuracy of QFT‐Plus and T‐SPOT.TB for diagnosing ATB. Multivariable logistic regression was used to analyze the influencing factors of positive results. RESULTS: The proportion of indeterminate results (ITRS) in QFT‐Plus and T‐SPOT.TB were 3.3% and 0%, respectively. The consistency between the results of the QFT‐Plus and T‐SPOT.TB was substantial. The area under the receiver operating characteristic curve (AUROC) of the QFT‐Plus and T‐SPOT.TB for diagnosing ATB was 0.792 and 0.849 (p = 0.070), respectively. The sensitivity of differentiating ATB from non‐ATB was 92.2% in QFT‐Plus versus 95.0% in T‐SPOT.TB. The influencing factors of T‐SPOT.TB positive result were male (odds ratio (OR) = 2.33, 95% confidence interval (CI) 1.27–4.26, p = 0.006), evidence of previous TB (OR 11.36, 95% CI 4.62–27.94, p < 0.001), while male (OR = 3.17, 95% CI 1.73–5.84, p < 0.001), evidence of previous TB (OR = 7.58, 95% CI 3.60–15.98, p <0.001), and use of immunosuppressant (OR = 0.49, 95% CI 0.260.94, p = 0.030) were influencing factors for QFT‐Plus positive result. There was no significant difference in QFT‐Plus in differentiating ATB from LTBI in febrile patients. CONCLUSION: There was no significant difference between QFT‐Plus and T‐SPOT.TB for diagnosing ATB in febrile patients. QFT‐Plus is prone to ITRS. The influencing factors including males, evidence of the previous TB, and use of immunosuppressant should be considered when interpreting positive results.