Accuracy of interleukin-27 in diagnosing tuberculous pleural effusion: Age should be considered.

BACKGROUND: Tuberculous pleural effusion (TPE) diagnosis still faces many difficulties and challenges. Some studies have shown that pleural interleukin -27 (IL-27) had a diagnostic potential for TPE. However, their findings are not always consistent. This study aimed to investigate the diagnostic accuracy of pleural IL-27 for TPE. METHODS: We prospectively enrolled 211 patients with undiagnosed pleural effusion. Effusion Mycobacterium tuberculosis (Mtb) culture, Ziehl-Neelsen staining, biopsy, and response to antituberculosis therapy were used to define TPE. The pleural IL-27 levels were determined by enzyme-linked immunosorbent assay (ELISA). A receiver operating characteristic curve (ROC) with the area under the curve (AUC) was used to evaluate the diagnostic accuracy of IL-27 for TPE. In addition, we investigated the influence of age on the diagnostic performance of IL-27 by resampling patients with different upper age limits in the inclusion criteria. RESULTS: Among the 211 enrolled participants, 33 were TPE and 178 were non-TPE. The mean concentration of IL-27 in TPE patients was significantly higher than that of non-TPE patients. The AUC of IL-27 was 0.76 (95 %CI: 0.67-0.86). At the threshold of 500 pg/mL, the sensitivity and specificity of IL-27 were 0.26 (95 %CI: 0.20-0.33) and 0.91 (95 %CI:0.76-0.97), respectively. The AUC of IL-27 is 0.84 in patients with an upper age limit of 70. Still, it decreased to 0.76 in patients with an upper age limit of 75. CONCLUSION: Age can affect the diagnostic performance of IL-27 for TPE.