Comparison of the diagnostic accuracy of interleukin-27 and adenosine deaminase for tuberculous pleural effusion: A systematic review and meta-analysis with head-to-head design

Background Interleukin-27 (IL-27) in the pleural fluid has gained significant attention as a diagnostic biomarker for tuberculous pleural effusion (TPE); however, considerable variability exists across available studies. This systematic review and meta-analysis aimed to determine the diagnostic accuracy of IL-27 in identifying TPE. In addition, we also compared the diagnostic accuracy of IL-27 and adenosine deaminase (ADA) with a head-to-head meta-analysis. Methods We searched the PubMed and Web of Science databases to identify diagnostic test accuracy studies evaluating the accuracy of IL-27 for diagnosing TPE. The last search date was September 2025. We extracted data from the eligible studies and constructed a two-by-two table with true positives (TP), false positives (FP), true negatives (FN), and false negatives (FN). The QUADAS-2 tool was used to assess the quality of eligible studies. A bivariate model was applied to pool sensitivity and specificity, and a summary receiver operating characteristic (sROC) curve with the area under the curve (AUC) was generated to estimate the overall diagnostic accuracy of IL-27 and ADA. A Deeks funnel plot asymmetry test was used to evaluate publication bias. Results Nine studies encompassing ten cohorts were included, involving 1573 patients (429 with TPE and 1144 with non-TPE). The reported AUCs for IL-27 ranged from approximately 0.73 to 0.99 across eligible studies. The pooled sensitivity and specificity were 0.94 (95% CI, 0.83-0.98) and 0.96 (95% CI, 0.89-0.98), respectively. The AUC for sROC was 0.99 (95% CI, 0.97-0.99). The pooled positive likelihood ratio was 21.97 (95% CI, 7.95-60.69), the negative likelihood ratio was 0.07 (95% CI, 0.02-0.18), and the diagnostic odds ratio (DOR) was 329 (95% CI, 72-1506). Significant heterogeneity was observed in both sensitivity (I 2 ≈ 96%) and specificity (I 2 ≈ 97%). No significant publication bias was detected. Eight cohorts simultaneously assessed the diagnostic performance of ADA, and a head-to-head meta-analysis indicated that IL-27 exhibits diagnostic accuracy comparable to ADA. Several primary studies had methodological limitations related to threshold selection, sample size, and the implementation of the reference standard. Conclusions IL-27 is a promising diagnostic marker for TPE, and its diagnostic accuracy is comparable to that of ADA. IL-27 should be used as a complementary diagnostic marker to ADA for TPE.