Diagnostic accuracy of interleukin 27 for tuberculous pleural effusion: two prospective studies and one meta-analysis

Background Accurate differentiating diagnosis is essential for choosing treatment for exudative pleural effusions. Objective To establish the diagnostic accuracy of interleukin 27 for tuberculous pleural effusion (TPE). Methods First, the concentrations of pleural interleukin 27, interferon-gamma and adenosine deaminase were compared between 51 patients with TPE and 103 with non-TPEs (Beijing cohort), and their diagnostic values were evaluated. These were further verified in another independent population (Wuhan cohort, n=120). In the second part of the study, we performed a meta-analysis. Results With a cut-off value of 591.4 ng/L in the Beijing cohort, the area under the curve, sensitivity, specificity, positive predictive value and negative predictive value of interleukin 27 to diagnose TPE were 0.983 (95% CI 0.947 to 0.997), 96.1% (86.5% to 99.5%), 99.0% (94.7% to 100%), 98.0 (89.4 to 99.9) and 98.1 (93.3 to 99.8), respectively. Excellent diagnostic accuracy of interleukin 27 was also found in the Wuhan cohort and was further confirmed in the meta-analysis. The diagnostic performance of interleukin 27 was comparable to that of interferon-gamma and was more accurate than that of adenosine deaminase. Since the post-test probability of a negative result was always <0.1%, a negative test was considered to exclude TPE in all tuberculosis prevalence settings. Conclusions Interleukin 27 can be used to diagnose TPE in a high prevalence setting, and a negative result can also be reliably used to rule out TPE in all prevalence settings.