Expressions and diagnostic value of interleukin-31 in tuberculous pleural effusion

Objective To analyze the expression of interleukin (IL)-31 in tuberculous pleural effusion, and to evaluate its diagnostic value of tuberculous effusion. Methods Seventy-one patients with pleural effusion were enrolled, including 40 cases of tuberculous pleural effusion and 31 cases of malignant pleural effusion. Luminex method was applied to detect the IL-31 expression in pleural effusion. IL-31 levels were compared using non-parametric Mann-Whitney U test, and the receiver operator characteristic (ROC) curve was used to elvaluate the diagnostic value of IL-31. Results IL-31 expression in tuberculous pleural effusion was significantly higher than that in malignant pleural effusion with statistical significance (529.4 ng/L vs 13.8 ng/L, U=62, P<0.01). Based on the level of IL-31 expression, area under the ROC curve was 0.95 with the optimum cut-off value of 67.5 ng/L. Thus, the sensitivity and specificity of IL-31≥67.5 ng/L for diagnosis of tuberculous pleurisy were 82.5% (95%CI: 73.3%-94.2%) and 100.0% (95%CI: 91.4%-100.0%), respectively. Conclusion IL-31 is highly sensitive and specific for the diagnosis of tuberculous pleural effusion, which favors the differentiation of tuberculosis from malignance. Key words: Interleukin-31; Pleural effusion, malignant; Tuberculosis, pleural; Differential diagnosis