[Clinical value of surfactant protein-A in 
exudate pleural effusion]

To evaluate the clinical value of surfactant protein-A (SP-A) in exudate pleural effusion (EPE).
 Methods: This clinical study was prospective, observational and cross-sectional. Two hundred and fifteen patients with pleural effusion were divided into the transudate pleural effusions (TPE) group and the EPE group. TPE patients served as the control group. The concentrations of pleural effusions SP-A (SP-Apl) and serum SP-A (SP-Ase) were measured by ELISA, and receiver operator characteristic (ROC) curve and multivarate Cox analysis of SP-A was analysed for its clinical value.
 Results: SP-Apl concentrations in the EPE group were significantly higher than that in the TPE group [(189.8±43.4) ng/mL vs (22.3±5.1) ng/mL, P<0.01]; SP-Ase concentrations in the EPE group were higher than that in the TPE group [(78.9±11.3) ng/mL vs (25.8±12.4) ng/mL, P<0.05]; SP-Apl concentrations were significantly higher than the concentrations of SP-Ase in the EPE group (P<0.01). In EPE group, SP-Apl and SP-Ase concentration in the patients with primary lung adenocarcinomas were the highest. The cut off value of SP-Apl concentrations was more than 484.5 ng/mL, yielding a 85.4% sensitivity and 95.2% specificity for diagnosing primary lung adenocarcinomas, with an area under the curve (AUC) of 0.943 (95% CI 0.852 to 0.934, P<0.01); when SP-Ase concentration was more than 84.2 ng/mL, it yielded a 76.4% sensitivity and 94.3% specificity for diagnosing primary lung adenocarcinomas, with an AUC of 0.910 (95% CI 0.921 to 0.953, P<0.01).
 Conclusion: While SP-Apl concentration is more than 484.5 ng/mL and/or SP-Ase concentration is more than 84.2 ng/mL, it may be helpful for the diagnosis of primary lung adenocarcinomas with the usage of pleural effusion.