The value of apolipoprotein E in distinguishing benign and malignant unilateral pleural effusions.

Pleural effusion (PE) remains insurmountable challenge and public health problem, requiring novel noninvasive biomarkers for accurate diagnosis. The aim of this study was to assess the clinical significance of apolipoprotein E (Apo-E) in PE, in order to determine its potential use as a diagnostic biomarker for malignant PE (MPE). PE samples were obtained from 127 patients and the etiology of PE was determined by multiple diagnostic techniques. Apo-E levels were then measured in the pleural fluid samples. 58 PE patients were diagnosed with tumors, while 69 were tumor-free. Apo-E levels in MPE patients were significantly higher than those with benign PE (BPE) (P < .05). An Apo-E cut-off of 69.96 ng/mL yielded sensitivity and specificity of 79.31% and 73.91% respectively for MPE detection. The area under the curve for Apo-E was 0.793 (95% confidence interval: 0.712 to 0.860), which was smaller than that of carcinoembryonic antigen (CEA) (Z = 2.081, P<.05). In addition, the combination of Apo-E and CEA detection yielded a higher sensitivity of 87.90% and specificity of 95.65% in diagnosing MPE. In conclusion, Apo-E levels in PE may be a potential biomarker for the detection of MPE. The combined detection of Apo-E and CEA could improve the diagnostic sensitivity and specificity for MPE. These findings provide a simple and convenient method for clinical screening and detection of PE.