This inconsistency might lie in different samples used for VEGF measurement, including the cerebrospinal fluid (CSF), the peripheral blood, the pleural effusion (PE), the ascites or pericardial fluid, and different conditions served as a control condition, such as apparently healthy conditions, malignancy, empyema and parapneumonic effusion (PPE), transudate effusion, etc. Here, VEGFA is linked to empyema.