Residual pleural thickening is related to vascular endothelial growth factor levels in parapneumonic pleural effusions

Many patients with pneumonia develop pleural effusions. Pleural fluid vascular endothelial growth factor (VEGF) levels are known to be elevated in complicated parapneumonic effusion and seem to play a major role in the fibrotic process in the pleura.

To test whether VEGF levels in pleural effusions of infectious origin correlate with the residual pleural thickening.

VEGF levels were measured in the pleural fluid of 45 patients with pleural effusion of infectious origin. Patients were reassessed 3 months after hospital discharge and residual pleural thickening (RPT) was recorded using a simple chest radiograph.

Pleural fluid VEGF was higher in empyemas compared to simple parapneumonic and complicated parapneumonic effusions. RPT was higher in patients with empyemas compared to simple parapneumonic effusions. Patients with RPT >2 mm had higher pleural fluid LDH and pleural fluid to serum LDH ratio, lower glucose and pH and higher VEGF levels. However, patients with RPT ≥10 mm differed only in pleural fluid VEGF levels. Pleural fluid VEGF levels correlated to RPT and to pleural fluid pH. VEGF presented moderate performance for the prediction of RPT 3 months after hospital discharge. Its performance was comparable to that of pleural fluid glucose and pH for the development of a radiologically significant RPT >2 mm, whereas it was the only statistically significant predictor of a clinically significant RPT ≥10 mm.

VEGF levels are elevated in complicated parapneumonic effusions and empyemas compared to simple parapneumonic effusions and are a significant predictor for the development of clinically significant RPT.