Matrix metalloproteinase levels in the differentiation of parapneumonic pleural effusions.

BACKGROUND Matrix metalloproteinases (MMPs) have been implicated in the escalation of fibrosis and remodeling which are central to the subsequent progression of a parapneumonic pleural effusion to empyema. OBJECTIVES The aim of this study was the assessment of MMP-2, MMP-8 and MMP-9 in parapneumonic pleural effusions in order to examine their value in the differentiation between uncomplicated and complicated parapneumonic effusions. METHODS The study included 208 consecutive patients with pleural effusions [60 parapneumonic (27 uncomplicated parapneumonic, 17 complicated parapneumonic, 16 empyemas), 24 tuberculous, 89 malignant and 35 transudates]. Concentrations of pleural fluid and serum MMP-2, MMP-8 and MMP-9 were determined by immunoassay. RESULTS Pleural fluid MMP-8 and MMP-9 levels were higher in complicated parapneumonic effusions or empyema than in uncomplicated effusions, while their serum levels were higher in complicated parapneumonic effusions. MMP-2 levels were higher in uncomplicated than in complicated parapneumonic effusions or empyema. Pleural fluid MMP-2/MMP-9 ratio was the best marker to differentiate complicated from uncomplicated parapneumonic effusions, with a sensitivity of 94.1% and a specificity of 77.8% at a cut-off point of 1.32 (AUC = 0.887). CONCLUSIONS Pleural fluid MMP-2, MMP-8 and MMP-9 may provide useful information for differentiating between uncomplicated and complicated parapneumonic effusions.