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.