Diagnostic accuracy of biomarkers of oxidative stress in parapneumonic pleural effusions

Abstract

The imbalance between oxidants and antioxidants is referred to as oxidative stress and has been associated with various respiratory disorders. The aim of this study was the assessment of 8-isoprostane (8-iso-PGF(2α)) and Cu/Zn superoxide dismutase (Cu/Zn SOD) in exudative pleural effusions in order to examine the diagnostic accuracy of these markers in the differentiation between complicated and uncomplicated parapneumonic effusions. The study included 214 consecutive patients with pleural effusions [68 parapneumonic (31 uncomplicated parapneumonic, 20 complicated parapneumonic, 17 empyemas), 24 tuberculous, 88 malignant and 34 transudates]. 8-Isoprostane and Cu/Zn SOD were determined by ELISA in pleural fluid and serum. Parapneumonic effusions were characterized by higher pleural fluid 8-isoprostane levels compared to transudative, malignant and tuberculous effusions. Pleural fluid Cu/Zn SOD levels were lower in transudates, while serum levels were higher in transudative compared to all exudative pleural effusions. Both pleural fluid 8-isoprostane and Cu/Zn SOD were higher in complicated parapneumonic effusions and empyemas compared to uncomplicated parapneumonic effusions. Pleural fluid 8-isoprostane was the most accurate test to differentiate between complicated and uncomplicated parapneumonic pleural effusions with a sensitivity of 100% and a specificity of 58·1% at a cut-off point of 35·1 (AUC = 0·848). Pleural fluid 8-isoprostane and Cu/Zn SOD may provide useful information for the differentiation between uncomplicated and complicated parapneumonic effusions and empyemas.