by Sophie Quinn
Even though the above-mentioned decision thresholds for pleural pH or glucose are commonly used to screen for CPPE, the evidence supporting this practice comes from consensus of clinical opin-ion. In fact, the diagnostic yield of these parameters in the present study was disappointing in that 55% (12 of 22 patients) with PPE who ultimately underwent drainage exhibited pleural levels of pH and glucose > 7.20 and > 60 mg/dL, respectively. Unfortunately, the inadequate sensitivity of the preferred tests (ie, pH or glucose) contrasts with the critical decision to initiate prompt drainage when indicated. For this reason, alternative biochemical markers, such as pleural SC5b-9, myeloperoxi-dase, or TNF-а, has been proposed to aid decision making for drainage. In a pilot study, we reported sensitivity (100%), specificity (75%), and AUC (0.89) of the terminal complement complex SC5b-9 in pleural fluid for differentiating nonpurulent CPPE from UPPE when a cutoff point of 1,500 ^g/L was used. Likewise, in the study of Alegre et al, pleural myeloperoxidase at a cut point limit of 3,000 ^g/L was found to be the marker that best discriminated between these two types of PPE (sensitivity, 87.5%; specificity, 85.1%; AUC = 0.91). store4family.nl