The Diagnostic Value of the Pleural Fluid C-Reactive Protein in Parapneumonic Effusions

Abstract

Purpose. The aim of this study was to evaluate the sensitivity of pleural C-reactive protein (CRP) biomarker levels in identifying parapneumonic effusions. Methods. A single-center, retrospective review of 244 patients diagnosed with pleural effusions was initiated among patients at the Rabin Medical Center, Petah Tikva, Israel, between January 2011 and December 2013. The patients were categorized into 4 groups according to their type of pleural effusion as follows: heart failure, malignant, post-lung transplantation, and parapneumonic effusion. Results. The pleural CRP levels significantly differentiated the four groups (p < 0.001) with the following means: parapneumonic effusion, 5.38 ± 4.85 mg/dL; lung transplant, 2.77 ± 2.66 mg/dL; malignancy, 1.19 ± 1.51 mg/dL; and heart failure, 0.57 ± 0.81 mg/dL. The pleural fluid CRP cut-off value for differentiating among parapneumonic effusions and the other 3 groups was 1.38 mg/dL. The sensitivity, specificity, positive predictive value, and negative predictive value were 84.2%, 71.5%, 37%, and 95%, respectively. A backward logistic regression model selected CRP as the single predictor of parapneumonic effusion (OR = 1.59, 95% CI = 1.37–1.89). Conclusions. Pleural fluid CRP levels can be used to distinguish between parapneumonic effusions and other types of exudative effusions. CRP levels < 0.64 mg/dL are likely to indicate a pleural effusion from congestive heart failure, whereas levels ≥ 1.38 mg/dL are suggestive of an infectious etiology.

The usefulness of pleural fluid presepsin, C-reactive protein, and procalcitonin in distinguishing different causes of pleural effusions

“…Furthermore, it confirms and extends the findings of previous investigations, in which pleural CRP levels were found to be higher in parapneumonic effusions than in other types of exudates. Izhakian et al [ 15 ] reported that pleural CRP levels were higher in parapneumonic effusion than in other effusion types, with a cut-off value of > 1.38 mg/dL. Pleural CRP had a low positive predicted value (37.6%) but a very high negative predicted value (96.7%), which suggests that it could be a powerful tool for excluding parapneumonic effusion as a diagnosis.…”

Diagnostic performance of C-reactive protein for parapneumonic pleural effusion: a meta-analysis

“…The studies were performed in nine countries and published from 2006 to 2017. Nine studies investigated the diagnostic performance of pleural CRP for PPE (15,16,(18)(19)(20)(21)24,27,28), and five studies used serum CRP to diagnose PPE (19,23,25,30,31). Seven assessed the potential of pleural CRP for differentiating CPPE from UPPE (14,16,17,21,22,26,29), two of which also determined the diagnostic role of serum CRP for CPPE (22,26).…”

Discrimination of Exudative Pleural Effusions Based on Pleural Adenosine Deaminase (ADA)-C-Reactive Protein (CRP) Levels, and Their Combination: An Observational Prospective Study

“…C-reactive protein (CRP) known as “acute-phase protein,” is synthesized by the liver in response to various stimuli and produced early in the inflammatory process. CRP is increased in the serum/plasma of patients with pneumonia and many studies also confirmed that increased pleural CRP (p-CRP) may present a possible biomarker for pleural infection, although with inconclusive results [ 4 , 5 , 6 ]. Additionally, high CRP levels (cut-off: 10 mg/dL) have been used as differentiator between complicated and non-complicated parapneumonic pleural effusions, with comparable AUC scores to those of widely accepted pleural pH and glucose [ 7 ].…”