Abstract
Objectives: The role of serum C-reactive protein (CRPs) and pleural fluid CRP (CRPpf) in discriminating uncomplicated parapneumonic effusion (UCPPE) from complicated parapneumonic effusion (CPPE) is yet to be validated since most of the previous studies were on small cohorts and with variable results. The role of CRPs and CRPpf gradient (CRPg) and of their ratio (CRPr) in this discrimination has not been previously reported. The study aims to assess the diagnostic efficacy of CRPs, CRPpf, CRPr, and CRPg in discriminating UCPPE from CPPE in a relatively large cohort. Methods: The study population included 146 patients with PPE, 86 with UCPPE and 60 with CPPE. Levels of CRPs and CRPpf were measured, and the CRPg and CRPr were calculated. The values are presented as mean ± SD. Results: Mean levels of CRPs, CRPpf, CRPg, and CRPr of the UCPPE group were 145.3 ± 67.6 mg/L, 58.5 ± 38.5 mg/L, 86.8 ± 37.3 mg/L, and 0.39 ± 0.11, respectively, and for the CPPE group were 302.2 ± 75.6 mg/L, 112 ± 65 mg/L, 188.3 ± 62.3 mg/L, and 0.36 ± 0.19, respectively. Levels of CRPs, CRPpf, and CRPg were significantly higher in the CPPE than in the UCPPE group (p < 0.0001). No significant difference was found between the two groups for levels of CRPr (p = 0.26). The best cut-off value calculated by the receiver operating characteristic (ROC) analysis for discriminating UCPPE from CPPE was for CRPs, 211.5 mg/L with area under the curve (AUC) = 94% and p < 0.0001, for CRPpf, 90.5 mg/L with AUC = 76.3% and p < 0.0001, and for CRPg, 142 mg/L with AUC = 91% and p < 0.0001. Conclusions: CRPs, CRPpf, and CRPg are strong markers for discrimination between UCPPE and CPPE, while CRPr has no role in this discrimination.
Highlights
Parapneumonic effusion (PPE) is an accumulation of exudative pleural fluid that occurs in association with an ipsilateral pulmonary infection, mainly pneumonia, and may accompany lung abscess and infected bronchiectasis
Analysis for discriminating uncomplicated parapneumonic effusion (UCPPE) from complicated parapneumonic effusion (CPPE) was for C-reactive protein (CRP), 211.5 mg/L with area under the curve (AUC) = 94% and p < 0.0001, for CRPpf, 90.5 mg/L with AUC = 76.3% and p < 0.0001, and for CRPpf gradient (CRPg), 142 mg/L with AUC = 91% and p < 0.0001
The results of our study demonstrate that CRPg is a very useful marker for the discrimination between UCPPE and CPPE (Table 1; Figure 3)
Summary
Parapneumonic effusion (PPE) is an accumulation of exudative pleural fluid that occurs in association with an ipsilateral pulmonary infection, mainly pneumonia, and may accompany lung abscess and infected bronchiectasis. PPEs are the most common exudative pleural effusions, and are present in 20% to 54% of patients with bacterial pneumonia [1,2]. UCPPEs are free flowing effusions, not infected, have a pH level greater than 7.2, a glucose level greater than 60 mg/dL, and lactate dehydrogenase (LDH) level less than 1000 IU/L. CPPE usually are infected, have a pH level less than 7.2, a glucose level less than 60 mg/dL, and LDH level greater than 1000 IU/L. These effusions are initially thin and serous, but become more purulent as the disease progresses. The natural course of a CPPE is to develop a single loculus or multiple loculations, and to progress to empyema when the effusion becomes thick and turbid, which represents the end stage of a Diagnostics 2020, 10, 829; doi:10.3390/diagnostics10100829 www.mdpi.com/journal/diagnostics
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