C-reactive protein levels of pleural fluid of parapneumonic effusions and its role in prognosis

The purpose of this study was to evaluate levels of C-reactive protein (CRPpf), glucose (Gpf) and lactic dehydrogenase (LDH) of pleural effusions in patients with empyema (E) (n=18), complicated parapneumonic effusions (CPPE) (n=27) and uncomplicated parapneumonic effusions (UPPEs) (n=26). The control group (n=38) was comprised of patients with malignant effusions. We determined the correlation with the values of CRPpf with LDHpf and Gpf, as well as the presence of PPE complications, which determine if there is a relationship between the values of CRPpf in research groups and PPE complications. Data were analyzed by ANOVA, Mann-Whitney U-test and Spearman’s correlation analysis. The levels of CRPpf in patients with E were 76.44±30.55, in patients with CPPE 46.42±22.1, in patients with UPPE 23.56±19.38 and lower in the malignant groups 17.27±12.9. The area under the curve for distinguishing CPPE from E was 0.882±0.044 with 95% CI for CRP and sensitivity 0.667; specificity 0.962. As for the discrimination of CPPE vs. E, it was CRP≥65.5. The relationship between levels of CRPpf and pleural adhesions in patients with PPE was not found. We conclude that CRPpf levels can help in the diagnosis of PPE, but cannot predict long-term complications.