Table of Contents
Journal of Biomarkers
Volume 2016, Article ID 2198745, 5 pages
Research Article

The Diagnostic Value of Serum C-Reactive Protein for Identifying Pneumonia in Hospitalized Patients with Acute Respiratory Symptoms

Department of Internal Medicine, Arnau de Vilanova University Hospital, Biomedical Research Institute of Lleida Foundation Dr. Pifarré (IRBLleida), 25198 Lleida, Spain

Received 10 May 2016; Accepted 25 July 2016

Academic Editor: Mark Duncan

Copyright © 2016 Agustín Ruiz-González et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Background. The clinical diagnosis of pneumonia is sometimes difficult since chest radiographs are often indeterminate. In this study, we aimed to assess whether serum C-reactive protein (CRP) could assist in identifying patients with pneumonia. Methods. For one winter, all consecutive patients with acute respiratory symptoms admitted to the emergency ward of a single center were prospectively enrolled. In addition to chest radiographs, basic laboratory tests, and microbiology, serum levels of CRP were measured at entry. Results. A total of 923 (62.3%) of 1473 patients hospitalized for acute respiratory symptoms were included. Subjects with a final diagnosis of pneumonia had higher serum CRP levels (median 187 mg/L) than those with exacerbations of chronic obstructive pulmonary disease (63 mg/L) or acute bronchitis (54 mg/L, ). CRP was accurate in identifying pneumonia (area under the curve 0.84, 95% CI 0.82–0.87). The multilevel likelihood ratio (LR) for intervals of CRP provided useful information on the posttest probability of having pneumonia. CRP intervals above 200 mg/L were associated with LR+ > 5, for which pneumonia is likely, whereas CRP intervals below 75 mg/L were associated with LR < 0.2, for which pneumonia is unlikely. Conclusion. Serum CRP may be a useful addition for diagnosing pneumonia in hospitalized patients with acute respiratory symptoms.