Utility of C-reactive protein in assessing the disease severity and complications of community-acquired pneumonia

Abstract

Previous studies on the usefulness of C-reactive protein (CRP) in patients with community-acquired pneumonia (CAP) have yielded somewhat inconsistent results. Our aim was to assess the value of CRP in estimating the severity and complications of CAP. CRP levels during the first 5 days of hospitalization were measured in 384 adult patients with CAP, and the data were evaluated using comprehensive statistical analyses. Significantly higher CRP levels on admission were detected in Pneumonia Severity Index (PSI) classes III-V than in classes I and II (p <0.001). An increment of 50 mg/L CRP on admission was associated with a 1.22-fold odds for a patient to be in PSI classes III-V as compared with classes I and II (OR 1.22, 95% CI 1.11-1.34; p <0.001). CRP levels were significantly higher in bacteraemic pneumonia than in non-bacteraemic pneumonia (p <0.001). An increment of 50 mg/L CRP was associated with a 1.67-fold odds for a patient to be bacteraemic (OR 1.67, 95% CI 1.46-1.92; p <0.001). CRP levels >100 mg/L on day 4 after the admission were significantly associated with complications (p <0.01). There was a trend for an association between the level of CRP on admission and the time to reach clinical stability (p <0.01). In conclusion, CRP may be valuable for revealing the development of complications in CAP. It may also be useful to assess the disease severity, thus being complementary to the assessment of the PSI. In our patients, high CRP levels were associated with a failure to reach clinical stability.