Usefulness of Serum C-reactive Protein in the Management of Adult Community-acquired Pneumonia

C-Reactive protein (CRP) is widely used as a marker of infection, but there is insufficient evidence as to its usefulness in patients with community-acquired pneumonia (CAP). In the present study, we investigated the clinical usefulness of CRP in a retrospective study of 242 patients aged 14 years who were hospitalized with CAP. Patients were classified into three groups according to the number of days between disease onset and the initial measurement of CRP as follows: Group 1, 0-1 day; Group 2, 2-4 days; Group 3, 5 days. Patients in Groups 2 and 3, who had more severe pneumonia, had higher CRP levels. Over time, CRP levels decreased in the responders in Groups 2 and 3; specifically, in Group 2, median CRP levels on Days 0, 3, and 7 were 9.85, 5.33, and 0.81mg/dL, respectively, compared with 9.99, 4.29, and 0.70mg/dL, respectively, in Group 3. In patients not responding to initial treatment, median CRP levels increased from Day 0 to Day 3 (4.32 vs. 11.70mg/dL, respectively). In all non-responders, CRP levels on Day 3 were>50% of levels on Day 0. In conclusion, when measured approximately 48 h after disease onset, CRP is useful for evaluating the severity of pneumonia and predicting the response to treatment. A good clinical outcome is likely when CRP levels on Day 3 are 50% of those on admission