Chest
Volume 108, Issue 5, November 1995, Pages 1288-1291
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Clinical Investigations: Infection
C-Reactive Protein: A Clinical Marker in Community-Acquired Pneumonia

https://doi.org/10.1378/chest.108.5.1288Get rights and content

Study objective

To assess the range of plasma C-reactive protein (CRP) in patients presenting with community-acquired pneumonia and to compare the serial changes of this acute-phase protein with clinical outcome.

Design

Prospective hospital-based study, including separate retrospective case series.

Patients

Twenty-eight consecutive patients (mean age, 60 years) admitted to our hospital with community-acquired pneumonia were studied. Serial daily plasma samples were taken and assayed for CRP, tumor necrosis factor-α (TNF-α), and interleukin 6 (IL-6). Clinical parameters, laboratory data, and response to treatment were recorded. Four other patients considered to be antibiotic failures (three empyemas, one death) were studied separately.

Results

Two patients died. Of those who survived, mean (±SD) CRP values for days 1, 2, 3, 4, and 5 were as follows: 136±43, 96±44, 53±36, 54±43, and 44±31 mg/L. CRP levels on day 1 in patients who had received antibiotics prior to hospital admission were significantly lower than those who had not, 107±42 and 152±44 mg/L (p<0.05). CRP levels did not correlate with other laboratory parameters or with recognized predictors of mortality. A CRP value that continued to rise despite antibiotic treatment was associated with infective complications or death. Only 52% of patients had detectable TNF-α and 24% detectable IL-6 at some point during their hospital stay.

Conclusions

CRP is a sensitive marker of pneumonia. A persistently high or rising CRP level suggests antibiotic treatment failure or the development of an infective complication. These results suggest that CRP, rather than TNF-α or IL-6, may have a role as a clinical marker in pneumonia.

Section snippets

Patients

Twenty-eight consecutive patients admitted to our hospital with community-acquired pneumonia were prospectively studied. Pneumonia was defined as the presence of new shadowing on a chest radiograph in association with an appropriate clinical history and physical signs for which no other cause was found. Informed consent was obtained and the study was approved by the Tayside Ethical Committee. The average age was 60.5 years (range, 25 to 88 years), 18 were male, and 10 had preexisting lung

Results

Plasma CRP levels were elevated above 50 mg/L in all and above 100 mg/L in 75% of patients on the day of hospital admission. However, only 67% of patients had a pyrexia (axilliary temperature >37°C) and only 62% an elevated WBC count (>10×109/L) at time of presentation. With antibiotic treatment, CRP levels fell rapidly as demonstrated by the data for the first 5 days (Table 1). Missing CRP data for days 2 to 5 were due to patient discharge from hospital or loss of samples. One patient

Discussion

In our study, all patients admitted to hospital with community-acquired pneumonia had an elevated CRP level at the time of hospital admission. Although small, our study did suggest that plasma CRP level is a sensitive marker of pneumonia unlike other more commonly used clinical markers of sepsis such as body temperature and WBC count which were not elevated in a significant proportion of our pneumonia patients. This is supported by similar findings in other studies of community-acquired

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