Original article
C-reactive protein velocity following antibiotics in patients with chronic obstructive pulmonary disease exacerbation and community acquired pneumonia

https://doi.org/10.1016/j.ejim.2009.03.008Get rights and content

Abstract

Introduction

Distinguishing community acquired pneumonia (CAP) from chronic obstructive pulmonary disease (COPD) exacerbation is a challenging task, since fever, productive cough, dyspnea, and leukocytosis are all common features of both conditions. Moreover, chest X-ray might not be sensitive enough. It is therefore quite common for physicians to prescribe unnecessary antibiotics for COPD exacerbation, leading to resistant bacteria and other related adverse affects.

Aim

To study whether CRP levels upon admission and the delta in CRP levels following initiation of antibacterial treatment, could provide an efficient tool for distinguishing CAP from COPD exacerbation.

Methods

The study group included 36 COPD exacerbation and 49 CAP patients, admitted to a single Internal Medicine department during the years 2004–2006. All patients were treated with cephalosporins and macrolides upon admission.

Results

CRP levels upon admission were significantly higher among CAP patients than among COPD exacerbation patients (111.5 ± 104.4 vs. 34.9 ± 28.6 mg/l, p < 0.0001). CRP levels on the second day of hospitalization, following antibiotic administration to all patients, made a sharp incline in 36.7% of CAP patients compared to only 5.9% of COPD exacerbation patients (p = 0.005), and remained unchanged in 61.8% of COPD patients compared to 16.3% of CAP patients (p = 0.0006).

Conclusions

CRP levels upon admission and the delta in CRP levels following initiation of antibacterial treatment could provide an efficient tool for distinguishing CAP from COPD exacerbation.

Introduction

Chronic obstructive pulmonary disease (COPD) exacerbation and community acquired pneumonia (CAP) are both life-threatening conditions; 2843 patients died of COPD and CAP complications in Israel during 2003 alone [1]. An increase in the incidence of CAP in the future is predicted due to the proliferation of resistant bacteria strains and lack of new antibiotics for CAP [2]. Hence, it is crucial to treat CAP patients with suitable antibiotics and avoid unnecessary antibiotic treatment in COPD exacerbation patients. However, it is often difficult to distinguish COPD exacerbation from CAP, since fever, productive cough, dyspnea, and leukocytosis are common features of both conditions, and COPD exacerbation patients are thus often treated with unnecessary antibiotics. In addition to this, COPD patients are inherently prone to invasive pneumonia, which a regular chest X-ray might not easily demonstrate [3]. Hence, physicians often prescribe unnecessary antibiotics to COPD patients without proof of a pulmonary infiltrate on chest X-ray. Prescribing unnecessary antibiotics to COPD exacerbation patients increases the risk for bacterial resistance, pseudo-membranous colitis and drug eruption, as well as other adverse affects [2]. Prescribing steroids to COPD exacerbation patients, on the other hand, might increase the risk for invasive pneumonia in these patients. It is therefore highly important to develop methods for distinguishing COPD exacerbation from CAP.

Elevated serum C-reactive protein (CRP) is considered a risk factor for the development of cardiovascular disease, and associated with poor cardiovascular prognosis [4]. CRP is used as a measure to distinguish bacterial infections from aseptic inflammation [5]. Though CRP levels on presentation have been used to distinguish COPD exacerbation from CAP in the past [6], its delta following antibiotics administration has never been used for this purpose. CRP levels on presentation are a useful index for patients treated in an ambulatory setting, while CRP velocity following antibiotics administration may be more useful in the hospitalized patient.

Wide-range CRP has been used in our facility on a daily basis since 2004 [7]. We have observed CRP elevations in many CAP patients the day following antibiotic administration and a lack of increase in CRP levels in COPD exacerbation patients observed at a similar interval. Since we found no reference to this observation in the relevant literature, we decided to conduct this retrospective analysis. We believe this observation is highly important, since it may prevent unnecessary antibiotic treatment in COPD exacerbation patients.

Section snippets

Study design

This was a retrospective analysis of patient charts. Data was collected with permission of the institutional Helsinki committee.

Included patients

Included were all COPD exacerbation/CAP patients hospitalized in a single Internal Medicine department between 2004 and 2006, who had their CRP levels measured on admission (before initiation of antibiotics) and the following day (after initiation of antibiotics). CAP was defined by the appearance of an infiltrate on chest X-ray (as confirmed by a radiologist),

Results

Our initial cohort included 150 patients with COPD exacerbation and CAP. Following exclusion of 64 patients whose CRP levels were measured only on admission or the following day, and after excluding 4 additional patients in whom we could not distinguish COPD exacerbation from CAP, the final cohort included 34 patients with COPD exacerbation and 49 patients with CAP. Clinical characteristics of the final cohort compared with those of the initial cohort are presented in Table 1. Apart from active

Discussion

Distinguishing COPD exacerbation from CAP is crucial, since most COPD exacerbations are due to viral infections whereas most CAP are due to bacterial infections. It is thus necessary to treat CAP patients with suitable antibiotics and to avoid unnecessary antibiotics in COPD exacerbation patients. Though CRP levels at presentation have been used to distinguish COPD exacerbation from CAP in the past [6], and though high CRP levels may indicate an infectious exacerbation in COPD patients [8], its

Study limitations

CRP levels of patients admitted to our ward during the study period were not obtained prospectively and according to any established guidelines. Physicians often did not obtain CRP levels from patients on admission or the following day, and patients whose CRP levels were obtained, were often younger, had a lower rate of active malignancy, resulting in a small and relatively young, healthy study group. In addition to this, we cannot conclude that obtaining CRP levels on admission and the

Conclusions

In this study we presented a new clinical feature of CRP: CRP velocity. It can be used to distinguish COPD exacerbation from CAP. We also demonstrated its clinical use in monitoring the inflammatory response following antibiotics administration in these conditions. Double-blind placebo-controlled longitudinal studies are warranted in order to confirm these findings. Physicians are, nonetheless, already implementing these findings in our medical center and their reports are encouraging.

Learning points

  • Distinguishing CAP from COPD exacerbation is challenging.

  • We studied whether CRP levels upon admission and following initiation of antibacterial treatment, could provide an efficient tool for distinguishing CAP from COPD exacerbation.

  • CRP levels upon admission were significantly higher among CAP patients than among COPD exacerbation patients.

  • A sharp incline in CRP levels following initiation of antibacterial treatment was more common in CAP patients, whereas no change in CRP levels was more

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