A Comparative Study to Evaluate C-Reactive Protein and Procalcitonin as a Marker of Bacterial Infection in Patients with Acute Exacerbation of Chronic Obstructive Pulmonary Disease

Abstract

Introduction: Exacerbations of chronic obstructive pulmonary
disease (COPD) can be precipitated by several factors. The
most common causes appear to be respiratory tract infections.
The overuse of antibiotics is common and accelerates
the development of drug resistance and hospital-acquired
infections. In some recent studies, both C-reactive proteins
(CRP), as well as procalcitonin (PCT) levels, have been shown
to be useful in differentiating bacterial etiology of exacerbations
and thus helping in guiding the treatment as well as in prediction
of outcome. This study aims to evaluate the sensitivity and
specificity of CRP and procalcitonin as a marker of bacterial
infection in patients with acute exacerbation of COPD.
Material and Methods: A total of 50 patients from patients of
COPD with acute exacerbation attending/admitted to pulmonary
OPD/IPD were included in the study, excluding those below
40 years old or presenting with acute breathlessness due
to comorbid conditions. Demographic information, relevant
clinical data, and lab investigations were recorded from all
patients, including C-reactive protein and procalcitonin, on
admission following which the patients have started antibiotics
as per guidelines. Reassessment of S. procalcitonin and CRP
was done on the 3rd and 7th day of hospitalization. Receiveroperating
characteristic (ROC) curve was applied to compare
sensitivity and specificity.
Results: Sputum culture was found positive in 27 (54%)
patients. At all the three intervals, CRP levels had ROC area
under curve (ROC AUC) values above 0.70. The area under
curve value was maximum on day 3. For PCT, the area under
curve values was > 0.8 on day 1 and 3, but on day 7 this value
was only 0.624. On evaluating the correlation between S.
C-reactive protein and PCT levels, a mild positive and significant
correlation was observed at day 1 and 7 intervals, whereas
on day 3 a moderate positive and significant correlation was
observed between the two markers.
Conclusion: The CRP is a good marker when tested early and
late, while PCT is better when tested early.