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.