Diagnostic and Prognostic Value of Procalcitonin in Community-Acquired Pneumonia

Introduction: The value of measuring procalcitonin (PCT) in patients with community-acquired pneumonia (CAP) is unclear. The aim of this study was to determine the value of PCT as a marker for microbial etiology and a predictor of outcome in CAP patients. Methods: A single-center observational study was conducted with CAP patients. On admission, their leukocyte count, serum C-reactive protein level, and serum PCT level were determined, and microbiological tests were performed. Patients were classified into 4 groups according to the A-DROP scoring system, which assesses the severity of CAP. Results: A total of 102 patients were enrolled. The pathogen was identified in 60 patients, and 31 patients had streptococcal pneumonia. The PCT levels were significantly higher in those patients with pneumococcal pneumonia than in those patients with other bacterial pneumonias (P < 0.0001). Multivariate regression analysis revealed that high PCT levels were associated with a pneumococcal etiology [odds ratio, 1.68; 95% confidence interval (CI): 1.02-2.81; P = 0.04] after adjustment for disease severity and demographic factors. The PCT levels were correlated with the A-DROP score (r = 0.49; P < 0.0001). The area under the curve for predicting mortality was highest for the A-DROP score (0.97; 95% CI: 0.92-0.99), followed by the area under the curve for PCT (0.82; 95% CI: 0.74-0.89) and C-reactive protein (0.77; 95% CI: 0.67-0.84). Conclusions: High PCT levels indicate that pneumococcal pneumonia and PCT levels depend on the severity of pneumonia. PCT measurements may provide important diagnostic and prognostic information for patients with CAP.