The role of serum procalcitonin in the differential diagnosis of pneumonia from pulmonary edema among the patients with pulmonary infiltrates on chest radiography

The aim of this study is to evaluate the usefulness of serum procalcitonin (PCT) as a diagnostic biomarker for distinguishing pneumonia from pulmonary edema in patients presenting with pulmonary infiltrates on chest radiography. A comparative study was performed retrospectively in a university-affiliated hospital, from May, 2013 to April, 2015. Adult patients (≥18 years) who showed pulmonary infiltrates on chest radiography and had blood tests with C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), PCT, and N-terminal pro-b-type natriuretic peptide (NT-proBNP) on admission were included in the study. Clinical parameters collected on admission were compared between the case group (n = 143) with pneumonia and the control group (n = 88) with pulmonary edema alone. During the study period, a total of 1217 patients were identified. Of them, a total of 231 patients were included in analyses based on exclusion criteria. In the multivariate logistic regression analysis, PCT ≥0.25 ng/mL, ESR ≥35 mm/h, CRP ≥18 mg/L, NT-proBNP ≤200 pg/mL, underlying neurologic diseases, fever, sputum, absence of cardiomegaly, and a low Charlson comorbidity index were independently associated with pneumonia. For this model, the sensitivity, specificity, positive predictive value, and negative predictive value in distinguishing between the 2 groups were 90.2%, 79.6%, 87.8%, and 83.3%, respectively, with an area under the curve of 0.93. This study suggests that the practical use of PCT in conjunction with clinical data can be valuable in the differential diagnosis of pulmonary infiltrates and guidance for clinicians to prevent antibiotic misuse.