We sought to evaluate the usefulness of biomarkers—procalcitonin (PCT), C-reactive protein (CRP) and proadrenomedullin (pro-ADM)—combined with prognostic scales (PSI, CURB-65 and SCAP score) for identifying adverse outcomes in patients with community-acquired pneumonia (CAP) attending at an Emergency Department (ED).

Prospective observational study in a teaching hospital among patients with CAP. In addition to collecting data for the prognostic scales, samples were taken at the ED for assessing PCT, CRP and pro-ADM levels. We compared the prognostic accuracy of these biomarkers with severity scores to predict pneumonia related complications, using the area under the receiver operating characteristics curves (AUC), which evaluates how well the model discriminate between patients who had a pneumonia related complication or not.

A total of 491 patients with CAP were enrolled, 256 being admitted to the hospital and 235 treated as outpatients. Admitted patients had higher biomarker levels than outpatients (p < 0.001). The SCAP score and pro-ADM level had the best AUCs for predicting pneumonia related complications (0.83 and 0.84, respectively). Considering SCAP score plus pro-ADM level, the AUC increased significantly to 0.88. SCAP score class 0 or 1 with a pro-ADM level <0.5 ng/mL was the best indicator for selecting patients for outpatient care.

A new risk score combining SCAP score with pro-ADM level is useful to classify severity risk in CAP patients and hence supporting decision-making on hospital admission.