Protein C as an early biomarker to distinguish pneumonia from sepsis

Patients with pneumonia often are unrecognized as also having sepsis. We evaluated protein C, as a potential biomarker, to differentiate between patients with pneumonia and sepsis.

A retrospective chart review was performed for all protein C tests over a 14-month period (January 11, 2007, to March 10, 2008) at an 8-hospital system with 1706 total beds. Charts were screened for the discharge diagnoses of sepsis, severe sepsis, septic shock, bacteremia, and pneumonia. Protein C levels were compared between patients with sepsis and pneumonia, and at time intervals of 0 to 12 hours, 12 to 24 hours, 24 to 48 hours, and more than 48 hours after diagnosis.

One thousand forty-seven protein C levels were obtained in 980 patients. Thirty-two protein C levels met the inclusion and exclusion criteria for the sepsis group, and 34 for the pneumonia group. Overall, the mean protein C levels were significantly less in patients with sepsis at 59.2% (95% confidence interval [CI], 49.5%-68.9%) compared with patients with pneumonia at 108.9% (95% CI, 95.6%-122.3%; P < .001). In addition, levels within each of the time intervals were also significantly lower in the sepsis group.

In this study, protein C levels performed well in differentiating between patients with sepsis or pneumonia in the early period after diagnosis.