Protein C May Distinguish Sepsis From Pneumonia

CHICAGO — Protein C levels may be useful as an early biomarker to distinguish patients with sepsis from those with pneumonia.

In a retrospective chart review of 1,047 protein C tests performed in 980 patients, average protein C activity levels were significantly less in sepsis patients at 59.2% than in pneumonia patients at 108.9%, principal investigator Scott Gutovitz and his colleagues at Orlando (Fla.) Health reported in a poster presentation at the annual meeting of the American College of Emergency Physicians.

The researchers conducted the retrospective review over a 14-month period at an eight-hospital health care system. They identified 32 samples from patients with sepsis and 34 samples from patients with pneumonia and no clinical evidence of sepsis. Charts were excluded if the measurement was obtained before the sepsis/pneumonia event or more than 10 days after the event.

Protein C levels were significantly lower in the sepsis group (mean age 38 years) than in the pneumonia group (mean age 51.5 years) in the 0- to 12-hour interval after diagnosis (49% vs. 91%), 12- to 24-hour interval (61% vs. 109.3%), 24- to 48-hour interval (64% vs. 117.2%), and 48- to 240-hour interval (61.5% vs. 115%).

Although the number of patients in each subgroup was small and thus resulted in fairly large confidence intervals, the finding is fairly consistent over time, Dr. Gutovitz said in an interview.

Complicating a correct pneumonia diagnosis is the fact that pneumonia is a clinical and radiologic diagnosis, whereas sepsis is defined as the presence or presumed presence of an infection plus at least two systemic inflammatory response syndrome (SIRS) criteria.

Protein C is known to be lower in patients with sepsis, but its levels in nonseptic patients with pneumonia have not previously been quantified, he said. In a previous study, SIRS criteria were not useful predictors for progression to severe sepsis in community-acquired pneumonia (Chest 2006;129:968-78).