Key Point

About half of patients hospitalized with community-acquired pneumonia develop severe sepsis.

PITTSBURGH—Many patients develop severe sepsis before ICU admission, so there probably is not nearly as much information on the early course of severe sepsis as there could be. In particular, it is not even clear how frequently community-acquired pneumonia (CAP), a common reason for ICU admission, progresses to severe sepsis and which factors predict such progression.

Dremsizov and colleagues have therefore performed a retrospective study of the onset and timing of severe sepsis in patients who were hospitalized for CAP.1 The study’s other objectives were to assess the ability of systemic inflammatory response syndrome (SIRS) criteria and the pneumonia severity index (PSI) to predict severe sepsis.

"We demonstrated that the presence of SIRS criteria measured as early as the patient’s presentation to the emergency department are poorly predictive of the development of severe sepsis, septic shock, and death in pneumonia patients," related the authors. "However, the PSI was associated with subsequent development of severe sepsis although it had a weak predictive discrimination power."

Severe sepsis is common in CAP, occurring in about half of hospitalized CAP patients. "Outside of the critical care world, a lot of people believe that we have mastered pneumonia," Gilles Clermont, MD, one of the authors, told Pulmonary Reviews. "But the truth is that a lot of people still die from it," he stressed. Dr. Clermont is an Associate Professor in the Department of Critical Care Medicine at the University of Pittsburgh.

The authors analyzed data for 1,339 patients who had been enrolled in the Pneumonia Patient Outcomes Research Team study. The patients were 18 or older and had clinical and radiographic evidence of pneumonia.

Of the patients, 34.1% presented with severe sepsis; 2% were in septic shock at that time. Of the patients who did not present with severe sepsis, 20.6% developed severe sepsis later in their hospital stay.

Information on SIRS was available for 686 patients. Of this group, 82% met the accepted definition of SIRS on the first day of hospitalization, and 94% met the definition at some point during their hospitalization.

SIRS at presentation did not increase the odds of subsequent severe sepsis, septic shock, or death. Furthermore, the discriminative ability of SIRS to predict those outcomes was poor, as shown by an area under the receiver operating characteristic curve of less than 0.5 even when a more stringent SIRS definition (the presence of at least three criteria) was used. Although the PSI significantly predicted severe sepsis, an area under the curve of 0.63 indicated that the discriminative ability of the index was modest.

—Timothy Begany

Reference
1. Dremsizov T, Clermont G, Kellum JA, et al. Severe sepsis in community-acquired pneumonia: when does it happen, and do systemic inflammatory response syndrome criteria help predict course? Chest. 2006;129:968-978.

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