Epidemiology of sepsis syndrome in 8 academic medical centers

Abstract

Context: Sepsis syndrome is a leading cause of mortality in hospitalized patients. However, few studies have described the epidemiology of sepsis syndrome in a hospitalwide population.

Objective: To describe the epidemiology of sepsis syndrome in the tertiary care hospital setting.

Design: Prospective, multi-institutional, observational study including 5-month follow-up.

Setting: Eight academic tertiary care centers.

Methods: Each center monitored a weighted random sample of intensive care unit (ICU) patients, non-ICU patients who had blood cultures drawn, and all patients who received a novel therapeutic agent or who died in an emergency department or ICU. Sepsis syndrome was defined as the presence of either a positive blood culture or the combination of fever, tachypnea, tachycardia, clinically suspected infection, and any 1 of 7 confirmatory criteria. Estimates of total cases expected annually were extrapolated from the number of cases, the period of observation, and the sampling fraction.

Results: From January 4, 1993, to April 2, 1994, 12759 patients were monitored and 1342 episodes of sepsis syndrome were documented. The extrapolated, weighted estimate of hospitalwide incidence (mean+/-95% confidence limit) of sepsis syndrome was 2.0+/-0.16 cases per 100 admissions, or 2.8+/-0.17 per 1000 patient-days. The unadjusted attack rate for sepsis syndrome between individual centers differed by as much as 3-fold, but after adjustment for institutional differences in organ transplant populations, variation from the expected number of cases was reduced to 2-fold and was not statistically significant overall. Patients in ICUs accounted for 59% of total extrapolated cases, non-ICU patients with positive blood cultures for 11%, and non-ICU patients with negative blood cultures for 30%. Septic shock was present at onset of sepsis syndrome in 25% of patients. Bloodstream infection was documented in 28%, with gram-positive organisms being the most frequent isolates. Mortality was 34% at 28 days and 45% at 5 months.

Conclusions: Sepsis syndrome is common in academic hospitals, although the overall rates vary considerably with the patient population. A substantial fraction of cases occur outside ICUs. An understanding of the hospitalwide epidemiology of sepsis syndrome is vital for rational planning and treatment of hospitalized patients with sepsis syndrome, especially as new and expensive therapeutic agents become available.