An Emergency Department Validation of the SEP-3 Sepsis and Septic Shock Definitions and Comparison With 1992 Consensus Definitions

Abstract

Study objective: The Third International Consensus Definitions Task Force (SEP-3) proposed revised criteria defining sepsis and septic shock. We seek to evaluate the performance of the SEP-3 definitions for prediction of inhospital mortality in an emergency department (ED) population and compare the performance of the SEP-3 definitions to that of the previous definitions.

Methods: This was a secondary analysis of 3 prospectively collected, observational cohorts of infected ED subjects aged 18 years or older. The primary outcome was all-cause inhospital mortality. In accordance with the SEP-3 definitions, we calculated test characteristics of sepsis (quick Sequential Organ Failure Assessment [qSOFA] score ≥2) and septic shock (vasopressor dependence plus lactate level >2.0 mmol/L) for mortality and compared them to the original 1992 consensus definitions.

Results: We identified 7,754 ED patients with suspected infection overall; 117 had no documented mental status evaluation, leaving 7,637 patients included in the analysis. The mortality rate for the overall population was 4.4% (95% confidence interval [CI] 3.9% to 4.9%). The mortality rate for patients with qSOFA score greater than or equal to 2 was 14.2% (95% CI 12.2% to 16.2%), with a sensitivity of 52% (95% CI 46% to 57%) and specificity of 86% (95% CI 85% to 87%) to predict mortality. The original systemic inflammatory response syndrome-based 1992 consensus sepsis definition had a 6.8% (95% CI 6.0% to 7.7%) mortality rate, sensitivity of 83% (95% CI 79% to 87%), and specificity of 50% (95% CI 49% to 51%). The SEP-3 septic shock mortality was 23% (95% CI 16% to 30%), with a sensitivity of 12% (95% CI 11% to 13%) and specificity of 98.4% (95% CI 98.1% to 98.7%). The original 1992 septic shock definition had a 22% (95% CI 17% to 27%) mortality rate, sensitivity of 23% (95% CI 18% to 28%), and specificity of 96.6% (95% CI 96.2% to 97.0%).

Conclusion: Both the new SEP-3 and original sepsis definitions stratify ED patients at risk for mortality, albeit with differing performances. In terms of mortality prediction, the SEP-3 definitions had improved specificity, but at the cost of sensitivity. Use of either approach requires a clearly intended target: more sensitivity versus specificity.

Figure 1

STROBE guidelines flowchart demonstrating the cohorts used and the number of patients in each that met criteria for each definition.

Figure 2

Proportional demonstration of the incidence of SIRS-based and qSOFA-based sepsis definitions, as well as the overlap with mortality among all ED patient with infection. Percentages in white demonstrate the proportion of each definition and mortality among the 6750 patients between Cohorts 1 and 2. Percentages in black boxes denote the proportion of total patients with each sepsis definition combination, with and without mortality. Of patients who died, 8/276 (2.9%) were identified by qSOFA alone, 101/276 (36.5%) by SIRS alone, 128/276 (46.4%) by both criteria, and 39/276 (14.2%) did not meet either criteria.

Figure 3

Visual demonstration of sensitivity (top) and specificity (bottom) for both SIRS-based, qSOFA-based, and severe sepsis definitions. qSOFA detected 21% fewer patients with infection who died during hospitalization compared to SIRS.