Development and validation of a modified quick SOFA scale for risk assessment in sepsis syndrome

Abstract

Sepsis is a severe clinical syndrome owing to its high mortality. Quick Sequential Organ Failure Assessment (qSOFA) score has been proposed for the prediction of fatal outcomes in sepsis syndrome in emergency departments. Due to the low predictive performance of the qSOFA score, we propose a modification to the score by adding age. We conducted a multicenter, retrospective cohort study among regional referral centers from various regions of the country. Participants recruited data of patients admitted to emergency departments and obtained a diagnosis of sepsis syndrome. Crude in-hospital mortality was the primary endpoint. A generalized mixed-effects model with random intercepts produced estimates for adverse outcomes. Model-based recursive partitioning demonstrated the effects and thresholds of significant covariates. Scores were internally validated. The H measure compared performances of scores. A total of 580 patients from 22 centers were included for further analysis. Stages of sepsis, age, time to antibiotics, and administration of carbapenem for empirical treatment were entered the final model. Among these, severe sepsis (OR, 4.40; CIs, 2.35-8.21), septic shock (OR, 8.78; CIs, 4.37-17.66), age (OR, 1.03; CIs, 1.02-1.05) and time to antibiotics (OR, 1.05; CIs, 1.01-1.10) were significantly associated with fatal outcomes. A decision tree demonstrated the thresholds for age. We modified the quick Sequential Organ Failure Assessment (mod-qSOFA) score by adding age (> 50 years old = one point) and compared this to the conventional score. H-measures for qSOFA and mod-qSOFA were found to be 0.11 and 0.14, respectively, whereas AUCs of both scores were 0.64. We propose the use of the modified qSOFA score for early risk assessment among sepsis patients for improved triage and management of this fatal syndrome.

Fig 1. The model-based decision tree for fatal outcomes among patients with sepsis syndrome.

The fatal outcome is first partitioned among stages of sepsis (SOS). Sepsis node partitioned by time to antibiotics, followed by age. Age partitioned severe sepsis and septic shock nodes. Terminal nodes displayed as bar plots giving the percentages of fatal outcomes in the node. Of notice was the patients under 50 years old who received antibiotics within three hours were all survived.

Fig 2. Comparative performances of scores.

(A) H measure at different severity ratios. Severity ratio is the ratio of the cost of false positive over the cost of false negative predictions.; (B) Table of H measure, AUC, true positive (TP), false positive (FP), true negative (TN) and false negative (FN) predictions of scores.