Derivation and Validation of Predictive Factors for Clinical Deterioration after Admission in Emergency Department Patients Presenting with Abnormal Vital Signs Without Shock

Introduction: Strategies to identify high-risk emergency department (ED) patients often use markedly abnormal vital signs and serum lactate levels. Risk stratifying such patients without using the presence of shock is challenging. The objective of the study is to identify independent predictors of in-hospital adverse outcomes in ED patients with abnormal vital signs or lactate levels, but who are not in shock. Methods: We performed a prospective observational study of patients with abnormal vital signs or lactate level defined as heart rate >= 130 beats/min, respiratory rate >= 24 breaths/min, shock index >= 1, systolic blood pressure < 90mm/Hg, or lactate >= 4mmole/L. We excluded patients with isolated atrial tachycardia, seizure, intoxication, psychiatric agitation, or tachycardia due to pain (ie: extremity fracture). The primary outcome was deterioration, defined as development of acute renal failure (creatinine 2x baseline), nonelective intubation, vasopressor requirement, or mortality. Independent predictors of deterioration after hospitalization were determined using logistic regression. Results: Of 1,152 consecutive patients identified with abnormal vital signs or lactate level, 620 were excluded, leaving 532 for analysis. Of these, 53/532 (9.9 +/- 2.5%) deteriorated after hospital admission. Independent predictors of in-hospital deterioration were: lactate > 4.0mmol/L (OR 5.1, 95% CI [2.1-12.2]), age >= 80 yrs (OR 1.9, CI [1.0-3.7]), bicarbonate < 21mEq/L (OR 2.5, CI [1.3-4.9]), and initial HR >= 130 (OR 3.1, CI [1.5-6.1]). Conclusion: Patients exhibiting abnormal vital signs or elevated lactate levels without shock had significant rates of deterioration after hospitalization. ED clinical data predicted patients who suffered adverse outcomes with reasonable reliability.