Abstract
IMPORTANCE: The management of patients with syncope in the emergency department (ED) is challenging because no robust risk tool available has been recommended for clinical use. OBJECTIVE: To validate the Canadian Syncope Risk Score (CSRS) in a new cohort of patients with syncope to determine its ability to predict 30-day serious outcomes not evident during index ED evaluation. DESIGN, SETTING, AND PARTICIPANTS: This prospective multicenter cohort study conducted at 9 EDs across Canada included patients 16 years and older who presented to EDs within 24 hours of syncope. Patients were enrolled from March 2014 to April 2018. MAIN OUTCOMES AND MEASURES: Baseline characteristics, CSRS predictors, and 30-day adjudicated serious outcomes, including arrhythmic (arrhythmias, interventions for arrhythmia, or unknown cause of death) and nonarrhythmic (myocardial infarction, structural heart disease, pulmonary embolism, or hemorrhage) serious outcomes, were collected. Calibration and discrimination characteristics for CSRS validation were calculated. RESULTS: A total of 3819 patients were included (mean [SD] age 53.9 [22.8] years; 2088 [54.7%] female), of whom 139 (3.6%) experienced 30-day serious outcomes, including 13 patients (0.3%) who died. In the validation cohort, there were no differences between the predicted and observed risk, the calibration slope was 1.0, and the area under the receiver operating characteristic curve was 0.91 (95% CI, 0.88-0.93). The empirical probability of a 30-day serious outcome during validation was 3.64% (95% CI, 3.09%-4.28%) compared with the model-predicted probability of 3.17% (95% CI, 2.66%-3.77%; P = .26). The proportion of patients with 30-day serious outcomes increased from 3 of 1631 (0.3%) in the very-low-risk group to 40 of 78 (51.3%) in the very-high-risk group (Cochran-Armitage trend test P < .001). There was a similar significant increase in the serious outcome subtypes with increasing CSRS risk category. None of the very-low-risk and low-risk patients died or experienced ventricular arrhythmia. At a threshold score of -1 (2145 of 3819 patients), the CSRS sensitivity and specificity were 97.8% (95% CI, 93.8%-99.6%) and 44.3% (95% CI, 42.7%-45.9%), respectively. CONCLUSIONS AND RELEVANCE: The CSRS was successfully validated and its use is recommended to guide ED management of patients when serious causes are not identified during index ED evaluation. Very-low-risk and low-risk patients can generally be discharged, while brief hospitalization can be considered for high-risk patients. We believe CSRS implementation has the potential to improve patient safety and health care efficiency.