Multicenter Emergency Department Validation of the Canadian Syncope Risk Score

Abstract

IMPORTANCEThe 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 PARTICIPANTSThis 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 RELEVANCEThe 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.

External validation of the Canadian Syncope Risk Score for patients presenting with undifferentiated syncope to the emergency department

“…The diagnostic accuracy of the CSRS was modest with a lower sensitivity of 71.4% (95% CI 30.3–94.9%) for a threshold score of −1 or higher (low to very‐high‐risk) compared with the derivation study (97.7% [95% CI 93.5–99.5%]) and multi‐centre validation study (97.8% [95% CI 93.8–99.6%]). Specificity was 50.4% and similar to the derivation study (45.1% [95% CI 43.5–46.8%]) and multi‐centre Canadian study (44.3% [95% CI 42.7–45.9%]) 24,25 . Sensitivity was maintained, but with a higher specificity of 72.8% (95% CI 67.1–77.9%) for a threshold of 1 or higher (medium to very‐high‐risk) reflecting a hypothetical cut‐off decision for discharge of very‐low and low‐risk patients which was similar to previous studies 24,25 .…”

“…Specificity was 50.4% and similar to the derivation study (45.1% [95% CI 43.5–46.8%]) and multi‐centre Canadian study (44.3% [95% CI 42.7–45.9%]) 24,25 . Sensitivity was maintained, but with a higher specificity of 72.8% (95% CI 67.1–77.9%) for a threshold of 1 or higher (medium to very‐high‐risk) reflecting a hypothetical cut‐off decision for discharge of very‐low and low‐risk patients which was similar to previous studies 24,25 . The low number of 30‐day SAE in the small study sample influenced the robustness of the sensitivity estimates with resultant wide CIs.…”

“…The distribution of 30‐day SAEs differed from the derivation and multi‐centre validation study which may have contributed to differences in sensitivity performance of the CSRS 24,25 . In our study, over half of the 30‐day SAEs were classed as other serious conditions which has a broad and subjective interpretation.…”

“…In their derivation study, the sensitivity of the rule was 97.7% (95% confidence interval [CI] 93.5–99.5%) for a threshold score of −1 or higher 24 . A recent multi‐centre validation study by the same authors confirmed the robustness of their decision rule which demonstrated high accuracy and reproducibility with patients in the very‐low to low‐risk category having a likelihood of 30‐day SAE in the order of 0.2 and 0.7% respectively 25 . This represents a cohort of low risk patients where hospital admission could be avoided without further significant risk of harm 14 .…”

Machine Learning and Syncope Management in the ED: The Future Is Coming

“…More recently, the Canadian Syncope Risk Score was developed and externally validated in a large population of Canadian patients, showing good discrimination and calibration for 30-day risk of serious adverse events after disposition from the ED. However, it needs to be validated in different settings before recommending its implementation in clinical practice [ 81 , 82 ].…”