The CSRS applies to adults (≥16 years) presenting within 24 hours of true syncope to the emergency department, after initial assessment and ECG, when no serious cause has already been identified.

Evidence & context

The derivation study included 4,030 adults at six Canadian academic emergency departments, with 3.6% experiencing adjudicated 30-day serious adverse events after ED disposition.
Included patients 16 years and older presenting within 24 hours of syncope. Excluded non-syncopal loss of consciousness (e.g. seizure, prolonged loss of consciousness >5 minutes), major trauma, intoxication, language barrier, and patients with a serious outcome already identified during the index ED visit.
The composite 30-day outcome combined death, serious arrhythmias or arrhythmia interventions, myocardial infarction, structural heart disease, pulmonary embolism, major haemorrhage and other conditions requiring acute treatment.
Internal derivation performance was strong, with an optimism-corrected C-statistic around 0.87 and shrinkage-adjusted expected risk from about 0.4% at a score of −3 to more than 80% at a score of 11.
The 2020 validation included 3,819 patients across nine EDs and showed similar event rates (3.6% 30-day serious outcomes) and excellent discrimination (area under the ROC curve about 0.91). Very low and low risk groups had ≤1% serious outcomes and no deaths or ventricular arrhythmias.
The BASEL IX cohort included 2,283 ED patients in eight countries and reported good external performance (AUC around 0.85) and low 30-day event rates (~1%) in CSRS-defined low-risk patients, with CSRS outperforming the OESIL score for identifying low risk. Much of the predictive power was driven by the treating clinician’s final diagnostic impression (vasovagal vs cardiac vs other syncope).

CSRS risk category	Score range	Observed 30-day serious outcomes (2020 validation)
Very low	−3 to −2	0.2% (3 of 1,631)
Low	−1 to 0	0.7% (9 of 1,254)
Medium	1 to 3	8.0% (55 of 687)
High	4 to 5	19.2% (32 of 167)
Very high	6 to 11	51.3% (40 of 78)

The CSRS is intended as decision support to identify ED syncope patients at very low short-term risk who may be suitable for discharge, and those at higher risk who are likely to benefit from monitored care and further investigation. It should be interpreted alongside age, comorbidities, recurrent events, ECG findings, social supports and local syncope or telemetry pathways rather than used as a stand-alone admission rule.

Canadian Syncope Risk Score