External validation of the San Francisco Syncope Rule in the Australian context

The San Francisco Syncope Rule (SFSR) aims to identify patients with syncope who are at risk for short-term serious adverse outcomes. It has been reported to have high sensitivity and the potential to decrease admission rates. The aim of this study was to validate the SFSR in the Australasian setting.

Our prospective, observational cohort study identified patients with syncope using emergency department (ED) databases. Data, including demographics, the presence of SFSR predictors and ED disposition, were collected either during ED stay or by explicit medical record review. Patients were followed up after 7 days for defined serious outcomes (i.e., death, myocardial infarction, arrhythmia, pulmonary embolism, stroke, subarachnoid hemorrhage, significant hemorrhage or unplanned ED re-presentation). We analyzed sensitivity, specificity, and positive and negative predictive values. We compared the results with current physician-based clinical practice.

We studied 89 patients with a median age of 74 years. Of them, 42% were male and the admission rate was 39%. Ten patients (11%) suffered a serious event. The SFSR was 90% sensitive (95% confidence interval [CI] 60%-98%) and 57% specific (95% CI 46%-67%) for predicting patients with a defined serious adverse event. The SFSR also categorized 48% of patients as "high risk." If the SFSR had been strictly applied, the admission rate would have increased by 9% and 1 serious adverse event would have been missed.

The SFSR demonstrated 90% sensitivity in this validation study. Strict application of the SFSR would have increased hospital admissions but would not have identified all adverse outcomes. In our setting, clinician judgement performed as well as the syncope rule, with a baseline admission rate of 36%.