Discussing: Quinn et al. Annals of Emergency Medicine. Prospective Validation of the San Francisco Syncope Rule to Predict Patients With Serious Outcomes
1. This 2006 prospective cohort trial aimed to validate a clinical rule to help risk stratify patients presenting to the ER with syncope in relation to short term outcomes. The rule was validated to have a sensitivity of 98% in preventing serious outcomes after syncope within 30 days.
2. The San Francisco Syncope rule is positive if the patient has a chief complaint of “shortness of breath”, a medical history of CHF, a presenting SBP <90mm Hg, a hematocrit <30%, or an abnormal ECG result (any non-sinus rhythm or new changes).
Approximately 25% of the general population will have an episode of syncope in their lifetime. Patients with syncope account for 1-2% of all Emergency Department visits and hospital admissions. Patients admitted for syncope, however, have been shown to receive little to no further diagnostic care, nor do they often receive a firm diagnosis concerning the cause of their syncope. Given this, the authors’ purpose was to validate the decision rule in a prospective cohort of consecutive ED patients by determining whether it can predict short-term serious outcomes.
Syncope was defined as “transient loss of consciousness with return to baseline neurologic function,” and patients presenting with acute syncope or pre-syncope were screened for the study. When a clinician had finished working up the selected patient, a short Web-based questionnaire was completed to evaluate for aspects of the history, ECG, vitals or lab results that pertain to the decision rule. In this trial, the decision rule was 98% sensitive and 56% specific to predict a serious outcome within 30 days. If applied in the study cohort, this clinical rule may have decreased syncope admissions by 24%.
Overall this study was well done, and helps to risk stratify patients with syncope. The authors defined “serious outcomes” (see below) as this was their primary outcome measure. This metric was well described and well laid out in the methodology.
Quinn and his colleagues performed a prospective cohort study at one large academic medical center, using an EMR to track potential patients presenting with a complaint of syncope. Patients were excluded if they had trauma or drug-related loss of consciousness, or presented with a definite seizure. Anyone who was not back to neurologic baseline was excluded from the study. Once the clinical provider completed a workup on a patient, that person was enrolled via a web-based data form. The clinical provider filled out the patient questionnaire that included the decision rule criteria: whether the patient had a chief complaint of “shortness of breath,” a medical history of CHF, a presenting SBP < 90 mm Hg, a hematocrit < 30%, or an abnormal ECG result (any non-sinus rhythm or new changes).
Outcomes for purpose of validation were completed at 30 days after the index ED visit. Short term serious outcomes were described as: myocardial infarction, arrhythmia, pulmonary embolism, stroke, subarachnoid hemorrhage, significant hemorrhage or anemia requiring transfusion, a procedural intervention to treat a related cause of syncope, or any condition causing or likely to cause a return ED visit AND hospitalization for a related event. Each of these outcome measures were well defined in the paper.
During the study period 760 patients had 791 ER visits for syncope with an average age of 61yrs, and 54% were women. Of the 791 patients, 767 of them had forms completed to be enrolled and follow up was achieved in 752 patients (95%). Of the visits, 108 patients had defined serious outcomes within 30 days and half of these were recognized in the ER. The most common cause of serious outcome was cardiac arrhythmia, which occurred in 23 patients
Level of Evidence:
ACEP Clinical Policy Committee Level IA
Benjamin C. Sun, Benjamin. Risk prediction for patients with syncope. Annals of Emergency Medicine, Volume 44, Issue 4, October 2004, Pages 422-423
Quinn JV, Stiell IG, McDermott DA, Sellers KL, Kohn MA, Wells GA. Derivation of the San Francisco Syncope Rule to predict patients with short-term serious outcomes. Annals of Emergency Medicine. 2004 Feb;43(2):224-32.
Quinn J, McDermott D, Stiell I, Kohn M, Wells G. Prospective Validation of the San Francisco Syncope Rule to Predict Patients With Serious Outcomes. Annals of Emergency Medicine. 2006;47:448-454.