Validation of San Francisco Syncope Rule

Summarized By Raviraj Patel, MD

Source: Quinn J, McDermott D, Stiell I “Prospective Validation of the San Francisco Syncope rule to Predict Patients With Serious Outcomes.” Annals of Emergency Medicine, Vol 47, No. 5: May 2006


Syncope accounts for 1-2% of all ED visits and hospital admissions and admissions may cost as high as $2 billion annually.

25% of the population will experience syncope in their lifetime

Purpose of the study was to validate San Francisco Syncope Rule using a prospective cohort.

San Francisco Syncope Rule

Positive if patient has :

  1. History of CHF
  2. Hematocrit < 30%
  3. Abnormal EKG (new changes or non-sinus rhythm)
  4. Complaint of SOB
  5. SBP < 90 mmHg at triage

The original study showed 98% sensitivity and 56% specificity in predicting adverse outcome.

Materials and Methods

Prospective cohort study at large university (UCSF) teaching hospital using EHR to track patients presenting with syncope and near syncope defined as “transient loss of consciousness with return to baseline neurologic function.”

Physicians completed Web-based data for to enroll patient with SFS Rule and asked whether rule predicted high or low risk, whether serious outcome had been identified already.

Outcome Measures

30 day follow up to determine short term outcomes requiring admission. Outcomes included death, MI, Arrhythmia, PE, CVA, SAH, significant hemorrhage or anemia requiring transfusion, hospitalization or procedural intervention treating related cause or condition to syncope.

  1. Death – confirmed in medical record, death certificate or social security death index
  2. MI – elevated trop or ekg changes w/ diagnosis of MI on discharge
  3. Arrhythmia – non-sinus rhythm (known or new) thought to be related to syncope as per treating MD
  4. PE – confirmed by V/Q scan or CT or Angiography and on discharge diagnosis, pt had to receive treatment or seen on autopsy
  5. CVA/SAH – confirmed by discharge diagnosis and chart review

Revisits for syncope or related symptoms who were admitted were considered serious outcomes

Acute intervention defined as dialysis, PPM placement, heart valve surgery, balloon-pump insertion, vasopressions, AAA surgery, surgery for splenic rupture/ectopic pregnancy, EGD for varices.

Blinded trained research RN and study investigators determined criteria for serious outcomes

Follow up completed via review of medical records, discussion with physician, patient or patients’ family, review of Social Security Death Index and a canvass of local hospitals to determine if admitted elsewhere.

Sensitivity Analysis

Required 50 outcomes for 95% Confidence Intervals width less than 10%


Table 2. Characteristics of patients presenting with syncope


Characteristic No. (%)

Age, mean (SD), y 61 (22)

Range, y 6–99

Female 427 (54%)

Admitted 469 (59%)

Patients with serious outcomes after ED visit 54 (6.8%)

Death 3

Arrhythmia 23

Myocardial infarction 11

Valvular heart disease 1

Significant hemorrhage 7

TIA/stroke 3

Sepsis 3

Admission after ED discharge 3

760 patients had 791 visits with completed forms for 767 visits.

39 patients unable to follow up but no deaths as per SSDI or local hospital canvass.

108 patients had serious outcomes within 30 days.

  1. 54 outcomes were present or diagnosed at ED visit
  2. 54 occurred within 30 days after ED visit
    1. 51/54 were admitted at ED visit
    2. 53 had data forms completed

Rule 98% Sensitive and 56% specific for serious outcomes.

1 patient the rule failed was 54 yo DM male with negative ACS w/u however found to have carotid and vertebral artery disease and subsequent stenting as thought syncope was 2/2 TIA


Single hospital where used composite serious outcome as determined by consensus of experts.

Rule should be used as risk stratifier in conjunction with thorough evaluation. Does not account for social factors, further necessary testing as outpatient.

Requires implementation study to determine true benefits.


Implementation to risk stratify could save millions of dollars as approximately 50% of syncope patients admitted undergo further specific testing leaving many syncope patients with unclear etiology.

Admitted patients length of stay normally limited to 1-2 days with only 16% receiving testing beyond simple monitoring.

Found 1 year outcomes difficult to justify need for emergency hospitalization as used in prior studies. In addition,  chose not to use Age as hard guideline as has been shown to be poor predictor of 30-day serious outcomes in ED patients with unknown syncope.

CHESS mnemonic makes easy to remember

Authors believe that absolute admission rates can decrease by 10% in low risk group with implementation of the rule.

Post-Test Here


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