EBQ:San Francisco Syncope Rule

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Complete Journal Club Article
Quinn J. et al.. "Prospective validation of the San Francisco Syncope Rule to predict patients with serious outcomes". Ann Emerg Med. 2006. 31(26):2992-6.
PubMed Full text PDF

Clinical Question

Can the San Francisco Syncope Rule be used in clinical practice to risk stratify patients presenting with syncope?

Conclusion

  • The San Francisco Syncope Rule demonstrated to be highly sensitive (98% sensitivity, 95% CI 89-100%) but not very specific (56%, 95% CI 52-60%) for predicting serious outcomes.

Major Points

Criteria (CHESS Pneumonic)[1]

The rule is positive if any of the above apply to the patient.

Study Design

  • A prospective cohort study
  • N =: 760 patients had 791 visits for syncope (1.2% of all ED visits)
  • Consecutive patients with syncope or near syncope presenting to an emergency department of a large, urban teaching hospital were identified and enrolled from July 15, 2002 to August 31, 2004
  • Physicians prospectively applied the San Francisco Syncope Rule
    • Patient follow up performed to determine if the patient suffered a predefined serious outcome within 30 days of their ED visit
    • Physicians completed a short Web-based form and enrolled patients after their assessment
    • Study investigators reviewed all data forms in order to ensure the correct interpretation of the rule
  • 30 day follow-up completed after patients' index ED visit to determine short-term outcomes that would require admission
    • Short-term serious outcomes defined as:
      • Death
      • Myocardial Infarction
        • Any elevation of troponin or ECG change with an accompanying diagnosis of myocardial infarction on D/C and confirmed by the cardiology service or primary physician
      • Arrhythmia
      • Pulmonary Embolism
        • Needed to have received treatment for the pulmonary embolism or had it confirmed on autopsy
      • Stoke
      • Subarachnoid Hemorrhage
      • Significant Hemorrhage or Anemia Requiring Transfusion
      • Procedural intervention to treat a related cause of syncope or any condition causing or likely to cause a return ED visit
      • Hospitalization for a related event

Population

Patient Demographics

  • 364 men, 427 females
  • Mean age: 61
  • 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

Inclusion Criteria

  • Consecutive patients presenting with syncope or near syncope without any of the predefined exclusion criteria

Exclusion Criteria

  • Trauma-related loss of consciousness
  • Alcohol-related loss of consciousness
  • Drug-related loss of consciousness
  • Definite seizure
  • LOC associated with an altered level of consciousness or persistent new neurologic deficits did not meet operational definition of syncope and were excluded

Interventions

Outcomes

  • 30 day follow-up after the patients' index ED visit to determine serious short-term outcomes
  • Serious short-term outcomes defined as: death, myocardial infarction, arrhythmia, pulmonary embolism, stroke, subarachnoid hemorrhage, significant hemorrhage or anemia requiring transfusion, procedural intervention to treat a related cause of syncope or any condition likely to cause a return ED visit, and hospitalization for a related event

Primary Outcome

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

Performance of the San Francisco Syncope Rule in the validation cohort

Decision Rule Yes No
Rule Positive 52 290
Rule Negative 1 370
  • Sensitivity 98% (95% CI 89% to 100%)
  • Specificity 56% (95% CI 52% to 60%)
  • Negative Predictive Value 99.7% (95% CI 98% to 100%)
  • Positive Predictive Value 15% (95% CI 12% to 20%)
  • Death: 3
  • Arrhythmia: 23
  • Myocardial Infarction: 11
  • Valvular Heart Disease: 1
  • Significant Hemorrhage: 7
  • TIA/Stroke: 3
  • Sepsis: 3
  • Admission after ED discharge: 3

Secondary Outcomes

  • Physicians accurately interpreted the rule 95% of the time
    • Physicians felt comfortable using the rule in 79% of the cases
    • Physicians felt neutral using the rule in 15% of cases
    • Physicians felt uncomfortable using the rule in 6% of cases
  • The San Francisco Syncope Rule would have classified 52% of the patients as high risk
    • Using the rule potentially would have decreased overall admissions by 7%
    • Applying the rule to only the 453 patients admitted might have decreased admissions by 24%

Subgroup analysis

Criticisms & Further Discussion

  • Patients from only one hospital enrolled in the study
  • Validation study is performed at the same center used to derive the original rule
  • Wide margin of error observed in sensitivity[2]
    • 98% [95% confidence interval 89% to 100%). Taking the lower limit of the confidence interval as the correct value, the clinical decision rule cannot be considered highly sensitive
      • For example, in 100 patients with syncope of undetermined cause on presentation, 11 discharged home could have an adverse outcome
  • 54 patients has serious outcomes, but only 53 patients had data forms prospectively completed. The patient without a data form was excluded from the sensitivity analysis

Funding

  • A career development grant from the National Institutes of Health available to Dr. James Quinn, MD, MS, primary investigator of the study

Further Reading

ACEP Clinical Practice Management: Management of Syncope

Complete Journal Club Article
Martin TP et al.. "Risk stratification of patients with syncope". Ann Emerg Med. 1997. 29:459-466.
PubMed
Complete Journal Club Article
Colivicchi F et al. "Development and prospective validation of a risk stratification system for patients with syncope in the emergency department: the OESIL risk score". Eur Heart J.. 2003. 24:811-819.
PubMed
Complete Journal Club Article
Sarasin FP, Hanusa BH, Perneger T, et al.. "A risk score to predict arrhythmias in patients with unexplained syncope". Acad Emerg Med. 2003. 10:1312-1317.
PubMed

See Also

References

  1. Quinn J, McDermott D, Stiell I, Kohn M, Wells G. Prospective validation of the San Francisco Syncope Rule to predict patients with serious outcomes. Ann Emerg Med. 2006 May;47(5):448-54. PubMed PMID: 16631985.
  2. Miller C, Hoekstra J. Prospective Validation of the San Francisco Syncope Rule: Will It Change Practice? Ann Emerg Med. 2006 May;47(5):455-56. PubMed PMID: 16631986

Authors:

Ross Donaldson