Cardiology/original research
Prospective Validation of the San Francisco Syncope Rule to Predict Patients With Serious Outcomes

Presented at the Society for Academic Emergency Medicine annual meeting, May 2004, Orlando, FL.
https://doi.org/10.1016/j.annemergmed.2005.11.019Get rights and content

Study objective

We prospectively validate the San Francisco Syncope Rule (history of congestive heart failure, Hematocrit <30%, abnormal ECG result [new changes or non–sinus rhythm], complaint of shortness of breath, and systolic blood pressure <90 mm Hg during triage).

Methods

In a prospective cohort study, consecutive patients with syncope or near syncope presenting to an emergency department (ED) of a teaching hospital were identified and enrolled from July 15, 2002, to August 31, 2004. Patients with trauma, alcohol, or drug-associated loss of consciousness and definite seizures were excluded. Physicians prospectively applied the San Francisco Syncope Rule after their evaluation, and patients were followed up to determine whether they had had a predefined serious outcome within 30 days of their ED visit.

Results

Seven hundred ninety-one consecutive visits were evaluated for syncope, representing 1.2% of all ED visits. The average age was 61 years, 54% of patients were women, and 59% of patients were admitted. Fifty-three visits (6.7%) resulted in patients having serious outcomes that were undeclared during their ED visit. The rule was 98% sensitive (95% confidence interval [CI] 89% to 100%) and 56% specific (95% CI 52% to 60%) to predict these events. In this cohort, the San Francisco Syncope Rule classified 52% of the patients as high risk, potentially decreasing overall admissions by 7%. If the rule had been applied only to the 453 patients admitted, it might have decreased admissions by 24%.

Conclusion

The San Francisco Syncope Rule performed with high sensitivity and specificity in this validation cohort and is a valuable tool to help risk stratify patients. It may help with physician decisionmaking and improve the use of hospital admission for syncope.

Introduction

Approximately a quarter of the population will experience syncope (fainting) during their lifetime. Frequently, these patients will present to emergency departments (EDs), accounting for 1% to 2% of all ED visits and hospital admissions.1, 2, 3, 4, 5 Syncope occurs in the old and the young; it can be infrequent or recurrent; and although usually a benign symptom, it is occasionally associated with significant morbidity, such as arrhythmia, myocardial infarction, pulmonary embolism, occult hemorrhage, or death.6, 7, 8, 9 As a result, syncope is often referred to a “low-risk/high-stakes” symptom,10 with physicians admitting many patients who they believe are at low risk because of the high stakes if something adverse happens.

It is estimated that the cost of admission because of syncope in the United States may be as high as $2 billion annually.11 Specialty guidelines have tended to be conservative on admission recommendations, often citing a lack of clear evidence or criteria, and it is unclear if followed whether these recommendations would lead to an increase or decrease in admissions.12, 13, 14, 15 Furthermore, it has been demonstrated that many patients who are admitted receive little or no diagnostic evaluation as part of inpatient care.16, 17 This inefficient use of expensive hospitalization has resulted in a need for a more cost effective approach.18, 19, 20, 21, 22, 23, 24

We believe efficiencies can be realized through improved risk stratification and started a multiphase study to address this important problem. Using strict methodologic criteria for decision rule development, we first derived the San Francisco Syncope Rule, as illustrated in the Figure. We believe this highly sensitive clinical decision rule can augment physician judgment and allow physicians to rationally decide which patients with syncope need admission.4, 25 The purpose of this study is to validate the decision rule in a prospective cohort of consecutive ED patients by determining whether it can predict short-term serious outcomes not determined during the initial ED evaluation.

Section snippets

Setting

This prospective cohort study was conducted at the ED of the University of California at San Francisco, a large university teaching hospital. It received approval from the institution’s Committee on Human Research. Patients presenting with acute syncope or near syncope for their ED visit were considered for the study. To identify patients, we informed physicians that we were doing the study and used an electronic tracking system to identify all possible patients with a symptom of syncope.26 As

Results

During the study period, 760 patients had 791 visits for syncope, representing 1.2% of all ED visits. Of the 791 visits, physicians prospectively completed forms for 767 of the visits, and direct follow-up was completed on 752 visits. We were unable to directly contact 39 patients (5%) but found through a check of local hospitals and the Social Security Death Index that there were no unknown local admissions or deaths among these 39 patients.

The average age in the cohort was 61 years, 54% were

Limitations

This study did have some challenges and limitations. Despite our study’s size, all our patients came from a single hospital, although the demographics and admission rates of our patients appear to parallel those reported from other centers in the United States and Europe.27, 28, 29, 30 Also, decision rules have traditionally focused on areas in which the outcome measure is discrete, clearly defined, and easily measured, such as fracture versus no fracture on radiograph.31 For the purpose of a

Discussion

In this prospective validation study of consecutive ED patients with syncope, we have demonstrated that patients with undeclared serious outcomes can be accurately predicted by our previously derived clinical decision rule. If the decision rule were used to improve risk stratification and augment physician judgment, it could save millions of dollars by improving the use of hospital admission for patients with syncope.11

Evidence demonstrates that many admissions for syncope are inefficient. In

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    Supervising editor: Judd E. Hollander, MD

    Author contributions: JQ, IS, and GW conceived and designed the trial. JQ, DM, and MK supervised the conduct of the trial and data collection and provided database management and quality control. JQ, IS, MK, and GW contributed to the statistical analysis with advice, with JQ and IS doing the primary analysis. JQ drafted the manuscript, with all authors contributing significantly to its revisions. JQ takes responsibility for the paper as a whole.

    Funding and support: JQ is funded through a career development grant from the National Institutes of Health, K23, AR002137-050.

    Reprints not available from the authors.

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