Diagnosing vasovagal syncope based on quantitative history-taking: validation of the Calgary Syncope Symptom Score

Area of Science:

• Cardiology
• Neurology
• Clinical Diagnostics

Background:

• Vasovagal syncope is the most common cause of transient loss of consciousness (T-LOC).
• Distinguishing vasovagal syncope from other causes of syncope via history alone is challenging.
• The Calgary Syncope Symptom Score (Calgary Score) was developed to aid in this differentiation.

Purpose of the Study:

• To evaluate the performance of the Calgary Score in a series of patients presenting with T-LOC.
• To assess the sensitivity and specificity of the Calgary Score in a real-world hospital setting.

Main Methods:

• The Calgary Score was calculated for 380 patients presenting with T-LOC.
• Diagnoses based on the Calgary Score were compared with final diagnoses after further testing and 2 years of follow-up.

Main Results:

• The Calgary Score demonstrated a sensitivity of 87% (95% CI: 82-91%) but a significantly lower specificity of 32% (95% CI: 24-40%).
• The score's discriminative ability for individual items was reduced compared to the original study population.
• Misclassification of syncope as vasovagal occurred frequently in patients with psychogenic pseudosyncope (21% specificity) and cardiac syncope (32% specificity).

Conclusions:

• While sensitivity was comparable to previous findings, the Calgary Score's low specificity limits its utility in general hospital settings for patients with T-LOC.
• The tool's value is constrained in differentiating vasovagal syncope from other syncope etiologies in a broad patient population.