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

Aims: It can be difficult to distinguish vasovagal syncope, the most common cause of transient loss of consciousness (T-LOC), from other causes of syncope by history taking. The Calgary Syncope Symptom Score (Calgary Score) is a tool developed for this purpose. We studied its performance in a series of patients presenting with T-LOC.

Methods And Results: We calculated the Calgary Score for 380 patients presenting with T-LOC to a number of departments of our university hospital. Diagnoses of vasovagal syncope based on the Calgary Score were then compared with the final diagnosis, obtained after additional testing and 2 years of follow-up. The sensitivity of the Calgary Score was 87% (95% CI: 82-91%), at a specificity of 32% (95% CI: 24-40%). Most items of the Calgary Score were less discriminative in our study group than in the original population. Incorrectly labelling patients with syncope as vasovagal was most common in patients with psychogenic pseudosyncope (specificity 21%) but also occurred in patients with cardiac syncope (specificity 32%).

Conclusion: The sensitivity of the Calgary Score was comparable with the one in the original study, but its specificity was much lower, limiting its value in patients presenting with T-LOC in a general hospital setting.