Written by Clay Smith
This retrospective application of the Canadian Syncope Risk Score (CSRS) on a different syncope cohort, for which some of the key variables of the CSRS had to be estimated or extrapolated, showed it performed similarly to clinical judgment. But this wasn’t the best design to address external validation of the CSRS in a demographically different cohort.
Why does this matter?
The CSRS was derived and validated in multiple Canadian ED settings, but how would it perform in a different demographic, such as this northern Italian cohort?
Canadian syncope in northern Italy?
This study was retrospective. They originally prospectively collected data for the SyMoNE study (Syncope Monitoring and Natriuretic peptides in the ED). The SyMoNE dataset included some of the variables needed to calculate the CSRS. There were 345 patients included in the SyMoNE study with syncope. When the CSRS was retrospectively applied to this cohort, the AUC was 0.75 (a measure of overall diagnostic accuracy), which was better than clinical judgment alone, with an AUC 0.68. But there were fewer adverse events when clinical judgment was used (2%) as opposed to the CSRS (6.7%). Although the original study cohort had many of the data points collected prospectively, this was still a retrospective overlay of the CSRS onto this cohort, which introduces the possibility of bias. There was no way for the authors to capture whether a patient had a predisposition to vasovagal syncope or to determine another critical element of the CSRS: final diagnosis of vasovagal or cardiac syncope. The authors acknowledge they had to extrapolate this information. The authors conclude that until further studies are done in additional populations, the CSRS should not be widely adopted. I’m not so sure. The CSRS was externally validated in 9 Canadian EDs in a study that was >10x larger than this one. There is no getting around the fact that the SyMoNE study was not intended to address the CSRS and did not collect the requisite information to accurately calculate the CSRS. In the end, I don’t think this study changes much. Based on data that is higher quality than this retrospective analysis, the CSRS performed well, and was better than other syncopes scores, like San Francisco.
Multicentre external validation of the Canadian Syncope Risk Score to predict adverse events and comparison with clinical judgement. Emerg Med J. 2021 May 26;emermed-2020-210579. doi: 10.1136/emermed-2020-210579. Online ahead of print.