The Great White North is the land of clinical decision instruments. Canadian Head, Canadian C-Spine, Ottawa Ankle, Ottawa SAH, the list goes on – and now, from the same esteemed group: the Canadian Syncope Risk Score.
The vast majority of patients with syncope have unrevealing initial and, if admitted, in-house evaluation. That said, any physiologic interruptions in the ability to perfuse the brain portend a poor prognosis greater than the general background radiation. These authors performed an observational study over the course of four years to prospectively derive a decision instrument to support risk-stratification for syncope.
There were 4,030 patients enrolled and eligible for analysis based on 30-day follow-up, and 147 of these suffered a “serious adverse event”. They identified 43 candidate predictors for prospective collection, and ultimately this resulted in a multivariate logistic regression predictive model with 9 elements. Scores range from -3, with a 0.4% estimated risk for SAE, to 11, with an 83.6% estimated risk for SAE. Useable confidence intervals, however, were mostly scores <5.
There are a few things I would quibble with regarding this study. The “serious adverse event” definition is rather broad, and includes 30-day events for which the underlying pathology was not present or necessarily preventable at the initial visit. For example, a patient with a subsequent encounter for a GI bleed or a case of appendicitis fit their criteria of SAE. This would diminish the instrument’s apparent sensitivity without materially improving its clinical relevance. Then, there is the oddity of incorporating the final ED diagnosis into the scoring system – where a provisional diagnosis of “vasovagal syncope” is -2, and a diagnosis of “cardiac syncope” is +2. The authors explicitly defend its inclusion and the methods behind it – but I feel its subjectivity coupled with widespread practice variation will impair this rule’s generalizability and external validation.
Finally, the last issue with these sorts of “rules”: “high risk” is frequently conflated to mean “admit to hospital”. In many situations close to the end-of-life, the protective effect of hospitalization and medical intervention vanishes – and may have little or no value. This sort of stratification should be applied within the appropriate medical and social context, rather than simply triggering admission.
“Development of the Canadian Syncope Risk Score to predict serious adverse events after emergency department assessment of syncope”
http://www.ncbi.nlm.nih.gov/pubmed/27378464
Troponin inclusion…. baffling..