Written by Clay Smith
The Canadian TIA Score has now been validated and is ready for clinical use. Patients with a clinically-defined TIA (no MRI) may be accurately stratified as low, medium, or high risk for subsequent stroke (+/- carotid revascularization) within 7 days.
Why does this matter?
ABCD2 has some issues for determining disposition in TIA patients. ABCD2i considered ABCD2 + presence of infarction on CT or DWI, which improved prediction of short-term stroke. Not unexpectedly, our northern neighbors are at it again and have now validated the Canadian TIA score, which was better than the made-in-California ABCD2 score.
This score looks good but note the TIA definition
This was a prospective cohort of 7,607 ED patients with TIA. For the primary outcome of stroke or carotid endarterectomy (CEA)/ carotid stenting within 7 days, the Canadian TIA Score performed well. For patients deemed low risk (score -3 to 3), the primary outcome occurred in 0.5%; medium risk (score 4 to 8), 2.3%; high risk (score ≥9), 5.9%. If they just considered stroke within 7 days and eliminated CEA/stenting, results were very similar but looked even better for subsequent stroke risk: low 0.2%; medium 1.5%; high 2.7%. The Canadian TIA score outperformed ABCD2 or ABCD2i when considering overall diagnostic accuracy (AUC). These days, the TIA definition includes resolved symptoms and negative MRI. That was not how it was defined in this study, and just 4.2% had MRI. Rather, it was an ED working diagnosis of TIA that warranted inclusion in the study. They used the old school definition of TIA. The majority of patients, 72%, fell into the medium risk group. These are tough to deal with, in my opinion. Lows can probably go home. Highs are probably admitted. But what should we do with medium risk? With a <2% 7-day stroke risk, one could argue that they could be sent home on aspirin with close follow up, ongoing workup, and modification of stroke risk factors. It sounds like there is room for shared clinical decision making here. But we will need to figure out how to manage this in our own practice settings.
QxMD has a Canadian TIA Score calculator.
Prospective validation of Canadian TIA Score and comparison with ABCD2 and ABCD2i for subsequent stroke risk after transient ischaemic attack: multicentre prospective cohort study. BMJ. 2021 Feb 4;372:n49. doi: 10.1136/bmj.n49.