Non-consensus transient ischemic attacks linked to high short-term and long-term risks of stroke  

1. Risk of recurrent stroke within 90 days of an index event was comparable among patients with non-consensus TIA and classic TIA.

2. Patients with non-consensus TIA were less likely to seek medical attention after the index event.

Evidence Rating Level: 2 (Good)

Study Rundown: The risk of stroke following a transient ischemic attack (TIA) is high and urgent intervention is needed. Patients with non-consensus events are often not investigated or treated as TIAs in practice. Additionally, little data remains available for the long-term risk of these patients compared to those with classic TIA. This study aimed to report the incidence, clinical characteristics, and prognosis of non-consensus TIAs compared with classic TIAs. Primary objectives for this study were to assess the 7-day, 90-day, and 10-year risks of stroke, as well as risks of all major cardiovascular events from the time of first event or from the time of seeking medical attention. According to study results, the 90-day and 10-year stroke risks from time of index event after a non-consensus TIA was similar to that after a classic TIA. Patients with non-consensus TIA were significantly less likely to seek medical attention following an event compared to those with classic TIA. However, among those with non-consensus TIA who sought medical attention, the 7-day stroke risk was higher than the expected background risk. A major strength of this study was the large sample size and longitudinal follow-up as the risk of stroke was assessed for several years after the index event. Overall, this study provided valuable insight into the early and long-term risks of stroke associated with non-consensus TIAs.

Click to read the study in The Lancet

Relevant Reading: Incidence of Transient Ischemic Attack and Association With Long-term Risk of Stroke

In-depth [prospective cohort]: Between Apr 1, 2002, and Mar 31, 2018, 2878 patients (1287 with minor ischemic stroke, 1021 with classic TIA, and 570 with non-consensus TIA) were enrolled across ten primary care practices in Oxford, UK. Patients who presented to the hospital with minor ischemic stroke, classic TIA, or non-consensus TIA were included in this study, irrespective of age. Those with positive visual or sensory symptoms or progressive symptoms suggestive of transient neurological attacks were excluded. Severity of stroke was assessed using the National Institutes of Health Stroke Scale (NIHSS).

Patients with non-consensus TIA were younger compared to those with classic TIA (mean age 68.5 years vs. 72.9 years, p<0.0001), had fewer previous strokes (4% vs. 7%, p=0.038), and were less likely to be on antithrombotic drugs (31% vs. 37%, p=0.015). During 17 009 person-years of follow-up, 577 patients had a first recurrent stroke after the index event. Patients with non-consensus TIA (10.6%, 95% confidence interval [CI] 7.8-12.9) had a similar 90-day stroke risk to patients with classic TIA (11.6%, 95% CI 9.6-13.6, hazard ratio [HR] 0.87, 95% CI 0.64-1.19, p=0.43), and higher than after amaurosis fugax (4.3%, 95% CI 0.6-8.0, p=0.042). The 10-year risk of all major vascular events was also similar for non-consensus and classic TIAs (27.1%, 95% CI 22.8-31.4 vs. 30.9%, 95% CI 27.2-33.7, p=0.12). However, patients with non-consensus TIA were less likely to seek medical attention following an index event than those with classic TIA (59% vs. 75%, odds ratio [OR] 0.47, 95% CI 0.38-0.59, p<0.0001). As a result, they were more likely to have repeated strokes prior to medical attention (8% vs. 5%, OR 1.77, 95% CI 1.16-2.71, p=0.007). Upon adjusting for this, the 7-day stroke risk for non-consensus TIA (2.9%, 95% CI 1.5-4.3) was higher than the background risk (relative risk [RR] 203, 95% CI 113-334). Overall, findings from this study suggest that monosymptomatic events such as non-consensus TIAs should be managed as TIAs and should not be excluded from treatment trials.

Image: PD

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