Dutta D, Bowen E, and Foy C. Four Year Follow Up of Transient Ischemic Attacks, Strokes, and Mimics: A Retrospective Transient Ischemic Attack Clinic Cohort Study. Stroke. 2015
Frequently, patients who have transient neurologic symptoms are referred to the emergency department where they may receive further work-up. The usual TIA work-up may ensue after more precise questioning and examination are performed to rule out TIA mimics.
Several studies have been conducted to evaluate the prognosis and outcome of patients after TIA is diagnosed in the hospital or emergency department. The study by Dr. Dutta and colleagues is different because it aimed to determine the prognosis and outcome of patients who were evaluated for TIA at designated daily TIA clinics, based on the EXPRESS study model.
Although the great majority of patients referred to TIA clinics by non-specialists end up being TIA mimics, there may be a difference in the way they are managed as compared with the ED or hospital. This may be due to the fact that several studies have shown that the TIA mimics are often the result of posterior circulation insufficiency, coronary events or dementia. Therefor a more specialized work-up may be necessary to distinguish these cases.
This study was conducted in the UK and derived data from the TIA clinics of Gloucestershire Royal Hospital (GRH) between April 2010 and May 2012. The majority of practitioners that referred to the GRH were EDs, GPs and paramedics. After a patient was referred to the TIA clinic, they would have their risk factors evaluated, a history and exam would be done along with same-day investigations of CT head, carotid duplex ultrasounds, EKGs as well serum studies. If patients needed MRIs, echocardiograms, Holter monitoring or angiograms, these were done subsequently as required. Patients received treatment the same day as well, with statins, anti-platelet agents or oral anti-coagulants (if AF was diagnosed).
The outcome measures were pre-defined as stroke, MI, any vascular event (TIA, stroke or MI) and all-cause mortality. These were assessed by reviewing hospital records electronically and not by direct patient contact. The investigators looked at subsequent hospital admissions, discharge summaries, outpatient referrals and death. There were no patients lost to follow up and statistical analysis was done by univariate comparison of the TIAs, stokes and mimics with the chi-squared and Kruskal-Wallis tests.
In all, there were 1067 patients that were included in the study who presented to the TIA clinic within the time period of April 2010 and May 2012. Of these patients, 337 were diagnosed with TIA, while 189 were actually strokes and 538 were mimics. The median follow-up period was for 34.9 months. At 90 days, 0.9% of TIAs had a stroke, 2.1% of patients with strokes had a subsequent stroke and 0.2% of mimics had suffered a stroke. Subsequent strokes occurred in 7.1% of patients with TIA, 10.9% of patients with stroke and 2.0% of mimics by the 50-month period of follow up.
Overall, the 90-day risk of subsequent stroke for patients receiving services at these daily TIA clinics was 1.3%. This rate is much lower than that demonstrated by prior studies conducted on TIA patients in the mid-2000s that ranged from 7.5%-9.4%. If these numbers are actually representative of reality, then they imply a reduction of stroke in TIA patients by over 80%!
Why was this number so low compared to historical rates? The investigators believed that this was due to the earlier and more focused treatment of stroke risk factors. These patients received their prescriptions in-hand after their evaluation and were quickly and appropriately assessed in these specialized clinics.
These results sound encouraging and are hinting toward the potential benefit of developing more daily TIA clinics. However, this study should be reproduced in a prospective manner with actual patient assessment and evaluation as opposed to a review of electronic medical records. At any rate, the dramatic reduction of subsequent stroke or MI after TIA as compared to historical controls is promising!