The United Kingdom Transient Ischemic Attack Aspirin Trial: Final Results - UK-TIA

Description:

The goal of this study was to assess the safety and efficacy of low dose and high dose aspirin therapy versus placebo among patients with a recent transient ischemic attack (TIA) or minor ischemic stroke.

Hypothesis:

At the time the study was performed, no evidence existed that antiplatelet therapy in excess of 300 mg daily offered any increased benefit. The investigators hypothesized that low dose aspirin (300 mg per day) would prove to be more efficacious than placebo in secondary prevention after TIA or minor stroke. It was further hypothesized that there would not be a significant difference between the efficacy of low dose and high dose (1200 mg daily) aspirin therapy.

Study Design

Study Design:

Patients Enrolled: 2,435
Mean Follow Up: Mean follow-up was four years
Mean Patient Age: Mean age was 60 years
Female: 27

Patient Populations:

Patients were eligible to participate if they had a TIA or minor stroke within the past three months.

Exclusions:

Exclusion criteria included: age <40, TIA or minor stroke occurring >3 months ago, prior major debilitating stroke, patients whose symptoms were definitely due to something other than thromboembolic disease, previous aspirin allergy or intolerance, previous abnormal bleeding, alcoholism, chronic renal failure, peptic ulcer disease within the prior three years, MI within the prior three months, the need for regular aspirin therapy, aspirin therapy within the prior 90 days, low likelihood of follow-up or compliance, or patients with severe recurrent nonvascular disease.

Primary Endpoints:

The primary endpoint was the combination of the occurrence of major stroke, MI, or vascular death. Vascular death was defined as all deaths that were not definitively nonvascular including: fatal stroke, fatal MI, sudden death, ruptured aortic aneurysm, death from other ischemic heart disease, death from other vascular disease, fatal GI hemorrhage, and death from unknown cause.

Secondary Endpoints:

Adverse effects included: upper GI symptoms, constipation, abdominal flatulence, diarrhea, GI hemorrhage, bruising, nose bleed, retinal hemorrhage, other bleeding, gout, tiredness, skin rash, dizziness, tinnitus, depression, irritability, and wheezing.

Drug/Procedures Used:

Eligible patients were randomized to receive low dose aspirin, high dose aspirin, or placebo. Patients in the low dose aspirin therapy group received two 150 mg tablets orally every morning and two placebo tablets every evening for a total of 300 mg per day. Patients in the high dose group received two 300 mg tablets orally every morning and an additional two 300 mg tablets every evening for a total of 1200 mg per day. Patients in the placebo group received two placebo tablets twice per day.

Principal Findings:

There was a strong trend toward a reduction in the odds of the primary combined endpoint of major stroke, myocardial infarction (MI), or vascular death of 15% among patients treated with aspirin compared to placebo (95% confidence interval [CI] 29% odds reduction to 3% odds increase). Patients in the aspirin group had a significant reduction in the odds of nonvascular death of 45% compared to placebo (95% CI 11-66% odds reduction).

There was no significant difference between patients in the two aspirin groups in the incidence of the primary endpoint; however, patients in the high dose group were significantly more likely to experience upper gastrointestinal (GI) symptoms (odds ratio [OR] 1.54, 95% CI 1.25-1.89) and there was a strong trend toward an increase in GI hemorrhage (OR 1.62, 95% CI 0.94-2.79) with the increased dose.

Interpretation:

Among patients with a recent TIA or minor ischemic stroke, aspirin therapy was associated with a trend toward a reduction in major stroke, MI, or vascular death when compared to placebo. Additionally, there was no significant difference in the incidence of the primary endpoint between the high and low dose aspirin groups, while there was an increase in the occurrence of GI side effects in patients in the high dose group. These findings suggest that low dose aspirin may be superior to placebo in the management of patients with TIA or ischemic stroke and that high dose aspirin therapy offers no increased benefit and is associated with increased GI side effects.

References:

Farrell B, Godwin J, Richards S, Warlow C. The United Kingdom transient ischaemic attack (UK-TIA) aspirin trial: final results. J Neurol Neurosurg Psychiatry 1991;54:1044-54.

Clinical Topics: Vascular Medicine

Keywords: Odds Ratio, Myocardial Infarction, Stroke, Ischemic Attack, Transient, Platelet Aggregation Inhibitors, Cerebrovascular Disorders, Confidence Intervals, Gastrointestinal Hemorrhage


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