The POISE 2 trial: Aspirin increases risk of major bleeding after noncardiac surgery [Classic Series]

1. After noncardiac surgeries, patients treated with aspirin had significantly increased risk of major bleeding compared to those taking placebo.

2. There was no significant difference in death or nonfatal myocardial infarction between the aspirin and placebo groups.

Original Publication Date: April 2014

Study Rundown: After a noncardiac surgery, myocardial infarction is one of the most common major complications that patients can experience. It is suspected that surgery leads to greater platelet activation and higher risk of coronary thrombus, resulting in perioperative infarctions. A meta-analysis of data from randomized trials has shown that the use of aspirin in nonsurgical patients prevented cardiovascular events. Moreover, high-dose aspirin has not been shown to be superior to low-dose, but has been linked to higher risk of gastrointestinal adverse effects. Prior to this study, practice regarding the use of perioperative aspirin was inconsistent.

The Perioperative Ischemic Evaluation 2 (POISE-2) trial sought to determine whether low-dose aspirin would alter the risk of death or nonfatal myocardial infarction in patients who underwent noncardiac surgery. The results from this study show that there were no significant differences between the aspirin group and the placebo group in the composite endpoint of death or nonfatal myocardial infarction at 30 days. Treatment with aspirin, however, significantly increased the risk of major bleeding as compared with placebo, with the most common sites of bleeding being the surgical site and the gastrointestinal tract.

Click to read the study in NEJM

In-Depth [randomized controlled trial]: This trial utilized a 2×2 factorial design. A total of 10 010 patients from 23 countries were randomized to receive either aspirin or placebo, and clonidine or placebo. This study reported on the comparison between aspirin and placebo. Any patient undergoing noncardiac surgery, 45 years of age or older, expected to require at least overnight admission to hospital, and cardiovascular risk factors (e.g., coronary artery disease, peripheral vascular disease, stroke, undergoing major vascular surgery) was eligible for the study. Exclusion criteria included taking aspirin within 72 hours of surgery, hypersensitivity or known allergy to aspirin or clonidine, systolic blood pressure <105 mm Hg, heart rate <55 beats per minute without a pacemaker, and active peptic ulcer disease or gastrointestinal bleeding in the past 6 weeks. The primary outcome was a composite of death or nonfatal myocardial infarction in the 30 days after randomization.

The primary outcome occurred in 7.0% of the aspirin group and 7.1% in the placebo group (HR 0.99; 95%CI 0.86-1.15; p = 0.92). Major bleeding was significantly more common in patients taking aspirin (4.6% vs. 3.8%; HR 1.23; 95%CI 1.01-1.49; p = 0.04). Patients taking aspirin were found to have significantly higher risk of bleeding until post-operative day 6, at which point the bleeding risk was not significantly different between the two groups. Bleeding most commonly occurred at the surgical site (78.3%) and in the gastrointestinal tract (9.3%).

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