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Aspirin may not benefit patients with peripheral vascular disease
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Patients with peripheral vascular disease who took aspirin did not experience improved CV outcomes, according to a study in PLOS ONE.
“Aspirin might not be a miracle drug for certain patients,” Ahmed N. Mahmoud, MD, a cardiovascular medicine fellow at the University of Florida in Gainesville, said in a press release. “We need to reconsider the evidence and see who benefits from aspirin therapy and who does not.”
Researchers reviewed data from 11 randomized controlled trials that compared the effects of aspirin with a placebo or control in 6,560 patients (mean age, 62 years; 60% women) aged 18 years or older with a history of peripheral vascular disease. Patients were previously assigned aspirin (n = 3,290) or a placebo or no aspirin (n = 3,270). In the pooled cohort, 32% had diabetes and 67% were current or former smokers.
All-cause mortality was the primary efficacy outcome. Secondary efficacy outcomes included stroke, MI and major adverse cardiac and cerebrovascular events. Major bleeding was the primary safety outcome, and the secondary safety outcome was intracranial hemorrhage. Weighted mean follow-up was approximately 6 years for all outcomes, except for intracranial hemorrhage, which was 7.8 years.
Outcomes similar
Incidence of all-cause mortality (RR = 0.93; 95% CI, 0.8-1.1) was similar in the aspirin (7.7%; 95% CI, 4.3-11.1) and control groups (8.5%; 95% CI, 4.6-12.5) at follow-up.
Comparable rates of MI were seen in the control (5.5%; 95% CI, 3.15-7.86) and aspirin (3.6%; 95% CI, 1.63-5.5) groups (RR = 0.91; 95% CI, 0.67-1.23). Stroke (RR = 0.72; 95% CI, 0.43-1.22) affected 4% of the control group (95% CI, 2-6) vs. 3.2% in the aspirin group (95% CI, 1.3-5.1).
“Among patients with peripheral vascular disease, many of them may not be deriving the benefits from aspirin that they expect to be getting,” Anthony A. Bavry, MD, associate professor in the department of medicine at University of Florida College of Medicine, cardiologist at Malcom Randall Veterans Affairs Medical Center, Gainesville, and a member of the Cardiology Today’s Intervention Editorial Board, said in the release.
Researchers also noted similarities in major adverse cardiac and cerebrovascular events (RR = 1; 95% CI, 0.83-1.2, where it was seen in 9.3% of aspirin group (95% CI, 4.8-13.9) and 11.6% of the control group (95% CI, 7.2-16; RR = 1; 95% CI, 0.42-1.22).
No difference in bleeding
Major bleeding occurred in 1.3% (95% CI, 0.3-2.3) of the aspirin group and 1.1% (95% CI, 0.7-1.6) of the control group (RR = 1.59; 95% CI, 0.96-2.62).
The rate of intracranial hemorrhage (RR = 1.38; 95% CI, 0.59-3.21) in patients assigned aspirin was 0.7% (95% CI, 0.3-1) vs. 0.4% in the control group (95% CI, 0.2-0.7).
“Aspirin use in [patients with peripheral vascular disease] might not be associated with improved [CV] outcomes,” Mahmoud and colleagues wrote. “However, most of the trials addressing the topic appear to be older trials with unclear risk of bias and outcomes definitions. Thus, larger randomized trials assessing the efficacy and safety of aspirin in the contemporary era of statins use are mandatory to confirm the current findings. The universal recommendation for aspirin therapy among patients with stable [peripheral vascular disease] needs to be re-examined.” – by Darlene Dobkowski
Disclosure: The researchers report no relevant financial disclosures.
Perspective
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Maya Serhal, MD
Mahmoud and colleagues have performed a meta-analysis of randomized controlled trials to better elucidate the efficacy and safety of aspirin in patients with peripheral vascular disease. Notably, the majority of patients included in the meta-analysis were from the AAA and POPADAD trials; both used a nonstandard method of ankle-brachial index measurement to define patients with peripheral artery disease. In light of this, this meta-analysis does not capture the sicker patients with PAD.
The findings of this analysis can be extrapolated in clinical practice to patients with borderline ankle-brachial index or mild PAD (by ankle-brachial index) who are asymptomatic, with no other indication for aspirin therapy.
This is largely consistent with the PAD treatment recommendations recently published — there is a class IIb recommendation stating that the usefulness of antiplatelet therapy in patients who are asymptomatic with a borderline ankle-brachial index is unknown. There is a class IIa recommendation stating it is reasonable to use antiplatelet therapy in patients who are asymptomatic with an ankle-brachial index less than 0.9.
A dedicated study reviewing the benefits of antiplatelet therapy in patients who are asymptomatic with ankle-brachial index less than 0.9 would be helpful to better define the role of antiplatelet therapy in this population. Additionally, there remains uncertainty regarding efficacy of aspirin in patients with PAD with significantly low ankle-brachial index.
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