Aspirin therapy may not help patients with PVD – meta-analysis

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AM4CCCAspirin use in peripheral vascular disease (PVD) might not be associated with improved cardiovascular outcomes or worse bleeding outcomes, a University of Florida Health meta-analysis found. Guideline recommendations regarding the use of aspirin among patients with PVD need to be updated.

Aspirin therapy has been a staple of cardiology care for people who have peripheral vascular disease, which causes narrowed arteries and reduced blood flow to the limbs. Now, UF Health researchers’ meta-analysis of 11 aspirin therapy trials involving 6,560 peripheral vascular disease (PVD) patients found that the drug has no significant effect on death rates and incidents of stroke, heart attack or major cardiac events.

“Among patients with peripheral vascular disease, many of them may not be deriving the benefits from aspirin that they expect to be getting,” said Dr Anthony A Bavry, an associate professor in the UF College of Medicine department of medicine and a cardiologist at the Malcom Randall Veterans Affairs Medical Centre in Gainesville.

Aspirin prevents blood clots from forming, which can reduce the risk of a stroke or heart attack. But it can also be a hazard: Blood that doesn’t clot easily can raise the risk of a haemorrhagic stroke or internal bleeding. Approximately 8.5m people in the US have peripheral vascular disease including up to 20% of those over age 50, according to the Centers for Disease Control and Prevention.

Among the major findings from the analysis: After about six years, 7.7% of PVD patients who took aspirin had died, compared with 8.5% in a control group. The incidence of stroke was 3.2% among aspirin users and 4% among non-users. Heart attacks were recorded in 3.5% of aspirin users and 5.5% of non-users. However, all differences did not reach statistical significance with overlapping confidence intervals. The prevalence of other major adverse cardiac and cerebrovascular events was similar among both groups.

The mean age of patients included in the analysis was 62 – 60% of the patients were women, 32% were people with diabetes and 67% were current or ex-smokers.

Aspirin’s role in causing major bleeding was less clear in the analysis: A review of seven trials found virtually no difference among aspirin users and nonusers, although there was a trend toward more major bleeding with aspirin and researchers said there wasn’t enough data to draw a definite conclusion.

While noting that the analysis is not the final word on aspirin’s effectiveness in PVD cases, the researchers said it is the most updated analysis that compares medical outcomes among those who use aspirin and those who do not. Among other factors, the analysis was limited by the large weight given to a single trial and the fact that many of the trials were done before cholesterol-reducing medications were common. Larger, randomised trials will be needed to confirm the findings that were revealed in the analysis, said Dr Ahmed N Mahmoud, a cardiology fellow in the department of medicine and a co-author of the study.

“Aspirin might not be a miracle drug for certain patients. We need to reconsider the evidence, and see who benefits from aspirin therapy and who does not,” he said.

Patients who are on a daily aspirin regimen for cardiovascular issues should not stop taking the medicine on their own but can consult their physician about whether the current findings may be relevant, Bavry said. For cardiologists and researchers, Bavry said the analysis underscores the need for further study. A study to assess aspirin’s risks and benefits in patients’ conditions such as stable ischemic heart disease, which stems from plaque buildup in arteries, is also underway, he added.

Background: Although considered a cornerstone therapy, the efficacy and safety of aspirin for prevention of ischemic events in patients with peripheral vascular disease (PVD) remains uncertain. Thus, we aimed to evaluate aspirin use in both symptomatic and asymptomatic patients with PVD.
Methods: An electronic search of databases was conducted from inception until January 2017 for all randomized trials comparing aspirin with either placebo or control (no aspirin) in patients with PVD. The primary efficacy outcome was all-cause mortality, and the primary safety outcome was major bleeding. Other outcomes of interest were major adverse cardiac and cerebrovascular events (MACCE), myocardial infarction (MI), stroke and intracranial hemorrhage. Random-effects summary risk ratios (RR) were calculated using Der-Simonian and Liard model. The quality of evidence was assessed by GRADE tool and Cochrane risk of bias assessment tool.
Results: A total of 6,560 patients from 11 trials were included. Only two trials were considered to have low risk of bias. Compared with control, aspirin was associated with similar incidence of all-cause mortality (RR = 0.93, 95% confidence interval [CI] 0.8–1.1), MACCE (RR = 1.0, 95% CI 0.83–1.20), MI (RR = 0.91, 95% CI 0.67–1.23) and stroke (RR = 0.72, 95% CI 0.43–1.22), major bleeding (RR = 1.59, 95% CI 0.96–2.62) and intracranial hemorrhage (RR = 1.38, 95% CI 0.59–3.21).
Conclusions: Aspirin use in PVD might not be associated with improved cardiovascular outcomes or worse bleeding outcomes. Larger randomized trials assessing the efficacy and safety of aspirin in the contemporary era are mandatory to confirm the current findings. Guideline recommendations regarding the use of aspirin among patients with PVD need to be updated.

Ahmed N Mahmoud, Akram Y Elgendy, Cecil Rambarat, Dhruv Mahtta, Islam Y Elgendy, Anthony A Bavry

University of Florida material
PLOS One abstract

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