Aspirin for primary prevention does not reduce vascular events in adults aged ≥ 70 years and may increase rates of death and major bleeding

EBM Focus - Volume 13, Issue 32

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Reference: N Engl J Med 2018 Sep 16 early online (level 1 [likely reliable] evidence)

On the heels of the ASCEND trial that suggested aspirin for primary prevention in diabetic patients may slightly reduce serious vascular events at the cost of increased rates of major bleeding, a group of researchers conducted a randomized, double-blind, placebo-controlled trial to examine the benefits of aspirin for primary prevention among older adults. In the ASPREE trial (Aspirin in Reducing Events in the Elderly), researchers randomized over 19,000 community dwelling adults over age 70 living in Australia or the United States to either 100 mg of aspirin daily or placebo. After three years of data collection, the researchers added Black and Hispanic patients aged ≥ 65 in the US as inclusion criteria given the higher predicted event rates in this patient population. Patients with diabetes, dyslipidemia, and hypertension were included in the trial. Those with an indication for aspirin, anemia, limited life expectancy, dementia, or significant disability were excluded. The aspirin and placebo groups had similar baseline characteristics, with a median age 74 years at enrollment. Nearly ¾ of participants had hypertension and 65% of participants were diagnosed with dyslipidemia. The primary endpoint was disability free survival, defined as survival at the end of the trial free from dementia or physical disability.

After four years of follow up, the trial was ended for futility. There was no difference in the primary composite outcome of death, dementia, or physical disability in the aspirin compared to placebo group (95% CI, 0.92 -1.11). There were increased rates of all-cause mortality (95% CI, 1.01- 1.29) and major hemorrhagic bleeding (95% CI, 1.18 - 1.62) among the aspirin group compared to the placebo group. In a post-hoc analysis, colorectal cancer-specific deaths were increased in the aspirin group which largely contributed to the increased rate of all-cause mortality. This finding conflicts with current clinical practice and the proposed beneficial effects of aspirin therapy for the prevention of colorectal cancer.

Of note, the recent ARRIVE trial published in Lancet found no benefit for aspirin in reducing initial vascular events for men over 55 or women over 60 with moderate cardiovascular risk.

Focus Point: It is ever more apparent that age matters when it comes to prescribing aspirin for primary prevention. Older adults, including those with cardiovascular risk factors, do not benefit from primary prevention and may well be harmed.

For more information, see the topic Aspirin for primary prevention of cardiovascular disease in DynaMed Plus. DynaMed users click here.

DynaMed Plus EBM Focus Editorial Team

Alan Ehrlich, MD: Executive Editor at DynaMed Plus and Associate Professor in Family Medicine at the University of Massachusetts Medical School
Monica Zangwill, MD, MPH: Associate Deputy Editor at DynaMed Plus
Katharine DeGeorge, MD, MS: Clinical Editor at DynaMed Plus and Assistant Professor in Family Medicine at University of Virginia School of Medicine
Carina Brown, MD: Fellow at University of Virginia School of Medicine
Sarah Dalrymple, MD: Fellow at University of Virginia School of Medicine