Across-the-board use of aspirin for primary prevention is “not justified” based on the results of ASPREE as well as the equivocal results from other recent primary prevention trials, according to Prakash C. Deedwania, MD, clinical professor of medicine and chief of the cardiology division at the Veterans Affairs Medical Center/University of California San Francisco Program in Fresno.
Dr. Prakash C. Deedwania
The importance of interpreting these studies lies in the recognition that while low-risk people don’t benefit, patients who are at mid to high cardiovascular (CV) risk clearly might. Aspirin’s role in secondary prevention after an initial CV event is clearly established, Dr. Deedwania added.
In ASPREE, a randomized, double-blind, placebo-controlled trial including nearly 20,000 participants, daily aspirin increased rates of major hemorrhage and did not significantly decrease risks of cardiovascular events, death, or other outcomes in healthy elderly individuals.
Aspirin did not prolong disability-free survival, a composite endpoint that included death, dementia, and permanent physical disability, according to one of three separate reports on ASPREE that were published in the New England Journal of Medicine.
Cardiovascular disease rates were likewise not significantly different between aspirin and placebo, with a hazard ratio that ruled out the possibility of a major protective effect, lead author John J. McNeil, MBBS, PhD, of Monash University, Melbourne, said in a second report on ASPREE.
All-cause mortality was actually higher in the aspirin arm versus the placebo arm, attributable largely to an excess of cancer-related deaths, Dr. McNeil and colleagues said in their third full report in the journal. However, that mortality finding needs to be interpreted with caution, they noted, given that previous investigations have shown a protective effect of aspirin on cancer-related death.
Potential harms of “innocuous” drug
The ASPREE (Aspirin in Reducing Events in the Elderly) study evaluated the use of aspirin as primary prevention in 19,114 healthy subjects, with a median age of 74 years, enrolled at 34 centers in Australia and the United States between 2010 and 2014.
The patients, who did not have cardiovascular disease, dementia, or disability at baseline, were randomized to daily 100-mg enteric-coated aspirin or placebo.
The rate of death, dementia, or disability was 21.5 events per 1,000 person-years in the aspirin group, and 21.2 events per 1,000 person-years in the placebo group, with a hazard ratio of 1.01 (95% confidence interval, 0.92-1.11; P = .79), Dr. McNeil and colleagues reported.
The rate of major hemorrhage was 8.6 events per 1,000 person-years for aspirin versus 6.2 events per 1,000 person years for placebo (HR, 1.38; 95% CI, 1.18-1.62; P less than .001), investigators found.
Cardiovascular outcomes: expectations vs. reality
Investigators said they thought they might see a significant cardiovascular benefit of aspirin in ASPREE based on earlier studies and meta-analyses that suggested a benefit in other populations. However, the rate of cardiovascular disease at 4.7 years of follow-up was 10.7 events per 1,000 person-years for aspirin, and 11.3 per 1,000 person years for placebo (HR, 0.95; 95% CI, 0.83-1.08).