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Effect of Aspirin on Disability-free Survival in the Elderly

ORIGINAL ARTICLE

Effect of Aspirin on Disability-free Survival in the Healthy Elderly

J.J. McNeil and Others

McNeil et al. conducted the randomized, placebo-controlled Aspirin in Reducing Events in the Elderly (ASPREE) trial to investigate whether the daily use of aspirin, at a dose of 100 mg, in healthy, community-dwelling older adults would prolong a healthy life span, free from dementia and persistent physical disability. Trial participants were community-dwelling men and women from Australia and the United States who were 70 years of age or older (or ≥65 years of age among blacks and Hispanics in the United States).

Clinical Pearls

  Is there any evidence to support the use of aspirin for primary prevention of cardiovascular or other chronic disease in healthy older adults?

Several large, randomized trials have shown the efficacy of aspirin for the secondary prevention of cardiovascular disease among persons with a history of coronary heart disease or stroke. The evidence supporting a benefit of aspirin therapy in the primary prevention of cardiovascular or other chronic disease is less conclusive despite favorable trends suggesting that aspirin use reduces the incidence of cardiovascular events and possibly reduces the incidence of cancer and cancer-related mortality, particularly from colorectal cancer.

  Does the daily use of 100 mg of aspirin prolong a healthy lifespan in older adults without cardiovascular disease, dementia, or physical disability?

In the ASPREE trial, the daily use of 100 mg of enteric-coated aspirin did not differ significantly from placebo in influencing the rates of disability-free survival at a median of 4.7 years. The primary end point of death, dementia, or physical disability occurred in 921 participants in the aspirin group (21.5 events per 1000 person-years) and in 914 in the placebo group (21.2 events per 1000 person-years). The between-group difference was not significant (hazard ratio, 1.01; 95% confidence interval [CI], 0.92 to 1.11; P=0.79). Among participants who had a primary end-point event, death was the most common first event (in 911 participants [50% of the events] at a mean age of 77.5 years), dementia was the next most common (in 549 participants [30% of the events] at a mean age of 77.7 years), and persistent physical disability was the least common.

Morning Report Questions

Q. How does a daily aspirin dose of 100 mg influence rates of death from any cause and the risk of major hemorrhage in healthy older adults?

A. In the ASPREE trial, the secondary end point of death from any cause, denoting death as the first, second, or third event to occur in the primary end point, occurred in 558 participants in the aspirin group (12.7 events per 1000 person-years) and in 494 participants in the placebo group (11.1 events per 1000 person-years) (hazard ratio, 1.14; unadjusted 95% CI, 1.01 to 1.29). Because there was no adjustment for multiple comparisons of secondary end points, no inferences can be made regarding differences in mortality between the two groups. Major hemorrhage occurred in 3.8% of the participants in the aspirin group, as compared with 2.8% of those in the placebo group (hazard ratio, 1.38; 95% CI, 1.18 to 1.62; P<0.001). Fatal or nonfatal hemorrhagic stroke (including subarachnoid hemorrhage) occurred in 49 participants (0.5%) in the aspirin group and in 40 (0.4%) in the placebo group.

Q. How generalizable are the results of the ASPREE trial?

A. White participants comprised 91% of the overall trial cohort. Owing to the small number of blacks and Hispanics (including participants who were younger than 70 years of age) and other nonwhites, the applicability of the main findings of the ASPREE trial to these subgroups is unclear.

Daily Low-Dose Aspirin Found to Have No Effect on Healthy Life Span in Older People?

According to 3 articles published online The New England Journal of Medicine (16 September 2018), daily low-dose aspirin was found to have no effect on healthy life span in older people. This large NIH-funded study examined outcomes in United States and Australia

Results showed that in a large clinical trial to determine the risks and benefits of daily low-dose aspirin in healthy older adults without previous cardiovascular events,

Aspirin did not prolong healthy, independent living (life free of dementia or persistent physical disability).

Risk of dying from a range of causes, including cancer and heart disease, varied and will require further analysis and additional follow-up of study participants. These initial findings from the ASPirin in Reducing Events in the Elderly (ASPREE) trial, partially supported by the National Institutes of Health.

ASPREE is an international, randomized, double-blind, placebo-controlled trial that enrolled 19,114 older people (16,703 in Australia and 2,411 in the United States). The study began in 2010 and enrolled participants aged 70 and older; 65 was the minimum age of entry for African-American and Hispanic individuals in the United States because of their higher risk for dementia and cardiovascular disease. At study enrollment, ASPREE participants could not have dementia or a physical disability and had to be free of medical conditions requiring aspirin use. They were followed for an average of 4.7 years to determine outcomes.

In the total study population, treatment with 100 mg of low-dose aspirin per day did not affect survival free of dementia or disability. Among the people randomly assigned to take aspirin,

• 90.3% remained alive at the end of the treatment without persistent physical disability or dementia, compared with 90.5% of those taking a placebo.
• Rates of physical disability were similar, and rates of dementia were almost identical in both groups. However,
• the group taking aspirin had an increased risk of death compared to the placebo group: 5.9% of participants taking aspirin and 5.2% taking placebo died during the study.

This effect of aspirin has not been noted in previous studies; and caution is needed in interpreting this finding. The higher death rate in the aspirin-treated group was due primarily to a higher rate of cancer deaths. A small increase in new cancer cases was reported in the group taking aspirin but the difference could have been due to chance. The authors also analyzed the ASPREE results to determine whether cardiovascular events took place. They found that

• the rates for major cardiovascular events — including coronary heart disease, nonfatal heart attacks, and fatal and nonfatal ischemic stroke — were similar in the aspirin and the placebo groups. In the aspirin group, 448 people experienced cardiovascular events, compared with 474 people in the placebo group.

Significant bleeding — a known risk of regular aspirin use — was also measured. The authors noted that

• aspirin was associated with a significantly increased risk of bleeding, primarily in the gastrointestinal tract and brain. Clinically significant bleeding — hemorrhagic stroke, bleeding in the brain, gastrointestinal hemorrhages or hemorrhages at other sites that required transfusion or hospitalization — occurred in 361 people (3.8%) on aspirin and in 265 (2.7%) taking the placebo.
• As would be expected in an older adult population, cancer was a common cause of death, and 50% of the people who died in the trial had some type of cancer.
• Heart disease and stroke accounted for 19% of the deaths and major bleeding for 5%.

The ASPREE team is continuing to analyze the results of this study and has implemented plans for monitoring participants. As these efforts continue, the authors emphasized that older adults should follow the advice from their own physicians about daily aspirin use. It is important to note that the new findings do not apply to people with a proven indication for aspirin such as stroke, heart attack or other cardiovascular disease. In addition, the study did not address aspirin’s effects in people younger than age 65. Also, since only 11% of participants had regularly taken low-dose aspirin prior to entering the study, the implications of ASPREE’s findings need further investigation to determine whether healthy older people who have been regularly using aspirin for disease prevention should continue or discontinue use.