The study by the National Institute on Aging produced a few surprises and was stopped early when aspirin showed no benefit.
The recommendation to take low-dose aspirin each day is not for everyone, according to a new study.
A large clinical trial involving more than 19,000 people in Australia and the United States found that a daily low-dose aspirin did not prolong life in healthy older people, and in fact increased the likelihood of a major hemorrhage. Results appeared Sunday in the New England Journal of Medicine.
Aspirin has been shown to help prevent cardiovascular events in people who already have a history of coronary heart disease or stroke. The US Preventive Service Task Force gives a “B” rating to initiating low-dose aspirin for primary prevention of cardiovascular disease and colorectal cancer in adults aged 50 to 59 years who have a 10% or greater risk of cardiovascular disease, are not at increased risk of bleeding, have a life expectancy of at least 10 years, and are willing to take low-dose aspirin daily.
But whether aspirin use would benefit otherwise healthy older adults was not known. The authors noted that whereas most trials involving aspirin have focused on avoiding cardiovascular events, this one focused looked at the long-term use of a preventive drug for its ability to sustain “a healthy independent state.”
“By reducing platelet aggregation and thrombotic obstruction, thereby lessening the risk of ischemia in the heart, brain, and other organs, aspirin may be expected to reduce the incidence of disability from various causes,” the authors wrote. The offset, of course, is the risk of bleeding; the primary end point of disability-free survival incorporated the hopes for a low-cost preventive drug in an otherwise healthy population.
The study, called ASPREE, ran from 2010 to 2014 and involved adults at least 70 years of age, or 65 years of age if they were African-American or Hispanic, as these groups have higher risks of dementia and cardiovascular disease. A total of 9525 people received 100 mg of low-dose aspirin, and 9589 received placebo. Of the participants, 56.4% were women, 8.7% were nonwhite, and 11.0% reported previous aspirin use.
The trial ended after 4.7 years of follow-up, once it was shown that there was no benefit with continued aspirin use. The rates of a composite of death, dementia, or persistent physical disability were 21.5 events per 1000 person-years in the aspirin group and 21.2 events per 1000 person-years in the placebo group. Rates for cardiovascular events (including coronary heart disease, nonfatal heart attacks, and strokes) were similar in the 2 groups: 448 people in the aspirin group had events, compared with 474 in the placebo group.
Taking aspirin had no effect on whether people experienced dementia or disability; 90.3% in the aspirin group remained alive with no persistent physical disability or dementia, compared with 90.5% on placebo. But those taking aspirin were more likely to experience bleeding, such as hemorrhages.
Those taking aspirin had an elevated risk of death—5.9% compared with 5.2% taking placebo. This has not been seen in earlier studies and was primarily due to higher death rates among patients who developed cancer. 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 state. Cancer was a common cause of death among both groups, as would be expected in an older population; it accounted for 50% of all deaths during the trial.
“This study shows why it is so important to conduct this type of research, so that we can gain a fuller picture of aspirin's benefits and risks among healthy older persons,” said Richard J. Hodes, MD, the director of the National Institute on Aging (NIA), in a statement. The agency funded the study.
Adherence was 62.1% in the aspirin group and 64.1% in the placebo group in the last year of the trial.
“Continuing follow-up of the ASPREE participants is crucial, particularly since longer term effects on risks for outcomes such as cancer and dementia may differ from those during the study to date,” said Evan Hadley, MD, director of NIA's division of Geriatrics and Clinical Gerontology. The number of cancer deaths was a surprise. “These initial findings will help to clarify the role of aspirin in disease prevention for older adults, but much more needs to be learned. The ASPREE team is continuing to analyze the results of this study and has implemented plans for monitoring participants.”
McNeil JJ, Woods RL, Nelson MR et al. Effect of aspirin on disability-free survival in the healthy elderly [published September 16, 2018]. N Engl J Med. doi: 10.1056/NEJMoa1800722.