An estimated 19 percent of U.S. adults report using aspirin regularly, often for its heart-protective benefits, and its use increases with age. Incidence of age-related macular degeneration also rises in older age, making this association important to examine, the study authors said. About 1.8 million Americans currently have the eye disease, which destroys sharp, central vision.
The study found that the potential risk is small but statistically significant “and needs to be balanced with the significant morbidity and mortality of undertreated cardiovascular disease,” said study senior researcher Jie Jin Wang, a senior research fellow at the Center for Vision Research at the University of Sydney.
Also, “the increased risk of age-related macular degeneration was only detected after 10 or 15 years, suggesting cumulative dosage of aspirin may be important,” Wang said.
Although aspirin is among the most effective cardiovascular disease preventives, regular use over the long term has been associated with adverse side effects, Wang added. Study results regarding aspirin’s link to macular degeneration have been inconsistent to date.
The report, published Jan. 21 in the online edition of the journal JAMA Internal Medicine, collected data on more than 2,300 people. Regular aspirin use was defined as once or more a week. As part of the study, the participants had four eye exams over 15 years.
Almost 11 percent of patients used aspirin regularly. After 15 years, about 25 percent of the aspirin users developed what is called neovascular age-related macular degeneration.
The cumulative rate was about 9 percent among aspirin users compared to less than 4 percent among non-aspirin users.
People taking aspirin for heart and stroke prevention benefits should not be alarmed, however, Wang said.
“Currently, there is insufficient evidence to recommend changing clinical practice, except perhaps in cases of patients with strong risk factors for age-related macular degeneration, such as existing age-related macular degeneration in one eye,” she said.
Other experts agreed.
“Randomized controlled trials of aspirin use with follow-up as long as 10 years have not demonstrated any increase in the risk of age-related macular degeneration,” said Dr. Gregg Fonarow, a spokesman for the American Heart Association and professor of cardiology at the University of California, Los Angeles.
For most patients, the cardiovascular benefits of regular low-dose aspirin use outweigh the potential risks, he said.
“Individuals prescribed aspirin for high-risk primary prevention or secondary cardiovascular prevention should not be concerned or discontinue this beneficial therapy,” Fonarow said.
Another expert, Dr. Sanjay Kaul, director of the Vascular Physiology and Thrombosis Research Laboratory at Cedars-Sinai Medical Center in Los Angeles, said the evidence is insufficient to know if aspirin causes age-related macular degeneration.
“Because it’s not a causal relationship, the findings [of the new study] are, at best, hypothesis,” said Kaul, co-author of an accompanying journal editorial.
For patients, the evidence supporting use of aspirin to prevent a second heart attack or stroke is “indisputable,” Kaul said. For preventing a first heart attack or stroke, the evidence of aspirin’s benefits isn’t clear and the decision of whether to take it should be based on individual risk and patient history, he noted.
People who take aspirin regularly for pain might consider switching to another painkiller to avoid possible side effects, which also include bleeding, Kaul added.
Another recent study, published in the Dec. 19 edition of the Journal of the American Medical Association, found that regular aspirin use for at least 10 years slightly raises the risk of developing age-related macular degeneration.
“Heart attacks have a high risk of death, so the question is: Is it worth the possible increase in [risk for] age-related macular degeneration, compared to the risk of getting a heart attack?” said lead researcher Dr. Barbara Klein, of the University of Wisconsin School of Medicine and Public Health.
Klein said the data from her study does not suggest that people should stop taking aspirin for preventing heart attack.