TUESDAY, Dec. 18, 2012 (HealthDay News) -- People who use aspirin regularly for at least 10 years run a small risk of developing a potentially blinding condition known as age-related macular degeneration, researchers report.
In the United States, an estimated 19 percent of adults report using aspirin regularly and aspirin use increases with age, the University of Wisconsin researchers noted. Meanwhile, the incidence of age-related macular degeneration is increasing as the population ages, making this association important to examine, they added.
"There are a lot of people taking aspirin for cardioprotection," said lead researcher Dr. Barbara Klein, from the university's School of Medicine and Public Health.
"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?" she said.
"These data do not suggest that people should stop taking aspirin for cardioprophylaxis," Klein said. "One should not alter aspirin use based on these findings."
The report was published in the Dec. 19 edition of the Journal of the American Medical Association.
For the study, Klein's team collected data on almost 5,000 men and women who took part in the Beaver Dam Eye Study. Participants had their eyes checked every five years over a 20-year period. In addition, they were asked about their use of aspirin.
Over almost 15 years of follow-up, 512 people developed early macular degeneration and 117 people developed late macular degeneration.
The investigators found that people who took aspirin for 10 years almost doubled their risk for developing macular degeneration, compared with a less than 1 percent risk among people who did not take aspirin.
When the researchers looked specifically at late age-related macular degeneration, they found aspirin users had a 1.4 percent increased risk of developing the condition, compared with a 0.6 percent risk among those who did not take aspirin.
These findings show an association between age-related macular degeneration and aspirin use, and not a cause-and-effect relationship.
Klein noted that the biological mechanism for this association isn't known. If it turns out that there is one, then it might lead to new ways to protect people from heart attacks and strokes, she said.
One expert cautioned that it is too soon to change clinical practice.
"While this observational study suggests there may be an association of long-term aspirin use with age-related macular degeneration, the potential risk was small in absolute terms, [and] the association may not be causal," said Dr. Gregg Fonarow, a professor of cardiology at the University of California, Los Angeles.
Moreover, randomized controlled trials of aspirin use with follow-up as long as 10 years have not shown any increase in the risk of age-related macular degeneration, he said. A randomized, controlled study is one in which people are randomly assigned to different groups: one group receives the treatment and the other does not receive the treatment (the "control" group).
"For most patients, the benefits of regular low-dose aspirin use outweigh the potential risks," Fonarow said. "Individuals prescribed aspirin for primary or secondary cardiovascular prevention should not be concerned or discontinue this beneficial therapy."
For more on aspirin and heart disease, visit the American Heart Association.