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This week the results of a research study looking at the risk of aspirin use and the development of wet age-related macular degeneration (AMD) was published in the journal, JAMA Internal Medicine. This is a very important topic as many elderly people use aspirin on a daily basis (e.g. to reduce the risk of heart attacks and strokes) and AMD is the number one cause of blindness in the elderly population of western countries, like Australia and the US. There are two forms of the disease, a dry (non-exudative) form and a wet (exudative) form. Wet AMD can lead to rapid vision loss and blindness if not properly treated in a timely manner.
The study looked at 2389 Australians during a 15-year period (1992-1994 to 2007-2009). In that time 257 (10.8%) were regular aspirin users and 63 (24.5%) developed wet AMD.
The authors found that aspirin users had a 9.3% incidence of wet AMD, compared to 3.7% in nonusers. This resulted in an odds ratio of 2.46 for developing wet AMD with aspirin use. Also, the more frequently someone used aspirin, the more likely they were to develop wet AMD (2.2% in those who never took aspirin, 2.9% for those who used it only occasionally, and 5.8% for those who took aspirin routinely). Lastly, aspirin use was not associated with risk for the advanced form of dry AMD (called geographic atrophy).
What does this mean?
While this one study showed a correlation between aspirin use and the development of wet AMD, correlation does not imply causation. There could have been other associated factors that the researchers did not uncover that was related to the development of wet AMD. It’s too early to jump the gun and recommend that our elderly patients stop taking aspirin if they are at risk for wet AMD. There could be many ill consequences to stopping aspirin, like increased strokes and heart attacks, so changing aspirin use recommendations should not be taken lightly.
Also, in Australia, the average aspirin dose is 150 mg, while it is 81 mg in the US. It is unclear whether the dose of aspirin is related to the risk of developing wet AMD, as the researchers in the study did not look at different doses. It could turn out that the American 81 mg dose does not increase the risk of developing wet AMD.
The bottom line is that it is too early to make any recommendations on the use of aspirin in patients with AMD. Further research is needed to delineate the relationship of aspirin to to AMD.