Researchers at the Centre for Vision Research, Westmead Millennium Institute for Medical Research (WMI) in Sydney have announced today (22 January 2013) their findings that regular aspirin consumption is associated with an increased risk of neovascular age-related macular degeneration (AMD) - a leading cause of blindness in older people.
The research, published in the journal JAMA Internal Medicine, shows that the risk appears to be independent of a history of smoking, which is also a known preventable risk factor for AMD.
Aspirin is one of the most widely used medications in the world with more than 100 billion tablets consumed each year. Aspirin is commonly used in the prevention of cardiovascular disease, such as myocardial infarction (heart attack) and ischemic stroke.
While a five-year European study published last year suggested that regular aspirin use (defined as once or more per week in the past year) was associated with AMD, other studies had reported inconsistent findings.
The study by the Centre for Vision Research's Gerald Liew, PhD, and colleagues was conducted over a much longer period and found clear evidence of the risk.
They conducted a prospective analysis of data from an Australian study (the Blue Mountains Eye Study) that included four examinations during a 15-year period.
Of 2,389 participants, 257 individuals (10.8 percent) were regular aspirin users.
After the 15-year follow-up, 63 individuals developed incident neovascular AMD, according to the results.
"The cumulative incidence of neovascular AMD among non regular aspirin users was 0.8 percent at five years, 1.6 percent at 10 years, and 3.7 percent at 15 years," said the director of WMI's Centre for Vision Research, Professor Paul Mitchell.
"Among regular aspirin users, the cumulative incidence was 1.9 percent at five years, 7 percent at 10 years and 9.3 percent at 15 years, respectively, indicating that regular aspirin use is significantly associated with an increased incidence of neovascular AMD. This increase was around 2.5-fold, after accounting for potentially confounding variables."
WMI report's authors note that any decision concerning whether to stop aspirin therapy is "complex and needs to be individualised."
"Currently, there is insufficient evidence to recommend changing clinical practice, except perhaps in patients with strong risk factors for neovascular AMD (e.g., existing late AMD in the fellow eye) in whom it may be appropriate to raise the potentially small risk of incident neovascular AMD with long-term aspirin therapy," the authors conclude.
Julie Heraghty, CEO of the Macular Degeneration Foundation welcomes these research findings but cautions that we need more studies to see if the finding is consistent.
"This is the strongest lead yet on the relationship between the long-term use of aspirin and wet age-related macular degeneration. However, it is still not enough evidence to show a causal link," she said.
"Research has highlighted this relationship between long-term regular use of aspirin and wet age-related macular degeneration and it is research which will finally give us the definitive answer."
"In Professor Paul Mitchell we are fortunate in Australia to have one of the world leading experts in this field and we need to fund this type of research to find more reasons and answers to this devastating disease," she said.
Note: Professor Mitchell was an inaugural recipient of the Macular Degeneration Foundation Research Grants program in 2011, for a separate project.
22 January 2013