Long term aspirin users may be at a higher risk of developing age-related macular degeneration, which can cause blindness in old age, a new study has found.
The study, led by the University of Sydney and published in the journal JAMA Internal Medicine today, examined data on 2389 people, including regular aspirin users and non-aspirin users, over a 15 year period.
At the 15-year mark, 63 individuals out of the 2389 people had developed incident neovascular age-related macular degeneration (AMD).
“We report from this prospective population-based cohort that regular aspirin use is associated with a two-fold increase in risk of neovascular AMD during a 15-year period. These findings appear to be independent of cardiovascular disease, smoking, and other risk factors,” the authors of the study wrote.
“The cumulative incidence of neovascular AMD among nonregular aspirin users was 0.8% at five years, 1.6% at 10 years, and 3.7% at 15 years; among regular aspirin users, the cumulative incidence was 1.9% at five years, 7% at 10 years and 9.3% at 15 years, respectively.”
An accompanying commentary piece published in the same journal by Dr Sanjay Kaul and Dr George A. Diamond, both of the Cedars-Sinai Medical Centre in Los Angeles, advised a cautious interpretation of the study’s findings.
“From a purely science-of-medicine perspective, the strength of evidence is not sufficiently robust to be clinically directive,” the commentary said.
“These findings are, at best, hypothesis-generating that should await validation in prospective randomised studies before guiding clinical practice or patient behaviour.”
Professor John McNeil, head of the Monash University Department of Epidemiology and Preventive Medicine and Co-chief investigator of the ASPREE study into the benefits and risks of aspirin, said any observational study should be taken with a grain of salt.
“The relationship between aspirin and AMD is very complex,” said Professor McNeil, who was not involved in the University of Sydney study published today in JAMA Internal Medicine.
“In the early stage, it may prevent it but in the late stage it may cause bleeding. We need proper clinical trials to sort this out,” he said, adding that the National Health and Medical Research Council was funding a clinical trial that was expected to deliver results by about 2018.
“That will provide a much more definitive answer.”
Professor Christopher Reid, also from Monash University’s Department of Epidemiology and Preventative Medicine said the study published in JAMA Internal Medicine today was well conducted but was of a relatively small number of people and non-randomised.
“Dose of aspirin and length of exposure to aspirin are also not particularly well collected. The authors and also the attached commentary emphasise the importance of not over interpreting these findings as there are many factors (unmeasured) in observational studies that may influence the outcomes reported,” he said.
“It is too early and there is not sufficient data to try to relate these findings into clinical practice. Those who are concerned should discuss with their doctor, however observational study findings should not change patient treatment nor clinical practice.”