Using aspirin regularly in hope of preventing recurrent cardiovascular problems may increase an individual’s risk of developing macular degeneration, a leading cause of vision loss, according to a new study published in JAMA Internal Medicine.
Many individuals who have had a heart attack or stroke take aspirin regularly because it has been shown to reduce the risk of a recurrence of these cardiovascular disease (CVD) events. But as with all medications, regular aspirin use is associated with some risks, the most well established of which include bleeding in the stomach or around the brain. One previous study of a cross-section of 4691 older Europeans found an increased risk of macular degeneration among regular aspirin users (Ophthalmology. 2011;119:112-118). But the finding generated controversy because this kind of study alone can’t prove that aspirin contributes to macular degeneration.
So Jie Jin Wang, PhD, of the Centre for Vision Research at the University of Sydney, Australia; Paul Mitchell, PhD, also of Centre for Vision Research; and colleagues analyzed data on 2389 individuals. The individuals were enrolled in a prospective study of eye health among older Australians, the Blue Mountains Eye Study, led by Mitchell. Incidence of neovascular AMD among aspirin users over 15 years was 9.3% compared with 3.7% of nonusers.
Dr Wang and Dr Mitchell discussed the findings with news@JAMA via e-mail.
news@JAMA: How does your study advance our understanding of the relationship between aspirin use and AMD?
Dr Wang: Our finding of a longitudinal association confirms an observation from the European cross-sectional survey that also reported a 2-fold higher prevalence of neovascular AMD among regular aspirin users compared with nonusers. This confirmation suggests a consistency of the evidence on this association in 2 different population-based samples.
news@JAMA: Does it resolve the controversy?
Dr Wang: Evidence from observational studies can usually only generate and/or support a study hypothesis but cannot resolve completely the controversy of the study hypothesis, mainly due to the lack of a proven mechanism for the association.
news@JAMA: What do you think are the implications of your findings for the use of aspirin to prevent recurrent heart attacks or strokes?
Dr Mitchell: While aspirin is among the most effective CVD preventive therapies to reduce recurrent CVD events, regular use over the longer term has been associated with a number of well-documented adverse effects. The possibility of an effect on vision via an increase in the risk of AMD needs to now also be considered, in addition to other adverse effects, such as increased gastrointestinal, intracerebral, and extracranial hemorrhage.
Given the widespread use of aspirin, any increased risk of disabling conditions and morbidity would likely be important and may affect small subgroups of patients—in this case, patients who are at high risk of neovascular AMD. However, the magnitude of this potential risk is relatively small and needs to be balanced with the significant morbidity and mortality of suboptimally treated cardiovascular disease.
news@JAMA: Should physicians rethink the way they use aspirin?
Dr Mitchell: Currently there is insufficient evidence to recommend changing clinical practice, except in cases of patients with strong risk factors for neovascular AMD. If patients have a strong family history of neovascular AMD or have late AMD already affecting 1 eye, physicians could raise the awareness in patients and their families about the possibility of this possible adverse effect following long-term use of aspirin. Confirmation of our study findings in other longitudinal studies, however, will also be very important.
news@JAMA: What other studies are needed to further clarify the relationship between AMD and aspirin?
Dr Wang: Experimental studies in animal models are needed to explain the underlying mechanism for this association—or studies in humans using randomized controlled trials, where feasible. For example, randomized controlled trials to test the effect of aspirin on other health outcomes could also collect information about vision and the retina of the eye to assess possible adverse effects on vision and the eye.