January 22, 2013
Regular Aspirin Use Linked To Increased Risk Of Vision Loss In The Elderly
Connie K. Ho for redOrbit.com — Your Universe Onlinepublished in the Journal of American Medical Association (JAMA) Internal Medicine.
"The cumulative incidence of neovascular AMD among nonregular aspirin users was 0.8 percent at five years, 1.6 percent at 10 years, and 3.7 percent at 15 years; 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," remarked the authors in a prepared statement. "Regular aspirin use was significantly associated with an increased incidence of neovascular AMD."
Out of 2,389 individuals who participated in the study, 257 individuals (10.8 percent) were found to be aspirin users. In the follow-up done 15 years later, 63 individuals (24.5 percent) were discovered to have developed incident neovascular (wet) form. According to The Daily Mail, the wet form of AMD occurs when there is leaking blood vessels in the eyes. Currently, there is no preventive treatment but medications and laser surgery can help restrict the damage.
“This tells us that patients who developed wet macular degeneration were more likely to have been put on aspirin for other health reasons. Those patients who were on aspirin and those who were not on aspirin may be different in other ways and may differ in terms of other risks of wet macular degeneration such as blood pressure or cardiovascular health or even family history,” Yit Yang of the United Kingdom´s Royal College of Ophthalmologists told The Daily Mail. “It is different from saying that aspirin actually causes the development of wet macular degeneration. However it is a small signal that there could be a direct causative link but it is not possible to confirm this at present.”
The investigators believe that the decision to stop aspirin therapy is complex and based on the individual.
"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," concluded the authors in the statement.
Individual risk was also highlighted by other medical experts.
"I think a reasonable circumstance when you could ask a patient not to take aspirin might be one in which there is a very low risk of mortality from cardiovascular disease or if that person is at very great risk of losing vision from macular degeneration," stated Dr. Shawn Wilker, a physician who works at Ohio´s University Hospitals Case Medical Center, in an interview with MedPage Today.
Along with the study on aspirin therapy, JAMA Internal Medicine included a commentary on the study of aspirin use and AMD.
"This study has important strengths and limitations. It provides evidence from the largest prospective cohort with more than five years of longitudinal evaluation reported to date using objective and standardized ascertainment of AMD,” wrote Dr. Sanjay Kaul and Dr. George A. Diamond, representatives of the Cedars-Sinai Medical Center in Los Angeles, in the commentary. "The key limitation is the nonrandomized design of the study with its potential for residual (unmeasured or unobserved) confounding that cannot be mitigated by multivariate logistic regression or propensity score analysis.”
The two believe that the study could impact the general perception of aspiring use and AMD.
"From a purely science-of-medicine perspective, the strength of evidence is not sufficiently robust to be clinically directive. These findings are, at best, hypothesis-generating that should await validation in prospective randomized studies before guiding clinical practice or patient behavior," expressed the authors in the commentary. "However, from an art-of-medicine perspective, based on the limited amount of available evidence, there are some courses of action available to the thoughtful clinician. In the absence of definitive evidence regarding whether limiting aspirin exposure mitigates AMD risk, one obvious course of action is to maintain the status quo."
Medical professionals who have looked at the study believe that there is no cause for concern for individuals who take aspirin for cardiovascular benefits.
"Randomized controlled trials of aspirin use with follow-up as long as 10 years have not demonstrated any increase in the risk of age-related macular degeneration," Dr. Gregg Fonarow, a professor of medicine at the University of California, Los Angeles and a representative of the American Heart Association, told U.S. News. "Individuals prescribed aspirin for high-risk primary prevention or secondary cardiovascular prevention should not be concerned or discontinue this beneficial therapy."
Others note that there is more research needed on the subject before any recommendations are made for patients.
"Further research is needed to clarify and investigate some of the issues raised in the study; however this association may be valuable for doctors in the future when considering aspirin for their patients," said Matthew Athey of the Royal National Institute of Blind People (RNIB) in an article by BBC News.