HealthDay News — Using aspirin long term may raise the risk of developing late age-related macular degeneration, results from a longitudinal cohort study suggest.
Regular aspirin use over a 10-year period was associated with a 63% increased risk of late AMD (P=0.05), Barbara E.K. Klein, MD, MPH, from the University of Wisconsin School of Medicine and Public Health in Madison, and colleagues reported in the Journal of the American Medical Association.
No increased risk for either early or late AMD was observed with five-year aspirin use, the researchers noted.
About 20% of U.S. adults use aspirin on a regular basis, but previous studies assessing the relationship between the drug and AMD have been inconclusive. So Klein and colleagues assessed aspirin use and AMD onset in the Beaver Dam Eye Study, which involved 4,926 participants aged 43 to 86 years at baseline. Examinations were performed every five years over a 20-year period.
Patients were asked if they had regularly used aspirin at least twice a week for more than 3 months. The main outcomes measures were early AMD, late AMD, and two subtypes of late AMD — neovascular AMD and pure geographic atrophy.
Over a 14.8 years median follow-up period, the researchers identified 512 incident cases of early AMD and 117 incident cases of late AMD.
They found that regular aspirin use 10 years prior to the retinal examination was associated with a greater risk of late AMD (hazard ratio 1.63; 95% CI: 1.01-2.63).
The estimated incidence of late AMD was 1.76% (95% CI 1.17% to 2.64%) in regular aspirin users compared with 1.03% (95% CI: 0.70%-1.51%) in non-users. Among patients reporting five-year aspirin use the incidence of late AMD was numerically higher, but the finding was not statistically significant.
Among AMD subtypes, regular aspirin use 10 years before retinal examination correlated significantly with neovascular AMD (hazard ratio, 2.20; 95% CI:1.20-4.15; P=0.01) but not with pure geographic atrophy (HR, 0.66; 95% CI: 0.25-1.95; P=0.45). There was no correlation for aspirin use at five or 10 years before retinal examination and early AMD.
In further analyses, the researchers found no relationship between long-term, 10-year use of any nonsteroidal anti-inflammatory drugs or warfarin and the risk of AMD.
“Our findings are consistent with a small but statistically significant association between regular aspirin use and incidence of neovascular AMD,” the researchers wrote. “If confirmed, defining the causal mechanisms may be important in developing methods to block this effect to prevent or retard the development of neovascular AMD in persons who use aspirin, especially to prevent cardiovascular disease.”