Bone mineral density and age-related maculopathy in older women

OBJECTIVES: To determine whether bone mineral density (BMD) is associated with age-related maculopathy (ARM) risk in older women. DESIGN: Cross-sectional analysis at Year 10 (1997/98) of the Study of Osteoporotic Fractures (SOF). SETTING: Four clinical centers in the United States. PARTICIPANTS: One thousand forty-two randomly sampled SOF participants who attended the Year 10 clinic visit. MEASUREMENTS: ARM status was determined from fundus photographs using a modification of the Wisconsin Age-Related Maculopathy Grading System 6-level severity scale used in the National Health and Nutrition Examination Survey III. Total hip BMD was measured at Year 10 using dual-energy x-ray absorptiometry. Information on potential confounders, including age, reproductive hormone exposures, body mass index, smoking, alcohol consumption, nutrition, education, diabetes mellitus, hypertension, and physical activity, was ascertained with questionnaires. RESULTS: The prevalence of ARM was 50% (46% had early ARM and 4% had late ARM). After potential confounder adjustment, greater BMD was associated with lower odds of ARM (odds ratio (OR) per 1 standard deviation increase in BMD=0.82, 95% confidence interval (CI)=0.70-0.96). Women in the highest quartile of BMD had lower odds of ARM than those in the lowest quartile (OR=0.63, 95% CI=0.41-0.97) and those in the lowest three quartiles combined (OR=0.66, 95% CI=0.48-0.91). CONCLUSION: Higher levels of BMD may be associated with lower risk for ARM. The underlying mechanism is unknown, although BMD may be a marker for lifetime endogenous estrogen exposure. Future studies are needed to replicate these findings and further investigate the nature of the relationship between BMD and ARM.