Racial Differences in the Effects of Hormone Therapy on Incident Open-Angle Glaucoma in a Randomized Trial.

Abstract

We conducted a secondary analysis of a randomized, placebo-controlled trial to test if hormone therapy (HT) altered the risk of open-angle glaucoma (OAG), and if the risk reduction varied by race. Secondary analysis of randomized controlled trial data. We linked Medicare claims data to 25 535 women in the Women's Health Initiative. Women without a uterus were randomized to receive either oral conjugated equine estrogens (CEE 0.625 mg/day) or placebo, and women with a uterus received oral CEE and medroxyprogesterone acetate (CEE 0.625 mg/day + MPA 2.5 mg/day) or placebo. We used Cox proportional hazards models to calculate hazard ratios (HR) and 95% confidence interval. After exclusion of women with prevalent glaucoma or without claims for eye care provider visits, the final analysis included 8102 women (mean age = 68.5 ± 4.8 years). The OAG incidence was 7.6% (mean follow-up = 11.5 ± 5.2 years; mean HT duration = 4.4 ± 2.3 years). Increased age (P trend = .01) and African-American race (HR = 2.69, 95% CI = 2.13-3.42; white as a reference) were significant risk factors for incident OAG. We found no overall benefit of HT in reducing incident OAG (HR = 1.01, 95% CI = 0.79-1.29 in the CEE trial, and HR = 1.05, 95% CI = 0.85-1.29 in the CEE + MPA trial). However, race modified the relationship between CEE use and OAG risk (P interaction = .01), and risk was reduced in African-American women treated with CEE (HR = 0.49, 95% CI = 0.27-0.88), compared to placebo. Race did not modify the relation between CEE + MPA use and OAG risk (P interaction = .68). Analysis suggests that HT containing estrogen, but not a combination of estrogen and progesterone, reduces the risk of incident OAG among African-American women. Further investigation is needed.