Abstract [from journal]
Importance: Oral contraceptives have been associated with cardiovascular disease, ischemic stroke, venous thromboembolic disease, and breast cancer. Retinal vascular occlusions share the same risk factors as cardiovascular and cerebrovascular disease.
Objective: To determine whether filling a prescription of female hormone therapy (FHT) is associated with an increased risk of retinal artery occlusion (RAO) or retinal vein occlusions (RVO).
Design, setting, and participants: A multiple-cohort study was conducted using an administrative claims insurance database comparing women who filled a prescription for FHT with matched control individuals. Exclusion occurred for those enrolled for less than 2 years in the plan, with no prior ophthalmologic examination, with a history of a RAO/RVO, with systemic diseases/medications that affected estrogen levels, or a disease associated with an increased risk for thromboembolism.
Main outcomes and measures: The primary outcome was the incidence of a new diagnosis of RAO or RVO. Cox proportional hazard regression modeling with inverse probability of treatment weight was used to assess the hazard ratio (HR) for a new diagnosis of RAO or RVO relative to filling prescription for FHT. Subanalyses were conducted to stratify by age, race/ethnicity, diabetes, and hypertension.
Results: A total of 205 304 women who filled a prescription for FHT were matched to 755 462 control individuals. After inverse probability of treatment weight, the study cohort was a mean age of 47.2 years, 71% were White, 7% were Black, 6% were Hispanic, 3% were Asian, and 3% were unknown. There were 41 cases (0.01%) of RAO and 68 cases of RVO (0.02%) in the FHT cohort. In comparison, there were 373 cases of RAO (0.05%) and 617 cases of RVO (0.08%) in the control cohort. After inverse probability of treatment weight, Cox regression analysis showed no difference in hazard for RAO, RVO, or combined outcomes in the FHT cohort relative to the control cohort (RAO HR, 1.17; 95% CI, 0.83-1.65; P = .36; RVO HR, 1.07; 95% CI, 0.82-1.39; P = .65; combined HR, 1.10; 95% CI, 0.89-1.36; P = .37). Subanalyses that stratified by age, diabetes, and hypertension similarly showed no significant associations between the FHT prescription cohort and all outcomes.
Conclusions and relevance: These findings suggest that filling a prescription for FHT, and presumably taking FHT, does not increase the risk of RAO or RVO. Such history may not be relevant in the evaluation of an individual with an RAO or RVO nor do our results support stopping FHT in an individual who develops an RAO or RVO.