Crandall CJ, et al. - The relationship of estrogen preparations with an index of health risks versus benefits was analyzed in this study. The current study showed that the summary index of risks versus benefits was similar for oral conjugated equine estrogen (CEE) versus oral or transdermal E₂-containing regimens. CEE + P containing less than 0.625 mg/d of CEE (vs 0.625 mg/d) for less than 5 years seemed safer.

Methods

• For this study, they used data from 45,112 participants of the Women's Health Initiative Observational Study (average follow-up 5.5 years).
• In this study, they investigated the relationship of estrogen type and oral conjugated equine estrogen (CEE) dose with time to first global index event (GIE), defined as coronary heart disease, breast cancer, stroke, pulmonary embolism, hip fracture, colorectal cancer, endometrial cancer, or death.

Results

• Oral CEE under 0.625 mg/d + progestogen (P) users had a lower risk of a GIE (adjusted hazard ratio 0.74, 95% confidence interval 0.56-0.97) than oral CEE 0.625 mg/d + P users.
• GIE risk in oral CEE 0.625 mg/d + P users was greater with not less than 5-year use (adjusted hazard ratio 1.22, 95% confidence interval 1.06-1.41) than with less than 5-year use.
• In women with prior hysterectomy, compared with women taking oral CEE 0.625 mg/d for less than 5 years, GIE risk was similar with oral CEE below 0.625 mg/d, oral estradiol (E₂), and transdermal E₂, whether used for less than 5 years or for at least 5 years.
• No difference was seen in GIE risk between users of the following: oral CEE + P versus oral E₂ + P; oral CEE + P versus transdermal E₂ + P; oral E₂ + P versus transdermal E₂ + P.
• Findings were similar among women with hysterectomy taking estrogen alone.