Hormone replacement therapy: effect of progestin dose and time since menopause on endometrial bleeding

To analyze the effects of two continuous combined hormone replacement regimens on bleeding profiles in postmenopausal women, based on progestin dose and time since the patient's last spontaneous menstrual period.

A randomized, double-masked, multicenter trial was conducted in 1724 women recruited from 99 sites. Six hundred seventy-eight women received a continuous regimen of oral conjugated equine estrogens (CEE), 0.625 mg/day, combined with medroxyprogesterone acetate (MPA), 2.5 or 5.0 mg/day, for 1 year.

After 1 year, no bleeding was reported by over 89% of women. More women in the 5.0 mg/day MPA group than in the 2.5 mg/day MPA group reported no bleeding (93.8% versus 89.5%; P<.089). Of those women who had had their last menstrual period 3 years ago or less, a significantly higher percentage in the 5.0 mg/day MPA group (72.4%) did not experience bleeding after three cycles compared with the 2.5 mg group (59.0%; P<.001). Although the percentage of patients without bleeding was also higher in the 5.0 mg/day MPA group after six cycles and 1 year, the differences between groups were not statistically significant. Of the women who had their last menstrual period more than 3 years ago, 94.7% of those in the 5.0 mg/day MPA group and 90.7% of those in the 2.5 mg/day MPA group reported no bleeding at 1 year.

A continuous combined regimen of CEE plus 5.0 mg MPA may be more suitable for women closer to the onset of menopause or for women starting therapy who are unwilling to tolerate irregular bleeding. The improved bleeding profile with CEE and 5.0 mg/day MPA is likely to enhance compliance with hormone replacement therapy.