Bleeding patterns and endometrial histology during administration of low-dose estradiol sequentially combined with dydrogesterone

Abstract

Objective: To determine bleeding patterns and endometrial response in postmenopausal women taking low-dose (1 mg) estradiol in a sequential combined formulation with 5 or 10 mg dydrogesterone.

Methods: A total of 151 postmenopausal women were allocated randomly to 5 or 10 mg dydrogesterone during cycle days 15-28 in a sequential oral formulation with 1 mg estradiol continuously during 13 cycles of 28 days. Occurrence of vaginal bleeding was recorded daily and analyzed in accordance with World Health Organization (WHO) standards. Endometrial biopsies, obtained at baseline and cycle days 25-27 of the final treatment cycle, were interpreted independently by two pathologists.

Results: The study was completed by 131 women (87%). The percentage of women with bleeding (mean +/- SD) was 57.2 +/- 3.6% in the 1/5-mg group and 65.8 +/- 4.2% in the 1/10-mg group (p < 0.001); cross-sectional analysis showed that, in every cycle, there were more women with bleeding in the 1/10-than in the 1/5-mg group (p < 0.001). With regard to the day of onset of bleeding, the mean difference between groups was 1.4 +/- 1.1 days (p < 0.001). There was no difference in duration of bleed (5 days), or intensity or incidence of intermittent bleeding (3-14% per cycle). Both regimens resulted in high rates of amenorrhea in each cycle (26-49%), but only 14/151 (9%) women were amenorrheic throughout. Three patients (2%) discontinued owing to bleeding problems. Endometrial protection was adequate in 98.3% (1/5-mg group) and 98.5% (1/10-mg group) with only one case of proliferation (1/10-mg group) and one of simple hyperplasia (1/5-mg group).

Conclusions: The bleeding pattern associated with low-dose (1 mg) estradiol sequentially combined with 5 or 10 mg dydrogesterone shows a high rate of amenorrhea in each cycle; there is a dydrogesterone dose effect on the occurrence and day of onset of bleeding. Bleeding episodes that occur show a regular pattern and are of slight intensity. The endometrial safety of both regimens is high.