Endometrial and vaginal effects of low-dose estradiol delivered by vaginal ring or vaginal tablet.

Aims: The major aims of the study were to compare the safety of a continuous low-dose estradiol-releasing vaginal ring (ESTring) to that of a vaginal estradiol tablet (Vagifem) on the endometrium and the relief of subjective symptoms and signs of urogenital estrogen deficiency. Quality of life and acceptability of treatment delivery were also assessed.

Study Design: A prospective, randomized study in which women were assigned in a 2:1 ratio to ESTring and Vagifem and followed for 12 months. The primary endpoint was endometrial safety, based on the results of ultrasound measurement of endometrial thickness and a progestogen challenge test at baseline and week 48. Efficacy was determined by subjective assessment of urogenital estrogen deficiency symptoms at baseline and weeks 3, 12, 24, 36 and 48 and assessment of signs of vaginal epithelial atrophy by the clinician at baseline, 12 and 48 weeks. In addition, pelvic floor strength, vaginal cytological evaluation and pH, bacteruria and patient acceptability were assessed. Quality of life was assessed using a menopause-specific quality-of-life questionnaire and a 2-day bladder diary at baseline and 12 and 48 weeks. The comparability of the two groups was assessed using ANOVA, chi2 or Fisher's exact tests.

Results: A total of 126 women were randomized to ESTring and 59 to Vagifem. There was no statistical difference between the groups in the alleviation of symptoms and signs of urogenital estrogen deficiency. Maturation indices increased in both groups, from generally atrophic at baseline to proliferative or highly proliferative at 48 weeks. After 48 weeks of treatment, there was no statistically significant difference in endometrial thickness between the two groups. A statistically smaller proportion of bleeding/spotting occurred in the ESTring group (n = 0) compared to the Vagifem users (n = 4). Estradiol and total estrone serum levels increased during treatment in both groups but remained within the normal postmenopausal range. General health status in both groups was unchanged but the urogenital component of health burden was significantly improved in both groups. Bladder diary variables showed no differences between treatment groups.

Conclusion: Equivalent endometrial safety and efficacy in the relief of the symptoms and signs of urogenital estrogen deficiency were demonstrated for the 12 months' use of a low-dose estradiol-releasing vaginal ring and a vaginal estradiol tablet.