A 5-year study on the effect of hormone therapy, tibolone and raloxifene on vaginal bleeding and endometrial thickness

Abstract

Objectives To study the effect of standard and low-dose estrogen–progestin therapy (EPT), tibolone and raloxifene on the incidence of vaginal spotting/bleeding and endometrial thickness over a 5-year period. Methods Seven hundred eighty-six postmenopausal women were studied in an open prospective design. Vaginal spotting/bleeding and endometrial thickness as assessed by transvaginal ultrasonography was compared between six categories of women over a 5-year period: three categories in women on continuous combined estrogen–progestin therapy, one category under tibolone, one category under raloxifene and one under no treatment. More specifically, women received tibolone 2.5 mg ( N = 204), raloxifene HCl 60 mg ( N = 137), conjugated equine estrogens 0.625 mg/medroxyprogesterone acetate 5 mg ( N = 122), 17β-estradiol 2 mg/norethisterone acetate 1 mg ( N = 58), 17β-estradiol 1 mg/norethisterone acetate 0.5 mg ( N = 76) or no therapy (controls, N = 189). Women with suspected endometrial pathology were referred for hysteroscopy. Results Bleeding/spotting incidence was highest among standard dose EPT users (conjugated equine estrogens 0.625 mg/medroxyprogesterone acetate 5 mg: 40.1%, 17β-estradiol 2 mg/norethisterone acetate 1 mg: 44.8%, p < 0.001 compared to controls). Low-dose EPT associated with lower incidence of spotting/bleeding (34.1%). The incidence under tibolone and raloxifene was 22.5% and 2.9%, respectively, while 3.2% of women not receiving therapy reported vaginal spotting/bleeding. Mean endometrial thickness was not significantly affected in any of the groups studied. The drop-out rate due to spotting/bleeding was higher in the two higher dose EPT regimens. After logistic regression analysis, age at baseline was the only significant predictor of subsequent spotting/bleeding ( b = −0.25, S.E. = 0.09, p = 0.006), while menopausal age and pre-treatment serum FSH had marginal significance. Conclusions EPT, tibolone and raloxifene do not appear to associate with significant changes in endometrial thickness in the majority of cases. The low-dose EPT regimen associated with a decreased incidence of unscheduled spotting/bleeding compared to the standard dose regimens. Tibolone expressed a favorable endometrial profile, as seen in its effect on unscheduled spotting/bleeding and mean endometrial thickness. Raloxifene associated with the lowest incidence in S/B and the lowest drop-out rate.s