The incidence of vaginal bleeding with tibolone treatment

Abstract

To determine the incidence of breakthrough bleeding and its significance in recently postmenopausal women who take tibolone (Livial-Organon). A two year comparative nonrandomised prospective study of women taking tibolone (2.5 mg) and control subjects not on medication. Teaching hospital menopause and well women clinic. One hundred women who were recently menopausal (between 6 and 36 months since last menstrual period). Fifty were commenced on tibolone and 50 received no medication. Episodes of bleeding throughout the two year study period were recorded. Oestradiol levels were measured at baseline and at six, 12 and 24 months. The age of menopause and time since last menstrual period (LMP) were noted. Twenty percent (12/59) (95% CI 11.0% to 32.8%) of women in the tibolone group had breakthrough bleeding compared with 9.4% (5/23) (95% CI 3.1% to 20.7%) in the control group. Of the women who bled in the tibolone group, 50% had LMP between six and 12 months prior to entering the study, and 83% were younger than the average age of menopause. Sixty-seven percent had detectable oestradiol levels on at least one occasion over the two years (five women had detectable oestradiol levels and did not bleed). None had evidence of endometrial stimulation at dilatation and curettage. Eighty percent of women who bled in the control group were between six and 12 months since LMP on entry into the study, and 80% had detectable oestradiol levels during the study. At dilatation and curettage there was no evidence of endometrial stimulation. A minority of women will bleed on tibolone therapy. Women who are likely to bleed are younger, are recently menopausal, and may have remaining endogenous oestrogen production.