Long term effects of tibolone on the genital tract in postmenopausal women

Objectives To assess the effects of six years tibolone therapy on the genit al tract in postmenopausal women against matched voluntary controls. Design Prospective, non-randomised, open label study of the efficacy of tib olone. Methods Symptoms were assessed by questionnaires every six months. Assessme nt of genital tract cellular activity comprised annual vaginal smear and en dometrial biopsy/smear in the tibolone group (n = 58) and vaginal smear alo ne in the control group (n = 55). As a recent protocol addition, transvagin al ultrasound assessment of endometrial thickness was performed in all wome n who gave consent. Endometrial biopsy was performed in control women if th e endometrial thickness was > 5 mm. Karyopyknotic index and maturation inde x were calculated from the vaginal smears. Results The rate of amenorrhoea between six months and six years treatment was 90% in the tibolone group compared with 91% in the controls (P was not significant). There was improvement in reported vaginal symptomatology in t he treatment group but not in the controls. Median endometrial thickness in creased slightly in the tibolone treated group (3.2 mm tibolone vs 2.5 mm c ontrol; P < 0.05). There were no cases of cytologically proven endometrial stimulation in asymptomatic women in either group. Both vaginal karyopyknot ic index and maturation index increased significantly in the tibolone treat ed group over six years, but not in the control group. Conclusions Tibolone is effective at maintaining an inactive endometrium wh ile providing oestrogenisation of the lower genital tract over a six year p eriod.