Two-year prospective and comparative study on the effects of tibolone on lipid pattern, behavior of apolipoproteins AI and B

Objective: To investigate long-term lipid and lipoprotein changes in postme nopausal women treated with tibolone in a prospective study using appropria te control groups, Design: Seventy-six of 105 postmenopausal women initially selected for this study completed the 2-year follow-up. Patients were allocated into three g roups. The first received 2.5 mg/day tibolone continuously (n = 27; group T ), the second received 0.625 mg/day conjugated equine estrogen plus 2.5 mg/ day of medroxyprogesterone (group E-P) continuously (n = 25), and a third g roup contained an additional 24 women who did not receive replacement thera py: these constituted the untreated control group (group C), Plasma lipids and lipoproteins were determined in all patients before joining the study a nd also at 12 and 24 months after being included. Results: Women treated with tibolone experienced the greatest decreases in cholesterol, both total and high density lipoprotein (HDL), and triglycerid es (TG), whereas the highest increase in HDL was observed in the group E-P A decrease in low density lipoprotein levels was detected in both therapy g roups, whereas a significant increase was observed in the control group. TG were increased after E-P therapy. in all the groups, apolipoprotein AI sho wed parallel trends to HDL and apolipoprotein B to low density lipoprotein. Conclusions: Both therapy groups, tibolone and E-P, induced changes in leve ls of plasma lipids, lipoproteins and apolipoproteins. Long-term tibolone t reatment is associated with a marked and significant decrease in HDL apolip oprotein AT and TG, an effect that defines the major difference with standa rd HRT. Clearly, further studies are necessary to establish the definite ri sk/benefit ratio of tibolone with respect to its overall effect on lipid me tabolism. (Menopause 1999,6:92-97. (C) 1999, The North American Menopause S ociety.)