Long-Term Effects of Continuous Combined HRT on Bone Turnover and Lipid Metabolism in Postmenopausal Women

Abstract:

This study was undertaken to investigate the effect of 10 years of hormone replacement therapy (HRT) on bone turnover and lipid metabolism in postmenopausal women. The single-centre trial was initiated as a 1-year, double-masked, randomized, parallel-group study of continuous combined HRT with 2 mg 17b-estradiol and 1 mg norethisterone acetate administered once daily with or without 1 mg estriol. Following preliminary results which showed no difference between the addition and omission of estriol, patients continued on an open-label extension phase of continuous combined HRT without estriol for a further 9 years. Of the 52 women who entered the original double-masked study, 32 entered the open-label extension phase. The 10-year analysis was based on 27 patients. Major increases in bone mineral density (BMD) of the lumbar spine were seen during the first 3 years of treatment, remaining statistically significant compared with baseline at all visits throughout the 10-year follow-up (p40.025). Statistical modelling confirmed that there were no decreases in BMD after these initial increases. BMD remained 5.5% higher than baseline values after 10 years of continuous combined HRT. Mean total cholesterol levels were significantly reduced after 10 years of therapy (p= 0.012), with no significant changes in serum triglyceride and low-density lipoprotein (LDL)-cholesterol levels from baseline values at this time. High-density lipoprotein (HDL)-cholesterol levels, however, were reduced by 15.4% (p50.001). In conclusion, 10 years of continuous combined HRT resulted in a significant and sustained increase in BMD. This treatment regimen therefore appears to be well suited for the long-term prevention of osteoporosis in postmenopausal women.