Prevention of Postmenopausal Bone Loss at Lumbar Spine and Upper Femur With Tibolone: A Two-Year Randomised Controlled Trial

Abstract

Objective To examine the effects of tibolone on bone mineral density and its concurrent safety and subject acceptability. Design Prospective randomised controlled study. Setting Centre for Metabolic Bone Disease, Hull. Population Forty-seven healthy post-menopausal women aged 50–57 years with normal bone mineral density at lumbar spine. Methods Bone mineral density was assessed every 24 weeks at lumbar spine and proximal femur using dual energy X-ray absorptiometry. Results The bone mineral density of the tibolone treated subjects tended to increase while those of the controls tended to fall. The higher densities in the tibolone group were significant at lumbar spine from week 24 (P= 0.002) and at the trochanter from week 72 (P= 0.014). The lower bone densities in the controls were significant at Ward's Triangle and femoral neck at week 96 (P < 0.0001), and at lumbar spine from week 24 onwards (P < 0.05). Between-treatment analysis indicated that, by the 96th week, the bone densities at all sites in the tibolone group were significantly different from those in the control group. At the lumbar spine the differences were highly significant throughout the study (P < 0.0004). Four women receiving tibolone withdrew from the study due to unacceptable adverse events. Two women withdrew from the control group. There was no significant difference between the groups in the number of subjects suffering adverse experiences. Vaginal bleeding occurred in seven women, all from the tibolone treated group, resulting in one withdrawal from the study. Conclusion Tibolone is thus an effective and well-tolerated alternative to oestrogen in the prevention of osteoporosis with its beneficial effects being most apparent at the lumbar spine.