Efficacy of tibolone and raloxifene for the maintenance of skeletal muscle strength, bone mineral density, balance, body composition, cognitive function, mood/depression, anxiety and quality of life/well-being in late postmenopausal women >/= 70 years: study design of a randomized, double-blind, double-dummy, placebo-controlled, single-center trial.

Background: Postmenopausal women are prone to develop functional disabilities as a result of reduction in muscle strength and muscle mass caused by diminished levels of female sex hormones. While hormone replacement therapy may counteract these changes, conventional hormone replacement therapy is associated with potential harmful effects, such as an increased risk of breast cancer, and its prescription is not recommended. For this reason newer alternative drugs, such as tibolone, a synthetic steroid with estrogenic, progestogenic and androgenic activity, and raloxifene, a selective estrogen receptor modulator, may be more appropriate. This trial investigates the effect of tibolone and raloxifene on muscle strength.

Methods: We recruited 318 elderly women in our single-center randomized, double-blind, double-dummy, placebo-controlled trial. Participants were randomized to tibolone 1.25 mg (Org OD 14, Organon NV, the Netherlands) plus placebo, raloxifene 60 mg (Evista(R), Eli Lilly, United States) plus placebo or two placebo tablets daily for 24 months.The primary aim is to determine if there is a difference between tibolone and placebo or if there is a difference between raloxifene and placebo. Primary endpoints are muscle strength and bone mineral density. The secondary endpoints are postural balance, body composition, cognitive function, anxiety, mood and quality of life. The secondary aim is to determine if there is a difference between tibolone and raloxifene. The measure of effect is the change from the baseline visit to the visits after 3 months, 6 months, 12 months, and 24 months. A follow-up measurement is planned at 30 months to determine whether any effects are sustained after cessation of the study. By December 2007 the blind will be broken and the data analyzed.

Trial Registration Number: NTR: 1232.