The Women's Health Initiative: Hormone Therapy and Calcium/Vitamin D supplementation trials.

The Women's Health Initiative (WHI) was a large and complex study focused on strategies for the prevention and control of common chronic diseases of postmenopausal women. The WHI included 3 randomized controlled trials: the Hormone Therapy (HT) Trials, the Diet Modification Trial, and the Calcium/Vitamin D (CaD) Trial. Conjugated equine estrogen with or without a progestin significantly decreased hip, clinical vertebral, and all fractures. Once the intervention was stopped, the fracture benefit dissipated. However, estrogen plus progestin was associated with more risks than benefits and use of hormone therapy solely for the prevention of osteoporosis is not recommended. The CaD trial found no overall benefit for fracture reduction except in adherent women and women taking supplements for 5 or more years. Overall, the common practice of taking calcium and vitamin D supplementation with possible benefits on hip and positive evidence on bone mineral density and few risks is reasonable.