The effects of different dosages of oestrogen on the bone mineral density of postmenopausal Hong Kong Chinese women: randomised controlled trial.

OBJECTIVE: To determine the effects of different dosages of conjugated equine oestrogen on the bone mineral density of postmenopausal Hong Kong Chinese women. DESIGN: A 1-year three-arm randomised controlled trial. SETTING: Out-patient setting at a governmental hospital in Hong Kong. PARTICIPANTS: One hundred and five women aged 45 years or older, in whom menopause had occurred not more than 2 years previously. INTERVENTION: Women were assigned randomly to treatment with conjugated equine oestrogen 0.625 mg/d or 0.3 mg/d, or no oestrogen. MAIN OUTCOME MEASURE: Bone mineral density. RESULTS: Women who were assigned to the control group showed a significant reduction in bone mineral density in both the femoral neck and the lumbar spine (3.6%; P=0.001 and 4.0%; P<0.001, respectively). Those who received oestrogen 0.3 mg/d showed a significant reduction (3.9%; P=0.010) and a non-significant reduction (2.2%; P=0.141) in their lumbar spine and femoral neck bone mineral densities, respectively. In contrast, there was little change in the spinal and femoral neck bone mineral densities in women who received estrogen 0.625 mg/d. CONCLUSION: The minimum effective dosage of conjugated equine oestrogen to prevent osteoporosis in postmenopausal Hong Kong Chinese women is 0.625 mg/d. The bone mineral density, however, was maintained but not increased.