Felson D T, Zhang Y, Hannan M T, Kiel D P, Wilson P W, Anderson J J
Boston University Arthritis Center, MA.
N Engl J Med. 1993 Oct 14;329(16):1141-6. doi: 10.1056/NEJM199310143291601.
Estrogen therapy prevents bone loss in postmenopausal women who take it early in the postmenopausal period. The risk of fracture is highest much later in life, however. We studied whether bone mass in elderly women was affected by earlier estrogen use and how long women needed to take estrogen for it to have a beneficial effect on bone density later in life.
In 1988 and 1989, we measured bone mineral density at the femur, spine, shaft of the radius, and ultradistal radius in 670 white women in the Framingham Study cohort (mean age, 76 years; range, 68 to 96). These women had been followed prospectively through menopause and had been asked repeatedly about estrogen therapy. After excluding women who began taking estrogen after a fracture, we investigated whether postmenopausal estrogen therapy affected bone density; in these analyses we adjusted for age, weight, height, cigarette smoking, physical activity, and age at menopause.
A total of 212 women (31.6 percent) had received estrogen therapy (mean estimated duration of treatment, 5 years). Only women who had taken estrogen for 7 to 9 years or for 10 or more years had significantly higher bone mineral density than women who had not taken estrogen (7 to 9 years of treatment, P < 0.05 at sites in the femur and the spine; > or = 10 years, P < 0.05 at all sites except the spine). In the women less than 75 years of age who had taken estrogen for seven or more years, the bone density was, averaging all sites, 11.2 percent greater than in women who had never received estrogen. Among women 75 years of age and older in whom the duration of therapy was comparable, bone density was only 3.2 percent higher than in women who had never taken estrogen.
For long-term preservation of bone mineral density, women should take estrogen for at least seven years after menopause. Even this duration of therapy may have little residual effect on bone density among women 75 years of age and older, who have the highest risk of fracture.
雌激素疗法可预防绝经后早期开始使用该疗法的绝经后女性骨质流失。然而，骨折风险在绝经后很久才会达到最高。我们研究了老年女性的骨量是否受早期雌激素使用的影响，以及女性需要服用雌激素多长时间才能使其对晚年骨密度产生有益影响。
1988年和1989年，我们在弗雷明汉研究队列中的670名白人女性（平均年龄76岁；范围68至96岁）中测量了股骨、脊柱、桡骨干和桡骨远端的骨矿物质密度。这些女性在绝经后一直被前瞻性随访，并被反复询问雌激素疗法的情况。在排除骨折后开始服用雌激素的女性后，我们调查了绝经后雌激素疗法是否影响骨密度；在这些分析中，我们对年龄、体重、身高、吸烟、身体活动和绝经年龄进行了校正。
共有212名女性（31.6%）接受了雌激素疗法（平均估计治疗持续时间为5年）。只有服用雌激素7至9年或10年及以上的女性，其骨矿物质密度显著高于未服用雌激素的女性（治疗7至9年，股骨和脊柱部位P<0.05；≥10年，除脊柱外所有部位P<0.05）。在年龄小于75岁且服用雌激素7年及以上的女性中，所有部位的骨密度平均比从未接受过雌激素治疗的女性高11.2%。在治疗持续时间相当的75岁及以上女性中，骨密度仅比从未服用过雌激素的女性高3.2%。
为长期维持骨矿物质密度，女性应在绝经后至少服用雌激素7年。即使是这个治疗持续时间，对于骨折风险最高的75岁及以上女性，对骨密度的残留影响可能也很小。
