Estrogens forever? Never too late to start?
2-2 TIMING OF POSTMENOPAUSAL ESTROGEN FOR OPTIMAL BONE MINERAL DENSITY
There is little agreement on the optimal time to start and stop estrogen replacement therapy (ERT). Concerns about breast cancer and other possible risk factors associated with estrogen use and the awareness that bone loss continues or even accelerates in old age have raised questions about when to initiate therapy and whether therapy should be discontinued. This study examined past and current use of ERT related to bone mineral density (BMD).
Conclusion: ERT initiated in the menopausal period and continued into late life was associated with the highest BMD. ERT begun after age 60 offered near equal bone-conserving benefit.

STUDY

1. Entered over 70 white middle-upper class women age 60-98.
2. Questionnaire included health habits, medical history, dietary supplements and medications.
3. Measured BMD by absorptiometry at radius, hip, and lumbar spine.

RESULTS

1. Sixty nine percent of women had used oral estrogen after menopause—30% were current users.
2. Identified 5 groups of estrogen users: 1) never users; 2) past users who started at menopause; 3) past users who started after age 60; 4) current users who started at menopause; and 5) current users who started after age 60 (average age at initiation—69 years).
3. In past users, the more recent the estrogen use, the higher the BMD, independent of age.
4. Current users who started at menopause had the highest BMD levels at all sites—significantly higher than never-users or past users.
5. Among current users there was no significant difference in BMD at any site between those who started ERT at menopause (with 20 years use) and those who started after age 60 (with 9 years of use).
6. Current continuous users users had 7% to 20% higher mean BMD than never users. Current late users had similarly higher mean BMD.
7. Past users had 2% to 11% higher BMD than never users.

DISCUSSION

1. Current continuous users had the highest BMD levels. This forms the rationale for current clinical recommendations to begin estrogen at menopause and continue into late life.
2. Maximum increases in BMD are thought to occur during the first few years of ERT, then show a trend toward stabilization or slow decline. The benefit in older women is probably due to the same mechanism observed in younger women with a reduction of bone resorption proportional to the available estrogen-dependent bone fraction.
3. ERT taken only at the time of menopause preserves bone during use, but it may not preserve bone density late in life. There is a rapid loss of BMD 1 year following cessation of ERT.
4. These data provide some of the strongest evidence to date that estrogen therapy should be continues into late life for the maintenance of high bone density. Past estrogen use provides little or no long term benefit for the preservation of bone density because accelerated bone loss occurs after discontinuation of estrogen, rather like the accelerated bone loss at menopause.
5. If late continuous use is equivalent to early-onset continuous use, estrogen could be initiated at older ages to obtain benefit.

CONCLUSION
Estrogen initiated in the menopausal period and continued into late life was associated with the highest bone density. Estrogen begun after age 60 and continued appeared to offer nearly equal bone-conserving benefit.

JAMA February 19, 1997; 277: 543-47 Original investigation from Univ. Of California, San Diego, LA, Jolla. CA

Comment:
Although BMD is a surrogate marker for fractures, I believe it has been demonstrated that fractures are more common in women with lower BMD. Older women should also take supplements to ensure adequate calcium and vitamin D. RTJ

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