Osteoporosis
CMAJ 1997;156:1530
Re: "Effects of ovarian hormone therapy on skeletal and extraskeletal tissues in women" (CMAJ 1996;155[suppl]:929-34 [full text]), Dr. Robert G. Josse
In response to: K.G. Marshall
Dr. Marshall's comments provide emphasis to our conclusions regarding the timing of ovarian hormone therapy. Although we agree that achievement of maximum benefits of hormone therapy on bones probably depends on continued or at least long-term (more than 10 years') use, we feel that the evidence supporting this position is not as strong as it should be. We chose not to cite the article by Felson, Zhang and Hannan, which concluded that estrogen should be taken for more than 7 to 10 years after menopause to achieve a measurable benefit after age 75. The authors' main conclusions were based on studying only 24 women 75 years of age or older who took estrogen longer than 7 years. Only 3 of the 24 were still taking estrogen when the data were analysed. We cited the article by Cauley and associates, which found that the major benefits in fracture prevention were seen only in women currently taking estrogen (both short- and long-term users), although the most benefit was seen in the subjects who started taking estrogen within 5 years of menopause. Neither of these studies addressed the issue of fracture prevention before the age of 65.
The problem with these studies is that they were not interventional, and the use of hormone therapy by the subjects was influenced by a wide variety of variables that were not under the control of the investigators. As we pointed out, there is a paucity of prospective randomized controlled trials of hormone therapy. We applaud the long-term prospective randomized controlled trial being undertaken in the Women's Health Ini-
tiative under the auspices of the US National Institutes of Health. This study will address the safety of longer-term hormone therapy, and the results should be available in about 7 years.
The initiation of hormone therapy long after menopause is still likely to have significant benefits, and physicians should not be pessimistic about this issue in discussing therapy with their patients.[1] The double-blind, randomized, placebo-controlled clinical trial that showed benefits of estrogen therapy in fracture prevention as well as bone density was carried out in postmenopausal women whose average age was 65 years.[2]
It is important to note that our article was a consensus statement agreed to and written by the members of the Scientific Advisory Board of the Osteoporosis Society of Canada. Consensus statements are always a compromise, and our plan is to continue to revise our position as more evidence becomes available. The publication of our article is simply one stop along the road.
We do not see any major discrepancies between our conclusions and those of the articles cited by Marshall. As we stated, ovarian hormone therapy "should be continued for a minimum of 10 years beyond menopause for maximum bone protection." However, one should not infer from this statement that these are the only conditions under which estrogen has a preventive or therapeutic effect.
David A. Hanley, MD
Professor of Medicine
University of Calgary
Chair
Consensus Conferences
Osteoporosis Society of Canada
Calgary, Alta.
Robert G. Josse, MD
Professor of Medicine
University of Toronto
Chair
Scientific Advisory Board
Osteoporosis Society of Canada
Toronto, Ont.
References
- Schneider DL, Barrett-Connor EL, Morton DJ. Timing of postmenopausal estrogen for optimal bone mineral density: the Rancho Bernardo Study. JAMA 1997;277:507-602.
- Lufkin EG, Wahner HW, O'Fallon WM, et al. Treatment of postmenopausal osteoporosis with transdermal estrogen. Ann Intern Med 1992;117:1-9.
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