Alendronate prevents bone loss in patients following discontiuation of Hormone Replacement Therapy
Hormone replacement therapy has been shown to be effective in reducing postmenopausal bone loss and increasing bone mass. However, recent studies confirming the possible detrimental effects of this therapy have brought the use of HRT into question leading many women to stop treatment. Many postmenopausal women who discontinue hormone replacement therapy (HRT) experience a rapid decline in bone density. Ascott-Evans, et al (Arch Intern Med 163:789, 2003) evaluate the safety and efficacy of alendronate in preventing bone loss following HRT discontinuation.
Methods: A total of 119 patients who stopped HRT < 3 months prior to the start of this study were enrolled. Patients completed a 12 month placebo controlled trial (95 received alendronate; 49 received placebo) comparing bone mass density (BMD) measurements of the lumbar spine, hip, and total body at 0, 6 and 12 months. Serum bone-specific alkaline phosphatase (BSAP) and urinary N-telopeptide were measured also as biochemical markers for bone formation and resorption. Patients could not have had a prior osteoporosis related fracture.
Results: In both treatment groups, the average age of patients enrolled was 57, and approximately 90% were Caucasian. The average number of years of post-menopausal state was 11 years for both groups. Baseline lumbar spine BMD T score was approximately 2.2 for each group. Indicated in the table below, at the end of 12 months of treatment, patients treated with alendronate had significantly higher lumbar spine BMDs than placebo-treated patients. Similar trends were seen in hip and total body BMD.
| Alendronate* (n=95) | Placebo* (n=49) | |
| Lumbar spine BMD | 2.3% (1.7% to 3.0%), p<.001 | -3.2% (-4.6% to – 1.7%) |
| Hip BMD | 2.5% (1.6% to 3.5%), p<.05 | 0.2% (-1.4% to 1.8%) |
| Total Body BMD | 1.0% (0.4% to 1.6%), p<.001 | -0.7% (-1.6 to 0.1%) |
| NTx level | -46.7% (-55.6% to -36.2%) | 35.7% (6.7 to 72.4%) |
| BSAP level | -19.6 (-26.7% to -11.8%) | 17.9% (1.8% to 36.6%) |
| *values represent mean percent change from baseline at 12 months (95% confidence interval) | ||
Conclusion: Following discontinuation of HRT in postmenopausal women, a rapid decline in BMD occurs. Alendronate treatment is efficacious at increasing or maintaining bone mass density, as well as decreasing the rate of bone loss, in this population.
Editorial Comments: These results confirm the rapid onset of bone loss after discontinuation of estrogen. Alendronate, if substituted for estrogen, can prevent this bone loss. This study was too small, however, to correlate BMD findings with fracture rate. Fracture rate is the “gold standard” outcome for assessing the effect of a treatment on osteoporosis.
