In patients already taking glucocorticoids, a bisphosphonate should be started if the bone mineral density is below a certain threshold. The rationale for using bone mineral thresholds instead of giving bisphosphonates to all is that these drugs have potentially significant side effects and so should not be prescribed if not needed. The appropriate threshold at which intervention should be considered in glucocorticoid-treated patients is a matter of controversy. Based on evidence that fractures occur at a higher bone mineral density in glucocorticoid-treated patients than in postmenopausal women, the UK guidelines 18 recommend starting a bisphosphonate if the T score is less than −1.5 at the spine or hip, but the ACR 17 guidelines propose a T-score cutoff of −1.0. Whichever cutoff is chosen, its significance in terms of absolute fracture risk will differ according to the age of the patient. Therefore, use of T scores as an intervention threshold is not advisable.
The ACR and the UK guidelines both recommend measuring the bone mineral density by dual-energy x-ray absorptiometry at baseline (even though preventive therapy is not based on this value) and repeating it 6 months later and then yearly.
In premenopausal women, bisphosphonates should be used with caution, as they cross the placenta and are teratogenic in animals. Nevertheless, the ACR guidelines 17 state they can be given after appropriate counseling and instruction about contraception.
The UK guidelines 18 note that in the large clinical trials of alendronate and risedronate, the incidence of vertebral fractures was low in premenopausal women, indicating a very low fracture risk. Therefore, the UK guidelines state that bone-active drugs should be reserved for premenopausal women who have very low bone mineral density or who suffer fragility fractures or who have other strong risk factors for fracture.
In children and adolescents, the data are insufficient to produce evidence-based guidelines for the prevention and treatment of glucocorticoid-induced osteoporosis. General measures include using the lowest effective dose of glucocorticoids for the shortest period of time, and considering alternate therapies, calcium and vitamin D supplementation, weight-bearing exercise, and proper nutrition.
Bisphosphonates are recommended when bone mineral density is falling despite these general measures and when “high-dose” glucocorticoids are likely to be used for a “prolonged” time, or in patients who have already had a fracture. 21
Weekly doses may improve compliance
Risedronate is approved by the US Food and Drug Administration (FDA) for the prevention of glucocorticoid-induced osteoporosis, and both risedronate and alendronate are approved for its treatment.
The ACR guidelines recommend the FDA-approved (ie, daily) doses of alendronate and risedronate for glucocorticoid-induced osteoporosis. Most patients, however, are pre-scribed weekly doses of these two agents, as compliance is much greater with this schedule of administration.
Estrogen is being used more selectively
The 2001 ACR guidelines said that, although there were no randomized controlled trials of hormone replacement (or testosterone) therapy to prevent glucocorticoid-induced bone loss, patients receiving long-term glucocorticoid therapy who are hypogonadal should be offered hormone replacement therapy. 17
In 2002, the principal results of the Women’s Health Initiative 22 showed that hormone replacement therapy with estrogen and progesterone was associated with a higher risk of breast cancer. Since then, the consensus has been that hormone replacement therapy should be restricted to women with menopausal symptoms or to older women who cannot tolerate other therapies or who express a strong preference for hormone replacement therapy despite being informed about potential adverse events. 23