Seeking clarification of osteoporosis guidelines

The recent recommendation statement concerning the prevention of osteoporosis and osteoporotic fractures in postmenopausal women1 was developed after a detailed process of identifying the appropriate analytic framework, systematically reviewing the literature, discussing the evidence at multiple Task Force meetings and subjecting the statement to 2 levels of peer review (internal peer review within the Task Force and external peer review organized by the Task Force).

On the basis of our analytic framework and the evidence available, we concluded that there is no direct evidence that screening reduces fractures. In other words, there were no acceptable randomized controlled trials that directly evaluated routine screening linked to treatment compared with usual care. However, there is evidence that screening is effective in identifying postmenopausal women with osteoporosis. There is also evidence that treating osteoporosis can reduce the risk of fractures in postmenopausal women. Because the evidence that supports fracture reduction through screening is therefore indirect, our overall recommendation was grade B, rather than grade A. Currently, there is much controversy as to what the treatment threshold should be. Most experts agree that postmenopausal women with osteoporosis (T score at or below –2.5) should be treated with pharmacologic therapies, because there is good to fair evidence from randomized controlled trials that such treatment will reduce osteoporotic fractures in this population. Some of these trials have included women with T scores between –2.0 and –2.5.

There is a strong correlation between low bone mineral density (BMD) and fracture risk in postmenopausal women,2^,3 and the risk increases with age for a given level of BMD.4^,5 This predictive ability of BMD for fractures is greater than that of blood pressure for stroke and cholesterol level for cardiovascular disease.2 However, in younger postmenopausal women with low BMD, the absolute risk is low.4Therefore, on the basis of the absolute fracture risk, we recommend BMD screening by DEXA for all postmenopausal women starting at age 65 (see Fig. 1 in our original article1). If the result of the initial DEXA is normal, we recommend repeating this test in 2 years. On the same basis, we also recommend considering pharmacologic treatment for those over age 65 with T scores between –2.0 to –2.5. Those younger than 65 years of age with T scores above –2.0 have a lower absolute risk of fracture and therefore the corresponding number needed to treat to prevent one fracture is higher.

In our statement,1 we were explicit that these recommendations do not apply to those in nursing homes, because we limited our systematic review to the community-dwelling population. We did review compounds that were not available in Canada at the time of our submission for publication but for which published evidence was available (e.g., teriparatide and oral pamidronate), as they may become available here sometime in the future. Current evidence suggests that pharmacologic therapies can further reduce fractures in osteoporotic postmenopausal women who are receiving adequate amounts of vitamin D and calcium. Although we recommend regular exercise because it can maintain BMD and reduce falls, no good evidence exists for fracture reduction with regular exercise in this population.

These evidence-based clinical guidelines are meant to guide physicians in discussions with their postmenopausal patients, as each individual woman may have unique risks and preferences. The guidelines need to be interpreted and applied sensibly. In general, clinical practice guidelines are designed to hasten the incorporation of research findings into routine care, but they are usually not the reference for medicolegal action. Most common law rulings in North America and the United Kingdom are based on minimum acceptable standards of clinical care, which are often derived from responsible customary practice, rather than from clinical practice guidelines.6^,7

The Canadian Task Force for Preventive Health Care is funded through Health Canada and strives to provide up-to-date, unbiased guidelines for primary care physicians in Canada. No drug company was involved financially or otherwise in this recommendation statement.

Angela M. Cheung Department of Medicine University Health Network University of Toronto Toronto, Ont. John W. Feightner Chair, Canadian Task Force for Preventive Health Care Professor, Department of Family Medicine University of Western Ontario London, Ont.