Vignettes in osteoporosis: a road map to successful therapeutics

Standards for performing DXA in individuals with secondary causes of osteoporosis

This document addresses skeletal health assessment in individuals with secondary causes of osteoporosis. Recommendations are based on consensus of the Canadian Panel of the International Society for Clinical Densitometry and invited international experts. Bone mineral density (BMD) testing in these populations is performed in conjunction with careful evaluation of the disease state contributing to bone loss and increased fragility fracture risk, as well as assessment of other contributing risk factors for fracture. The presence of secondary causes of bone loss may further increase the risk of fracture independently of BMD and may necessitate earlier pharmacologic intervention. Dual-energy X-ray absorptiometry is indicated in the initial workup of secondary causes of osteoporosis. The BMD fracture risk relationship is not known for individuals with chronic renal failure (CRF). The BMD testing in this population may be normal in the presence of skeletal fragility, and quantitative bone histomorphometry is better at evaluating skeletal status than BMD in CRF. Dual-energy X-ray absorptiometry is a valuable tool in assessing skeletal health in individuals with secondary causes of osteoporosis.

Simple Computer Model for Calculating and Reporting 5-Year Osteoporotic Fracture Risk in Postmenopausal Women

PURPOSE

To devise, validate, and test a software model that improves how clinicians calculate individual risk for osteoporotic fracture and expected treatment benefit.

METHODS

We developed a simple model of seven easily ascertained items plus bone mineral density (BMD) that calculates absolute fracture risk and expected absolute risk reduction after treatment. Baseline clinical variables and longitudinal fracture data from two large osteoporosis cohort studies validated the model's accuracy in predicting fracture risk. We then surveyed 298 clinicians to evaluate the likelihood they would prescribe alendronate in three hypothetical cases, first given the clinical data alone and then with model-derived data on fracture risk and expected treatment benefit.

RESULTS

We found a strong linear relationship with the model's predicted fracture risk and observed fracture rates in two large observational cohorts but the model overestimated risk 2-3 fold. The model predicted a 1:200 5-year risk for spinal fracture and a 1:40 risk for nonspinal fracture in an index case of a younger, thin, osteopenic woman. Given this hypothetical history with BMD t-scores, 26% of clinicians were likely to prescribe alendronate; when also given model-calculated 5-year fracture risks with or without treatment, only 13% were likely to prescribe alendronate (p < 0.001). For 2 other osteoporosis patients in whom risk was much higher, further information on fracture risk and expected treatment benefit did not alter prescribing.

CONCLUSIONS

Reporting absolute fracture risk with and without treatment promises to be most useful in women with osteopenia, a common clinical dilemma in younger postmenopausal women.