Bone mineral density thresholds for pharmacological intervention to prevent fractures

Treatment intervention thresholds for prevention of osteoporotic fractures can be derived from reports from the World Health Organization (diagnostic criteria) and National Osteoporosis Foundation (treatment criteria). It is not known how well these thresholds work to identify women who will fracture and are therefore candidates for treatment interventions. We used data from the National Osteoporosis Risk Assessment (NORA) to examine the effect of different treatment thresholds on fracture incidence and numbers of women with fractures within the year following bone mineral density measurement.

The study comprised 149 524 white postmenopausal women aged 50 to 104 years (mean age, 64.5 years). At baseline, bone mineral density was assessed by peripheral bone densitometry at the heel, finger, or forearm. New fractures during the next 12 months were self-reported.

New fractures were reported by 2259 women, including 393 hip fractures; only 6.4% had baseline T scores of -2.5 or less (World Health Organization definition for osteoporosis). Although fracture rates were highest in these women, they experienced only 18% of the osteoporotic fractures and 26% of the hip fractures. By National Osteoporosis Foundation treatment guidelines, 22.6% of the women had T scores of 2.0 or less, or -1.5 or less with 1 or more clinical risk factors. Fracture rates were lower, but 45% of osteoporotic fractures and 53% of hip fractures occurred in these women.

Using peripheral measurement devices, 82% of postmenopausal women with fractures had T scores better than -2.5. A strategy to reduce overall fracture incidence will likely require lifestyle changes and a targeted effort to identify and develop treatment protocols for women with less severe low bone mass who are nonetheless at increased risk for future fractures.