Implications of expanding disease definitions: the case of osteoporosis.

The National Osteoporosis Foundation and American College of Obstetrics-Gynecology have expanded osteoporosis therapy recommendations by changing the treatment threshold. We determined the impact of this recommendation using nationally representative U.S. data. The new threshold changes the number of women for whom treatment is recommended from 6.4 million to 10.8 million among women age sixty-five and older (at a net cost of at least $28 billion) and from 1.6 million to 4.0 million among women ages 50-64 (at a net cost of at least $18 billion). Whether or not offering treatment to these additional women will reduce the number of hip fractures is unknown.