Agent	Interventions	Study population(s)	Total body bone mineral density saved peryear (%)	Number ofpatient-years of treatment required to prevent one fracture	Number of patient-years of treatment required toprevent one vertebral fracture	Annual cost per patient33 *	Cost per fracture prevented†
Calcium and vitamin D26,27	500 mg of elemental calcium per day and 700 to 800 IU of cholecalciferol per day	Healthy ambulatory female residents in nursing homes or assisted living facilities and men and women over 65 years old	1.0	45 patient-years	—	$ 22	$ 1,000
Alendronate (Fosamax)20,28	10 mg per day, plus 500 mg of elemental calcium per day	Postmenopausalwomen with osteoporosis	0.8	63 patient-years	99	696	58,300
Etidronate (Didronel)29,30	400 mg per day for 14 days every 3 months, plus 500 mg of elemental calcium per day	Postmenopausal women with osteoporosis	0.5 to 1.3‡	Not significant	96	162	16,700
Estrogen31	0.625 mg of conjugated estrogens per day plus 10 mg of medroxy-progesterone acetate on days 10 through 25, plus calcium in a variable dosage (depending on dietary intake) with vitamin D in a dosage of 400 IU per day	Healthy postmenopausal women	0.5	Not measured	—	255	25,800
Raloxifene (Evista)32	60 mg per day	Postmenopausal women	0.7	Not measured	—	723	69,400