Bisphosphonates reduce the rate of osteoporotic fractures in clinical trials and community practice. ''Atypical'' nontraumatic fractures of the diaphyseal (subtrochanteric or shaft) part of the femur have been observed in patients taking bisphosphonates. We calculated the incidence of these fractures within a defined population and examined the incidence rates according to duration of bisphosphonate use. We identified all femur fractures from January 1, 2007 until December 31, 2011 in 1,835,116 patients older than 45 years who were enrolled in the Healthy Bones Program at Kaiser Southern California, an integrated health care provider. Potential atypical fractures were identified by diagnostic or procedure codes and adjudicated by examination of radiographs. Bisphosphonate exposure was derived from internal pharmacy records. The results showed that 142 patients had atypical fractures; of these, 128 had bisphosphonate exposure. There was no significant correlation between duration of use (5.5 AE 3.4 years) and age (69.3 AE 8.6 years) or bone density (T-score À2.1 AE 1.0). There were 188,814 patients who had used bisphosphonates. The age-adjusted incidence rates for an atypical fracture were 1.78/100,000/year (95% confidence interval [CI], 1.5-2.0) with exposure from 0.1 to 1.9 years, and increased to 113.1/100,000/year (95% CI, 69.3-156.8) with exposure from 8 to 9.9 years. We conclude that the incidence of atypical fractures of the femur increases with longer duration of bisphosphonate use. The rate is much lower than the expected rate of devastating hip fractures in elderly osteoporotic patients. Patients at risk for osteoporotic fractures should not be discouraged from initiating bisphosphonates, because clinical trials have documented that these medicines can substantially reduce the incidence of typical hip fractures. The increased risk of atypical fractures should be taken into consideration when continuing bisphosphonates beyond 5 years. ß

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The authors thank the entire Healthy Bones Team in Southern California and all of the other Kaiser Permanente regions who have worked so hard to make our osteoporosis disease management program a huge success. Our Healthy Bones Program has touched the lives of hundred of thousands of patients by improving their bone health and decreasing their risk of sustaining fractures.

NPs play an important leadership role in managing osteoporosis within a large health maintenance organization. The screening and interventions used can be applied by any NP in any practice setting on an individual basis to reduce hip fracture rates in the United States.

Clinical practice guidelines for the treatment and prevention of AFF will benefit clinicians who are frequently faced with having to make clinical decisions in patients requiring antiresorptive medications.