Estimating bisphosphonate use and fracture reduction among US women aged 45 years and older, 2001-2008.

Oral bisphosphonates are first-line therapy for the prevention and treatment of osteoporosis in postmenopausal women. Although bisphosphonate treatment has been shown to reduce fractures in randomized, controlled trials, the number of women treated and fractures prevented over the years have not been determined. This study estimated the numbers of women treated and fractures reduced with oral bisphosphonates in the United States from 2001 through 2008. Two medical claims databases for 2001-2008 were combined to determine numbers of women aged 45 years and older filling prescriptions for bisphosphonates by time-dependent medication possession ratios (MPRs): <50%, 50% to 79%, and ≥ 80%. Fracture incidence was compared for each cohort by MPR category relative to the referent cohort with <50% MPR. Fracture rates were extrapolated to the US female population treated with oral bisphosphonates by MPR category over this 8-year period. From 2001 through 2008, 460,584 women in the databases initiated treatment with oral bisphosphonates, with an average follow-up time of 2.4 years. Overall fracture rates declined with improved MPR from 1.52% for the lowest MPR category to 1.18% for the highest MPR category for ages 45 to 64 years and from 5.12% to 3.75% for those aged 65 years or older. Extrapolating to the US population of female bisphosphonate users, we estimate over 27.9 million person-years of bisphosphonate treatment with MPR 50% or greater and 144,670 fractures prevented. Treatment with oral bisphosphonates has prevented a substantial number of fractures. Even more fractures would have been prevented if recognition, treatment, and compliance were improved.