e., maintained a medical possession ratio to initiated therapy of at least 80%). At cohort entry, the ibandronate cohort was the youngest and had the smallest percentage

with a recent fracture history among the three cohorts (Table 1). Since a subject was allowed to enter a cohort after 6 selleck compound months without any bisphosphonate use, some subjects had some previous use of bisphosphonates. Prior use of bisphosphonates in the 4 years prior to cohort entry ranged from 7% of alendronate cohort to 40% of ibandronate cohort. Table 1 Baseline characteristics of study population   Alendronate Risedronate Ibandronate 70 mg 35 mg 150 mg Number of women in cohort 116,996 78,860 14,288 Year of cohort entry, % cohort       2000–2004 78% 73% 0% 2005–2006 22% 27% 100% Age at cohort entry, mean 75 76 75 Age 75 and BMS202 concentration over, Rabusertib ic50 % cohort 51% 53% 47% Clinical fracture in 6 months before cohort entrya 9% 9% 7% Clinical fracture in 4 years before cohort entryb 19% 18% 17% Glucocorticoid use at cohort entry 5% 6% 6%

Rheumatoid arthritis diagnosis at cohort entry 2% 3% 3% Hormone replacement therapy at cohort entry 14% 12% 9% Prior bisphosphonate use, % cohortc       6 months before cohort entry 0% 0% 0% 1 year 4% 5% 18% 2 years 6% 10% 30% 3 years 7% 12% 36% 4 years 7% 13% 40% aFracture diagnosis at the hip, clavicle, wrist, humerus, leg, pelvis, or vertebral sites bFracture diagnosis at any time in the 4 years before cohort entry among those with 4 years of available Lck administrative billing data before cohort entry (17,128 subjects in alendronate cohort had

4 years of such data, 15,054 in risedronate cohort, 7,884 in ibandronate cohort) cUse of any bisphosphonate (e.g., daily formulations or other bisphosphonate) before cohort entry regardless of duration of administrative billing data before entry. Note: among those with 4 years of available data before entry, the percent of cohort in the preceding 4 years with bisphosphonate use was 9%, 19%, and 47% for alendronate, risedronate, and ibandronate cohorts, respectively Baseline incidence of hip fractures During the 3 months after starting therapy in all three cohorts, the incidence of hip fractures was higher among those of greater age, prior fracture history, and glucocorticoid use, and lower among those with use of hormone replacement therapy (Table 2). During these 3 months, patients receiving risedronate had an incidence of hip fractures that was 141% of the incidence among those receiving ibandronate and 117% of the incidence among those receiving alendronate. After statistically adjusting (by direct standardization to risedronate cohort) for age, fracture history, and prior bisphosphonate use, patients receiving risedronate had an incidence of hip fractures that was 132% of the incidence among those receiving ibandronate and 114% of the incidence among those receiving alendronate.