The enrollment period was from see more July 2003 to June 2006, and the study finished in June 2009. All patients who underwent hip fracture surgery at the participating institutions and were discharged during the enrollment period were tentatively enrolled by uploading data to a web page. The enrollment items were sex, age, height, body weight, body mass index (BMI), presence/absence of osteoporosis, presence/absence of vertebral fracture, site of hip fracture surgery, date of injury, date of hospitalization, treatment of the fracture, address at the time of injury, postoperative period, independence rating before injury, independence rating at discharge, drug

treatment for osteoporosis at discharge, past history at discharge, complications at discharge, BMD, and possibility/impossibility of outpatient follow-up. The attending physician explained the purpose and methods of this study to each patient. We specified Japanese criteria for the diagnosis of osteoporosis according to the diagnostic standard for primary osteoporosis (2000 revised edition) of the Japanese Society for Bone and Mineral Research [19]. The exclusion

criteria were as follows: (1) no diagnosis of primary osteoporosis according to the above criteria, (2) bilateral hip fracture, (3) prior history of hip fracture, (4) patients CA4P ic50 discharged death, and (5) patients who could not be followed-up after discharge. Out of the preliminary enrolled patients, those treated with risedronate at the approved Japanese dose of 2.5 mg/day (Benet® 2.5 mg; Takeda Pharmaceutical Co., Ltd, Osaka, Japan) at the initial visit after 4SC-202 discharge on the judgment of the physician

in charge were included in the administration group. Following the initial outpatient visit after discharge from hospital, patients were enrolled by uploading the required data to the web page. After enrollment of patients in the group receiving BCKDHA risedronate, the patient enrollment center selected all of the matching patients as candidates for the control group. The demographic data and other items used for matching the groups are listed in Appendix 1. Patients in the control group were not being treated with any bisphosphonate preparation and the required data was uploaded as the control group to the web page (Fig. 1). Fig. 1 Disposition of the patients. Of the 2,051 patients who underwent preliminary enrollment, 1,142 patients were ineligible, and 280 patients were excluded from enrollment for several reasons. Among the rest, 184 patients were taking risedronate at the initial outpatient visit after discharge. Four hundred forty-five patients were matched with patients with taking risedronate.