Study design of multi-center, open-label randomized controlled, head-to-head trial comparing minodronic acid and raloxifene: Japanese Osteoporosis Intervention Trial (JOINT)-04.

We planned to conduct multi-center, open-labeled, blinded-endpoints, head-to-head randomized trial of minodronate and raloxifene to compare incidences of vertebral and non-vertebral fractures. The study is the Japanese Osteoporosis Intervention Trial protocol number 4 (JOINT-4). Here, we present the pre-fixed study design. The inclusion criteria are ambulatory older women with osteoporosis, aged > 60 years, and without pre-specified risk factors for secondary osteoporosis and dementia. The subjects who meet selection criteria will be randomly allocated to the raloxifene (60 mg/day) or minodronate (1 mg/day or 50 mg/4 weeks) groups using the central registry. The co-primary endpoints are osteoporotic (vertebral, humeral, femoral, and radial), vertebral, and major osteoporotic (clinical vertebral, humeral, femoral, and radial) fractures. Furthermore, we plan to use the Hochberg procedure to preserve an overall type 1 error rate. In addition, changes in bone mineral density (BMD), hip-structure analysis (HSA) variables, height, bone turnover markers, serum cholesterol and triglyceride concentrations, dental health questionnaire, fall frequency, fall risk index, nursing care level, physical function, quality of life (QOL), and safety profiles were assessed as secondary endpoints. To detect 24% reduction of major osteoporotic fractures with 80% power and a two-sided significance level of 5% with a 2-year observation period, 1734 patients/treatment arm would be required. Subgroup analysis stratified to the following factors age, body mass index, BMD, 25-hydroxyvitamin D concentration, estimated glomerular filtration rate (eGFR), prevalent vertebral fracture number, hypertension status, and diabetes mellitus is pre-specified. The protocol is registered in the trial registry system, and the trial identification number is UMIN000005433.