Denosumab in Current Users of Bisphosphonates for Glucocorticoid-induced Osteoporosis

Inclusion Criteria: 1. Women or adult men (\>18 years of age) with various medical diseases requiring long-term prednisolone treatment. Pre-menopausal women should have no plan for pregnancy within 2 years of study entry and agree to practice contraception during this 2-year period. 2. A daily dose of prednisolone (or equivalent) of more than 2.5mg within 3 months of study entry. 3. Having received oral bisphosphonate treatment for at least 2 years. 4. Suboptimal response to bisphosphonate treatment, defined as either one of the following: (1) failure of lumbar spine, femoral neck or total hip BMD values to increase; (2) values of lumbar spine, femoral neck or total hip BMD remain osteoporotic, ie. T scores \< -2.5 or Z scores \< -2.0; or (3) development of new fragility vertebral or non-vertebral fractures despite at least 2 years' treatment with good compliance. 5. Informed consent from patients. Exclusion Criteria: 1. Patients with previous use of denosumab or teriparatide. 2. Premenopausal women who plan for pregnancy within 2 years of study entry or who do not agree for contraception within this 2-year period. 3. Patients with known bone disorders such as osteomalacia, renal osteodystrophy, and hyperparathyroidism. 4. Patients with unexplained hypocalcemia. 5. Patients with serum creatinine level of \>=200umol/L.