The purpose of this study is to study the efficacy of denosumab, a new drug, in the treatment of osteoporosis in patients using bisphosphonates.

There are no data on the use of denosumab in steroid induced osteoporosis. Postmenopausal women with chronic use of Glucocorticoid (GCs) are at high-risk of osteoporotic fractures. Despite bisphosphonate treatment, a certain proportion of high-risk patients using chronic GCs either do not achieve a satisfactory gain in bone mineral density (BMD) or develop new fragility fractures. Thus, more potent osteoporosis treatment is necessary for this subgroup of patients. This prompts the current study which aims to examine the efficacy of denosumab in current users of oral bisphosphonates for Glucocorticoid-induced Osteoporosis (GIOP).

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.