Incidence of hypocalcemia in patients receiving denosumab for prevention of skeletal-related events in bone metastasis.

Background Denosumab therapy is commonly used for the prevention of skeletal-related events in patients with bone metastasis. However, a common side effect of denosumab is hypocalcemia. Objective The aim of the study is to determine the incidence of hypocalcemia in patients receiving denosumab for prevention of skeletal-related events in bone metastasis and evaluate risk factors for developing hypocalcemia. Methods This was a retrospective medication use evaluation reviewing the incidence of hypocalcemia in patients receiving outpatient denosumab for prevention of skeletal-related events at Yale-New Haven Hospital. Additionally, various risk factors were reviewed to determine their risk of developing hypocalcemia. Results As per Common Terminology Criteria for Adverse Events v4.03, of the 106 patients included in the study population, 37 (35%) patients had an incidence of hypocalcemia within 30 days of denosumab administration. Fourteen patients (13.2%) had an incidence of grade 1, 13 patients (12.3%) had an incidence of grade 2 hypocalcemia, and 7 patients (6.6%) had an incidence of grade 3 hypocalcemia. Grade 4 hypocalcemia occurred in three (2.8%) patients. Calcium supplementation did not decrease the risk of developing hypocalcemia. Patients who had one or more episodes of acute kidney insufficiency were at a higher risk of developing hypocalcemia (odds ratio = 7.5 (95% confidence interval = 1.8-36.3), p = 0.001). Conclusion This study found that the overall incidence of hypocalcemia and severe hypocalcemia was higher than reported in clinical trials. Additionally, calcium supplementation did not have an effect on incidence of hypocalcemia, while patients who experienced acute kidney insufficiency while on denosumab had a higher likelihood of developing hypocalcemia.