Denosumab-associated hypocalcaemia: incidence, severity and patient characteristics in a tertiary hospital setting

Abstract

Purpose Denosumab-associated hypocalcaemia (DAH) has been reported in patients with osteoporosis or metastatic bone disease and is associated with stages 4 and 5 chronic kidney disease (CKD, estimated glomerular filtration rate <30 mL/min/1.73m2). Other risk factors for hypocalcaemia have not been fully elucidated.

We aimed to investigate the incidence of hypocalcaemia amongst patients receiving denosumab and to identify clinical features associated with this adverse event.

Methods Retrospective cohort study between June 2013 and June 2014 of patients administered denosumab (60/120 mg) at a tertiary hospital in Melbourne, Australia, to identify the incidence of an albumin-adjusted serum calcium concentration <2.10 mmol/L or ionized calcium <1.13 mmol/L within 6 months of treatment. Univariable and multivariable logistic regression analyses were performed to identify clinical features associated with DAH.

Results One hundred and fifty-five patients were administered denosumab (100 osteoporosis, 55 bone metastases). Twenty-two patients (14% [95%CI 9.1–20.7]) developed hypocalcaemia: 55% were men, and 55% had osteoporosis. Eighty-six per cent had a 25-hydroxyvitamin D concentration >50 nmol/L, and 91% were on calcium/colecalciferol supplementation. Stages 4 and 5 CKD (adjusted odd ratio [aOR] 4.71, 95%CI 1.61–13.79, p = 0.005) and male sex (aOR 4.30, 95%CI 1.69–10.96, p = 0.002) were associated with DAH. No patients were documented as having hypocalcaemic symptoms. One patient received intravenous calcium gluconate treatment.

Conclusions The incidence of denosumab-associated hypocalcaemia was 14% (95%CI 9.1–20.7) within 6 months of treatment despite widespread use of appropriate calcium/colecalciferol supplementation. Stages 4 and 5 CKD and male sex were associated with subsequent hypocalcaemia.