Bone Abstracts

Background: Intravenous zoledronic acid is a common treatment for osteoporosis as it powerfully inhibits osteoclastic bone resorption and has a long duration of effect. It is recommended as a treatment to prevent a range of fractures in those who have osteoporosis diagnosed by DEXA or have had previous vertebral or hip fractures, but are unable to take oral bisphosphonates. Zoledronic acid has been associated with nephrotoxicity. The impact of repeated doses of zoledronic acid on renal function in adults with osteoporosis has not been well researched in a clinical setting. This study aimed to assess whether repeated doses of zoledronic acid were associated with a change in eGFR. Secondary aims included assessing the proportion of patients who had a clinically meaningful decline in eGFR and whether this was influenced by baseline renal function.

Methods: A retrospective observational audit was performed using routine clinical data from 697 adult patients who received one, two or three annual doses of IV zoledronic acid as a treatment for osteoporosis, with an eGFR measured prior to each infusion. The NHS Greater Glasgow Clyde electronic medical records system (Clinical Portal) was used to search for eGFR and creatinine values prior to each infusion and creatinine clearances (CrCl) were calculated using an online calculator and then compared to baseline.

Results: Over the three infusions the median eGFR stayed constant and the mean CrCl reduced by 7.9ml/min. 1.04% of patients had a significant reduction in eGFR before infusion two and 1.64% before infusion three. 3.5% had a significant reduction in CrCl before infusion two and 8.8% before infusion three. Among those with chronic kidney disease at baseline 2.1% had a significant decline in renal function at any point.

Conclusion: Repeated doses of zoledronic acid to treat osteoporosis in adults were not found to be associated with a significant change in eGFR. This study found no association between lower baseline renal function and the renal impact of zoledronic acid.