Renal toxicity in patients with multiple myeloma receiving zoledronic acid vs. ibandronate: a retrospective medical records review.

AIMS This retrospective study investigated the rates of renal impairment in patients with multiple myeloma treated with zoledronic acid and ibandronate. MATERIALS AND METHODS We retrospectively reviewed medical records in a German oncology clinic, from May 2001 to December 2005. Creatinine measurements were analyzed from baseline (before zoledronic acid or ibandronate treatment) to last evaluation for each patient. A total of 84 patients were included. RESULTS Zoledronic acid increased the risk of renal impairment by approximately 3-fold compared with ibandronate (renal impairment rates: zoledronic acid 37.7% vs. ibandronate 10.5%, relative risk [RR]=3.6, P=0.0029 serum creatinine [SCr]; 62.3% vs. 23.7%, RR=2.6, P=0.0001 glomerular filtration rate [GFR]). Ibandronate-treated patients switched from zoledronic acid had a significantly higher risk of renal impairment than patients receiving ibandronate monotherapy (zoledronic acid over ibandronate 39.1% vs. ibandronate monotherapy 6.7%, RR= 5.9, P=0.028 [SCr]; 65.2% vs 26.7%, RR=2.4, P=0.022 [GFR]). Multivariate analysis found significantly higher hazard ratios for zoledronic acid over ibandronate (SCr: Cox = 4.38, P=0.01; Andersen-Gill=8.22, P < 0.01; GFR: Cox = 4.31, P < 0.01; Andersen-Gill = 3.71, P < 0.01). CONCLUSIONS Overall, this retrospective study suggests that multiple myeloma patients are more likely to experience renal impairment with zoledronic acid than with ibandronate. The risk of renal impairment increased if patients had received prior therapy with zoledronic acid.