Risk of renal impairment after treatment with ibandronate versus zoledronic acid: a retrospective medical records review.

ABSTRACT

PURPOSE: This retrospective study compared renal impairment rates in breast cancer, multiple myeloma, prostate cancer and non-small cell lung cancer patients treated with ibandronate or zoledronic acid. STUDY DESIGN: Medical records in two German oncology clinics from May 2001 to March 2006 were retrospectively reviewed. Creatinine measurements were analyzed from baseline (before bisphosphonate treatment) to last available measurement for each patient. The Cox proportional hazards model and the Andersen-Gill extension of the Cox model for multiple events analysis were used for multivariate analysis, which controlled for age, clinic site, primary cancer type, baseline SCr or GFR value, prior bisphosphonate use, concomitant use of drugs associated with acute renal failure, and renal-related comorbidities. RESULTS: Of 333 patients, 109 received ibandronate and 256 received zoledronic acid (32 patients had both drugs). Compared with ibandronate, the zoledronic acid group had a significantly better baseline renal function and fewer patients had a history of renal disease. Zoledronic acid treatment increased the relative risk (RR) and the incidence rate (IR) of renal impairment by approximately 1.5-fold in all assessed patients (all tumors) compared with ibandronate. Multivariate analysis found significantly higher hazards ratios for zoledronic acid over ibandronate (two to sixfold), after adjusting for differences in characteristics between the two treatment groups. CONCLUSIONS: In this retrospective review, patients were significantly more likely to experience renal impairment with zoledronic acid than with ibandronate.