The Effect of Bisphosphonates on Kidney Function in Osteoporotic Geriatric Patients with Impaired Renal Function

Background Bisphosphonates are the mainstay treatment for osteoporosis, with initiation guided by creatinine clearance (CrCl) from the Cockcroft-Gault equation. However, many clinicians use estimated glomerular filtration rate (eGFR) from the CKD-EPI equation, primarily for chronic kidney disease (CKD) staging. Objectives To compare renal function assessments derived from the two equations and evaluate changes over a 12-month treatment. Methods A retrospective cohort study compared renal outcomes in osteoporotic geriatric patients with an eGFR ranging from 35 to 60 mL/min/1.73m² who received bisphosphonate between January 2015 and December 2022. Patients were categorized based on CrCl: <35 mL/min and ≥ 35 mL/min using the Cockcroft-Gault equation Results A total of 222 patients (190 [85.6%] female; mean age 80 ± 6.54 years) were analyzed, with 109 (49.1%) in the CrCl < 35 group and 113 (50.9%) in the CrCl ≥ 35 group. No significant differences in overall renal function changes were observed. The CrCl < 35 group had higher relative risk (RR) of renal function change events with an adjusted RR of 6.77 (95% CI: 1.53 to 29.88; p = 0.012) at 6 months and an adjusted RR of 3.75 (95% CI: 1.04 to 13.50; p = 0.043) at 12 months. Conclusions Calculating CrCl using the Cockcroft-Gault equation is crucial in older patients before bisphosphonate therapy. Although no significant differences in overall renal function changes were observed, the CrCl < 35 group demonstrated trends of renal function decline and higher relative risk of renal function change events at months 6 and 12.