Long‐Term Comparison of Tacrolimus‐ and Cyclosporine‐Induced Nephrotoxicity in Pediatric Heart‐Transplant Recipients

Nephrotoxicity is an adverse effect of cyclosporine and tacrolimus. Studies comparing their long‐term nephrotoxicities are lacking. This study evaluates the nephrotoxicity of these agents over a 7‐year period following heart transplantation. Pediatric heart‐transplant recipients receiving cyclosporine or tacrolimus as primary immunosuppression were evaluated at two centers from 1982 to 1998. Data collected included serum creatinine, height and weight prior to transplantation, at 1 and 6 months and 1 years post transplantation, and at yearly intervals thereafter. Creatinine clearance was calculated and compared between the two groups. Glomerular filtration rate was measured using Tc‐99 m diethylenetriaminepentacetic acid. In total, 123 patients were evaluated. Demographic data of the two groups were comparable. Creatinine clearance demonstrated a steady decline. This decline did not differ statistically between the two groups: tacrolimus 98.9 and 90.7 mL/min/1.73 m2 at 1 month and 5 years, respectively; cyclosporine 110.7 and 81.7 mL/min/1.73 m2 at 1 month and 5 years, respectively. Four patients developed end‐stage renal failure. Calculated creatinine clearance consistently overestimated glomerular filtration rate, the latter being greater than 2 standard deviations below the mean normal in 38% of patients. We conclude that the nephrotoxicities of tacrolimus and cyclosporine are comparable over the medium‐ to long‐term in pediatric heart‐transplant recipients.