Late reduction in cyclosporine dosage does not improve renal function in pediatric heart transplant recipients

To determine the relation between cyclosporine (CSA) dosage and late renal function in pediatric heart transplant recipients.

In this retrospective study, pediatric patients were observed for at least 3 years after transplantation, with serial measurement of renal glomerular filtration rate (GFR). Patient variables examined included pre-existing disease (cardiomyopathy or congenital heart disease), age at transplantation, duration of follow-up, and CSA dosage and trough levels at 3 months after transplantation and yearly until the latest follow-up. For each patient, the least squares regression method was used to estimate the average rate of change per year (slope value) for GFR and CSA dosage during follow-up.

Twenty-five patients who met the study criteria underwent transplantation at a median age of 11.7 years (interquartile range [IQR], 6.8-14.5 years) and were observed for a median of 6.0 years (IQR, 4-7). The median GFR at 1 year after transplantation was 73 ml/min/1.73 m(2) (IQR, 50-89) and at latest follow-up was 75 ml/min/1.73 m(2) (IQR, 57-98). The median CSA dosage and trough level at 1 year after transplantation were 6.1 mg/kg/day and 234 ng/ml, and at latest follow-up were 3.45 mg/kg/day and 141 ng/ml, respectively. The median rate of change in GFR was +1.6 ml/year of observation (95% confidence interval, -0.9, 4.7) and was inversely related to measured GFR at 1 year after transplantation. The rate of change of GFR was unrelated to any other patient variables including CSA dosages and levels at the specified time intervals and the rate of change of CSA dosage.

Measured GFR in pediatric cardiac transplant recipients treated with CSA is moderately depressed at 12 months after transplantation and does not change significantly during subsequent years. No evidence suggests that the usual progressive reduction in CSA dosage influences renal function beyond 1 year after transplantation.