The importance of early cyclosporine levels in pediatric kidney transplantation.

We studied the impact of early cyclosporine (CSA) levels on the incidence of rejection in pediatric transplant recipients. Between 1 January 1984 and 31 December 1994, a total of 234 pediatric patients underwent kidney transplants and received CSA immunosuppression. We analyzed the impact of CSA levels (at 1 wk, 2 wk, 1 month, 2 months, and 3 months) on the incidence of rejection in the first 3 and the first 6 months post-transplant. We found that CSA levels at all timepoints correlated, i.e. recipients with low levels in the early post-transplant period tended to have low levels throughout the first 12 months. Multivariate analysis for risk factors by biopsy-proven rejection in the first 3 months revealed that the CSA trough level was the critical factor (p < 0.05). Recipients with CSA trough levels < 100 ng/ml had 2.24 times the risk of rejections vs. those with blood levels > 100 ng/ml. Similarly, the CSA trough level at 1 month was the critical risk factor for biopsy-proven rejection within the first 6 months (p < 0.05). The major risk factor for graft loss within the first 12 months was a biopsy-proven rejection episode. We conclude that in pediatric kidney transplant recipients, early CSA trough levels < 100 ng/ml are associated with a significantly increased incidence of rejection in the first 6 months post-transplant.