Low Intraindividual Variability of Cyclosporin A Exposure Reduces Chronic Rejection Incidence and Health Care Costs

Abstract

Abstract. The present study applied a receiver operating characteristic (ROC) analysis to assess the role of intraindividual variability of cyclosporin A (CsA) drug exposure in predisposing renal transplant recipients to the occurrence of chronic rejection, as well as to increased health care costs using a resource-based economic analysis. Two hundred and four adult renal transplant recipients were treated with tapering doses of prednisone (Pred) and with a concentration-controlled strategy that selected doses of the olive oil-based formulations of CsA (Sandimmune®) that achieved target concentrations based on serial pharmacokinetic profiles. The ROC analysis revealed an inflection point of plots of the coefficient of variation (%CV) of CsA exposureversusthe risk of chronic rejection at ≥28.4% for the average concentration (Cav),i.e., the dosing interval-corrected area under the concentration-time curves, and ≥36% for the trough concentration (C0). The incidence of chronic rejection over a period of 5 yr was 24% among the less variable (LV)versus40% among the variable (V) cohort. The economic analysis revealed that the total mean facility and physician costs per patient were $48,789versus$60,998, respectively (P< 0.01). The degree of variability displayed by any individual could only be predicted by serial measurements of CsA concentrations, and not by demographic features, laboratory determinations, clinical characteristics, individual or mean values of any observed CsA concentration, or other pharmacokinetic parameters calculated following a single drug exposure. Thus, strategies that reduce intrapatient variability of CsA exposure over time may lead to reductions in chronic allograft loss and in treatment costs.