Biological and psychological differences in the child and adolescent transplant recipient

  Solid organ transplantation has become accepted therapy for the treatment of end‐stage organ dysfunction in children. As early management of the pediatric transplant recipient has improved, important age‐related differences in long‐term patient outcomes have become apparent. Late morbidity and mortality can, in most cases, be attributed to the consequences of long‐term immunosuppression: graft loss from under‐immunosuppression or an increased incidence of cancer, hypertension, renal failure or diabetes from over‐immunosuppression. Age‐related differences in both biological and psychological factors play an important role in the optimization of therapy in the transplanted child. Important age‐related differences have been demonstrated in all phases of pharmacokinetics: absorption, distribution, metabolism and elimination. Information regarding specific age‐related pharmacokinetic differences is lacking for many immunosuppressive medications. Further study using physiologically based pharmacokinetic (PBPK) models will lead to more specific recommendations for age‐based immunosuppression protocols. Non‐adherence is common among solid organ transplant recipients of all ages and the consequences of non‐adherence include increased rejection, late graft loss and death. The biological and psychological developmental changes that occur during adolescence place the transplanted adolescent at an even higher risk of non‐adherence and poor outcome than other age groups. Further studies to elucidate the importance of both age‐related pharmacokinetic and behavioral factors are needed to formulate therapeutic interventions that would improve adherence and patient outcomes.