What's New in Childhood Organ Transplantation

Transplantation remains the most effective treatment for children who have end-organ failure. In this review, we summarize the current issues facing children and their treating physicians following transplantation of whole organs. Although recipients of allogeneic bone marrow can follow a similar clinical course as organ recipients, bone marrow transplantation as a therapy has additional unique posttransplant features that are not covered in this article.

Regardless of transplant type, common themes emerge.

Children differ from adults in their immune responses, in the way they metabolize many drugs, and in their susceptibility to many of the adverse effects of transplantation and immunosuppression. Drug regimens based on induction immunotherapy with interleukin-2 receptor antagonists or anti-lymphocyte antibody coupled with tacrolimus-based long-term immunosuppression have increased in prevalence. Long-term exposure to immunosuppressive medications, however, has led to increased drug-related morbidities. Hyperlipidemia, hypertension, cardiovascular disease, malignancy, and diabetes mellitus have emerged as significant concerns. Nonadherence to immunosuppressive regimens, particularly among adolescents, contributes to increased graft failure.

Despite these obstacles, posttransplant pediatric patient and graft survival have been improving steadily. Nationwide data indicate that patient and graft survival rates are equivalent to or better than adult survival rates. Successful delivery of care for the long-term well-being of these patients demands communication between the patient and a complex of many physicians, from the earliest encounters with general pediatricians to more specialized care with

Renal Transplantation

In the early 1960s when clinical renal transplantation was just beginning to be used for patients who had end-stage renal disease (ESRD), a few children received allografts in major transplant centers. A decade later, renal transplants were adopted as the optimal treatment for children who had ESRD. Kidneys are transplanted more frequently than any other organ and comprise 45% of all pediatric transplants. Of all renal transplants performed nationwide, 7% are performed in patients ages 17 years or younger.

At every age level, the 3-year survival of patients following deceased donor (DD) or living donor (LD) transplant exceeds survival on dialysis. Data analyzed by age group indicate that following transplantation, life expectancy increased "by 30 years for children aged 0 to 14 years, with a calculated remaining lifetime expectancy of 50 years," and in patients ages 15 to 19 years old, "25 years with a calculated remaining lifetime expectancy of 40 years."

The demographics of pediatric kidney transplantation have changed over the past 2 decades. Boys continue to account for approximately 59% of recipients, but the percentage of black (17%) and Hispanic (16%) recipients has increased to 28% and 33%, respectively. Most pediatric kidney transplants occur in adolescents (38.4%) or children ages 6 to 12 years (33.7%). The primary diseases leading to ESRD in children are significantly different from those in adults and differ between black and white patients. For black patients, the five most prominent causes of renal failure are focal segmented glomerulosclerosis (FSGS) (23%), obstructive uropathy (15%), aplasia/hypoplasia/dysplasia (14%), chronic glomerulonephritis (4%), and systemic lupus erythematosus nephritis (4%); for white patients, the most common causes are obstructive uropathy (17%), aplasia/dysplasia/hypoplasia (17%), FSGS (9%), reflux nephropathy (6%), and medullary cystic disease (4%). Many diseases that cause ESRD in children can cause continued problems posttransplant, notably obstructive uropathies, dysplasia syndromes, and recurrent FSGS. Pretransplant native nephrectomy, which occurs in approximately 23% of recipients, often is a consideration in patients displaying polyuria, electrolyte wasting, proteinuria, recurrent pyelonephritis, and hypertension.