Lung and Heart Allocation in the United States

Lung and heart allocation in the United States has evolved over the past 20–30 years to better serve transplant candidates and improve organ utilization. The current lung allocation policy, based on the Lung Allocation Score, attempts to take into account risk of death on the waiting list and chance of survival posttransplant. This policy is flexible and can be adjusted to improve the predictive ability of the score. Similarly, in response to the changing clinical phenotype of heart transplant candidates, heart allocation policies have evolved to a multitiered algorithm that attempts to prioritize organs to the most infirm, a designation that fluctuates with trends in therapy. The Organ Procurement and Transplantation Network and its committees have been responsive, as demonstrated by recent modifications to pediatric heart allocation and mechanical circulatory support policies and by ongoing efforts to ensure that heart allocation policies are equitable and current. Here we examine the development of US lung and heart allocation policy, evaluate the application of the current policy on clinical practice and explore future directions for lung and heart allocation.     

Kidney,Pancreas and Liver Allocation and Distribution in the United States

Kidney transplant and liver transplant are the treatments of choice for patients with end‐stage renal disease and end‐stage liver disease, respectively. Pancreas transplant is most commonly performed along with kidney transplant in diabetic end‐stage renal disease patients. Despite a steady increase in the numbers of kidney and liver transplants performed each year in the United States, a significant shortage of kidneys and livers available for transplant remains. Organ allocation is the process the Organ Procurement and Transplantation Network (OPTN) uses to determine which candidates are offered which deceased donor organs. OPTN is charged with ensuring the effectiveness, efficiency and equity of organ sharing in the national system of organ allocation. The policy has changed incrementally over time in efforts to optimize allocation to meet these often competing goals. This review describes the history, current status and future direction of policies regarding the allocation of abdominal organs for transplant, namely the kidney, liver and pancreas, in the United States.     

Pediatric Transplantation in the United States, 1996–2005

Solid organ transplantation is accepted as a standard lifesaving therapy for end-stage organ failure in children. This article reviews trends in pediatric transplantation from 1996 to 2005 using OPTN data analyzed by the Scientific Registry of Transplant Recipients. Over this period, children have contributed significantly to the donor pool, and although the number of pediatric donors has fallen from 1062 to 900, this still accounts for 12% of all deceased donors. In 2005, 2% of 89 884 candidates listed for transplantation were less than 18 years old; in 2005, 1955 children, or 7% of 28 105 recipients, received a transplant. Improvement in waiting list mortality is documented for most organs, but pretransplant mortality, especially among the youngest children, remains a concern. Posttransplant survival for both patients and allografts similarly has shown improvement throughout the period; in most cases, survival is as good as or better than that seen in adults. Examination of immunosuppressive practices shows an increasing tendency across organs toward tacrolimus-based regimens. In addition, use of induction immunotherapy in the form of anti-lymphocyte antibody preparations, especially the interleukin-2 receptor antagonists, has increased steadily. Despite documented advances in care and outcomes for children undergoing transplantation, several considerations remain that require attention as we attempt to optimize transplant management.     

Unintended Consequences of the New National Kidney Allocation Policy in the United States

The new national Kidney Allocation System of the Organ Procurement and Transplantation Network (OPTN), effective as of December 4, 2014, was designed to improve the chances of transplanting the most highly sensitized patients on the waitlist, those with calculated panel reactive antibody values of 98%, 99% and 100%. Recently, it was suggested that these highly sensitized patients will experience inequitable access, given the reported high prevalence of antibodies to HLA‐DP, and the fact that only about 1/3 of deceased donors are typed for HLA‐DP antigens. Here we report that 320/2948 flow cytometric crossmatches performed for the Northwestern transplant program over the past 28 months were positive solely due to HLA‐DP donor‐specific antibodies (11%; 16.5% of patients with HLA antibodies—sensitized patients). We further show that 58/207 (12%) HLA‐DR serologically matched donor‐recipient pairs had a positive B cell flow crossmatch due to donor‐specific HLA class II antibodies, and 2/34 (6%) serologic zero‐HLA‐A‐B‐DR mismatch had a positive flow crossmatch due to HLA‐DSA. We therefore provide information regarding the necessity and importance of complete donor HLA typing including both chains of the HLA‐DP antigen (encoded by HLA‐DPA1 and HLA‐DPB1) at the time of organ offer.     

Pediatric Transplantation in the United States, 1995–2004

This article reviews trends in pediatric solid organ transplantation over the last decade, as reflected in OPTN/SRTR data. In 2004, children younger than 18 years made up nearly 3% of the 86 378 candidates for organ transplantation and nearly 7% of the 27 031 organ transplant recipients. Children accounted for nearly 14% of the 7152 deceased organ donors. The transplant community recognizes important differences between pediatric and adult organ transplant recipients, including different etiologies of organ failure, surgical procedures that are more complex or technically challenging, effects of development on the pharmacokinetic properties of common immunosuppressants, unique immunological aspects of transplant in the developing immune system and increased susceptibility to posttransplant complications, particularly infectious diseases. For these reasons, and because of the impact of end-stage organ failure on growth and development, the transplant community has generally provided pediatric candidates with special consideration in the allocation of deceased donor organs. Outcomes following kidney, liver and heart transplantation in children often rank among the best. This article emphasizes that the prospects for solid organ transplantation in children, especially those aged 1–10 years are excellent. It also identifies themes warranting further consideration, including organ availability, adolescent survival and challenges facing pediatric transplant clinical research.     

Repeat Organ Transplantation in the United States, 1996–2005

The prospect of graft loss is a problem faced by all transplant recipients, and retransplantation is often an option when loss occurs. To assess current trends in retransplantation, we analyzed data for retransplant candidates and recipients over the last 10 years, as well as current outcomes. During 2005, retransplant candidates represented 13.5%, 7.9%, 4.1% and 5.5% of all newly registered kidney, liver, heart and lung candidates, respectively. At the end of 2005, candidates for retransplantation accounted for 15.3% of kidney transplant candidates, and lower proportions of liver (5.1%), heart (5.3%) and lung (3.3%) candidates. Retransplants represented 12.4% of kidney, 9.0% of liver, 4.7% of heart and 5.3% of lung transplants performed in 2005. The absolute number of retransplants has grown most notably in kidney transplantation, increasing 40% over the last 10 years; the relative growth of retransplantation was most marked in heart and lung transplantation, increasing 66% and 217%, respectively. The growth of liver retransplantation was only 11%. Unadjusted graft survival remains significantly lower after retransplantation in the most recent cohorts analyzed. Even with careful case mix adjustments, the risk of graft failure following retransplantation is significantly higher than that observed for primary transplants.     

Liver and Intestine Transplantation in the United States, 1996–2005

The number of liver transplants performed yearly has slowly and steadily increased over the last 10 years, reaching 6441 procedures in 2005. The number of living donor liver transplants performed rose steadily from 1996 to 2001, when it peaked at 519; since 2003 there have been approximately 320 such procedures performed each year. The continual increase in the size of the waiting list for a liver transplant, which peaked in 2001 at 14 897 patients, was interrupted in 2002 by the implementation of the allocation system based on the model for end-stage liver disease and pediatric end-stage liver disease (MELD/PELD). Activity in all areas of intestinal transplantation continues to increase. One-year patient and graft survival following intestine-alone transplantation now seem to be superior to outcomes following liver-intestine transplantation. Other topics covered here include the recent 'Share 15' component of the MELD allocation system; liver transplantation following donation after cardiac death; simultaneous liver-kidney transplantation and waiting list and post-transplant outcomes for both liver and intestine transplantation, broken out by a variety of clinical and demographic factors.     

Heart and Lung Transplantation in the United States, 1997–2006

This article highlights trends in heart and lung transplantation between 1997 and 2006, drawing on data from the OPTN and SRTR. The total number of candidates actively awaiting heart transplantation declined by 45% over the last decade, dropping from 2414 patients in 1997 to 1327 patients in 2006. The overall death rates among patients awaiting heart transplantation declined over the same period. The distribution of recipients among the different status groups at the time of heart transplantation changed little between the inception of the new classification system in 1999 and 2005. Deaths in the first year after heart transplantation have steadily decreased. At the end of 2006, 2885 candidates were awaiting a lung transplant, up 10% from the 1997 count. The median time-to-transplant for listed patients decreased by 87% over the decade, dropping from 1053 days in 1997 to 132 days in 2006. Selection for listing and transplantation has shifted toward more urgent patients since the May 2005 implementation of a new lung allocation system based on survival benefit and urgency rather than waiting time. Only 31 heart-lung transplants were performed in 2006, down from a high of 62 in 1997.     

Heart and Lung Transplantation in the United States, 1996–2005

This article examines the Organ Procurement and Transplantation Network/Scientific Registry of Transplant Recipients data on heart and lung transplantation in the United States from 1996 to 2005. The number of heart transplants performed and the size of the heart waiting list continued to drop, reaching 2126 and 1334, respectively, in 2005. Over the decade, post-transplant graft and patient survival improved, as did the chances for survival while on the heart waiting list. The number of deceased donor lung transplants increased by 78% since 1996, reaching 1407 in 2005 (up 22% from 2004). There were 3170 registrants awaiting lung transplantation at the end of 2005, down 18% from 2004. Death rates for both candidates and recipients have been dropping, as has the time spent waiting for a lung transplant. Other lung topics covered are living donation, recent surgical advances and changes in immunosuppression regimens. Heart-lung transplantation has declined to a small (33 procedures in 2005) but important need in the United States.     

Regional Variability in Liver Waiting List Removals Causes False Ascertainment of Waiting List Deaths

Inconsistent identification of reasons for removal from the liver transplant waiting list by Organ Procurement and Transplantation Network (OPTN) regions may contribute to regional variability in wait‐list death rates. We analyzed OPTN and Social Security Administration (SSA) reported deaths of 103 364 liver transplant candidates listed May 8, 2003–April 17, 2011, and determined regional variability in risk of death attributable to differences in use of OPTN removal codes. Only 26% of candidates removed as “too sick” died within 90 days of delisting; 6335 deaths after delisting were not reported to OPTN. The ratio of number of candidates removed as “too sick” to number who died on the waiting list varied by region from 0.23 to 0.94, indicating substantial variability in use of removal codes. Including SSA‐reported deaths within 90 days of delisting reduced regional variability in risk of death by 48% compared with deaths on the list alone, and by 35% compared with deaths plus the “too sick” designation. Codes for delisting liver transplant candidates are inconsistently applied among OPTN regions, spuriously elevating estimated regional variability in risk of wait‐list death. This variability is ameliorated by including SSA‐ reported deaths within 90 days of delisting.     

Organ allocation in pediatric transplantation in France

In France, ministerial decrees in 1995 and 1996 gave children under 16 who are awaiting transplantation national priority for kidneys and livers from donors under 16, and regional priority for kidneys and livers from donors under 30. We analyzed the effects of these changes on waiting time, death on the waiting list, and balance between demand and supply. The percentage of children who received a transplant during the year of registration increased from 40% in 1993 to 67% in 1998 for kidney transplantation, but only from 50% to 67% for liver transplantation. The number of new children registered on the renal transplant waiting list (84 in 1998) and the number transplanted (85 in 1998) are balanced. But, because of the number of children still on the waiting list at the end of each year, there remains an imbalance of about 70 for kidney transplantation. For liver transplantation, there remains an imbalance of about 35. Death on the renal transplant waiting list has been below 2% since 1993. Death on the liver transplant waiting list decreased from 10–20% in 1993–1995 to 3% in 1998. The number of children who died on the thoracic organ waiting list in 1998 was the same as the number transplanted. In conclusion, the new rules governing organ allocation to children in France have shortened waiting time for renal transplantation, but not for liver transplantation. Many children still die on the waiting list for thoracic organ transplantation. Received: 4 July 2001 / Revised: 4 October 2001 / Accepted: 4 October 2001