Highlights from the World Transplant Congress 2014

20 November 2014  // 

Organ Recovery Systems was delighted to exhibit at the 2014 World Transplant Conference in San Francisco, USA, on July 26–31. The Congress was the second joint meeting of the American Society of Transplant Surgeons, The Transplantation Society and the American Society of Transplantation, and followed the previous successful meeting in 2013, which was attended by over 6500 specialists in the field of transplantation.

A group from the University of Toronto, Ontario, Canada presented data from a cross sectional study that investigated discard in extended criteria donor (ECD)/donation after circulatory death (DCD) kidneys from 2000 to 2011.1 Donor characteristics and Kidney Donor Risk Index (KDRI) scores were recorded for both discarded and transplanted ECD/DCD kidneys and multivariable logistic regression models were used to determine the likelihood of discard based on donor characteristics. A total of 894 kidneys were included in the study of which 34.2% were discarded. Median KDRI in transplanted versus discarded kidneys was significantly different (IQR0.69 vs. 0.89, respectively; p = 0.001); however, there was considerable overlap in the distribution of KDRI scores between both groups. The likelihood of discard was significantly higher in diabetic or hepatitis B or C positive donors.  Hypothermic machine perfusion was associated with a lower likelihood of discard (p = 0.01). Age, race, death by cardiovascular accident, hypertension and weight were not associated with an increased likelihood of discard. The authors concluded that there is a high rate of discard among ECD/DCD kidneys but given their favorable donor characteristics and KDRI scores, some of these may have been suitable for transplantation.

A recently published study by Gill J et al, of US registry data for 94,709 renal transplants between 2000 and 2011 found that the use of pulsatile perfusion significantly reduces the risk of DGF irrespective of donor type and CIT.2 When stratified by donor type and CIT, the risk of DGF with hypothermic machine perfusion (HMP) was lower for all CIT in standard criteria donor (SCD) transplants and when CIT was ≥6 hours in expanded criteria donor (ECD) transplants. CIT between 6–24 hours was independently associated with a greater risk of DGF irrespective of storage method in donation after circulatory death (DCD) transplants. However, this effect was significantly modified, by using hypothermic machine perfusion (HMP).

In two further presentations by the authors at WTC, the results of which follow on from the published study, the risk of DGF was examined in HMP kidneys.A new analysis of data from kidney pairs where one patient showed DGF and the other did not was conducted in 30,302 donor recipients between 1998 and 2011.4 After adjustment for relevant transplant and recipient risk factors, DGF was associated with a 2.2-fold increase in death censored graft loss and a 1.8-fold increased risk of all cause graft loss. However, DGF with concurrent acute rejection was associated with a 3-fold increased risk of all cause graft loss and with a 1.7-fold without acute rejection. Delayed graft function was associated with several factors including a history of diabetes or peripheral vascular disease, prior transplantation, cold ischemic time (CIT) >12 hours and the use of static cold storage (SCS). The researchers concluded that the occurrence of delayed graft function confers an independent risk of graft loss in kidney transplant recipients.

In a second presentation, the authors sought to refine the criteria for the use of hypothermic machine perfusion by examining the impact of HMP on DGF for each decile of Kidney Donor Profile Index (KDPI).5 The study examined all deceased donor kidney transplants between 1995 and 2010 (>100,000) and stratified them into deciles of KDPI based on their KDRI. After adjustment for CIT, hypothermic machine perfusion was associated with a reduced risk of DGF in all deciles of KDPI except the lowest risk decile. Hypothermic machine perfusion was also consistently associated with a reduced risk of DGF when KDPI was >0.30 when stratified according to cold ischemic categories, even when CIT was <12 hours. 

These new analyses demonstrate that hypothermic machine perfusion reduces the risk of DGF irrespective of donor type, cold ischemia time and KDRI.

Dr. James Guarrera, Columbia University Medical Center, New York, USA, presented the most recent data from his group, which has recently been accepted for publication in the American Journal of Transplantation.5 His study examined the use of hypothermic machine perfusion versus static cold storage (SCS) in patients receiving extended criteria donor (ECD) livers or livers that had initially been rejected by the originating United Network for Organ Sharing (UNOS) region, known as ‘orphan’ livers.

The study enrolled two groups of patients receiving isolated primary liver transplantation. Using an early prototype of the LifePort® Liver Transporter, in the intervention arm, 31 patients received hypothermic machine perfusion livers and in the control arm, 30 patients receiving livers after SCS were matched for donor age, recipient age, cold ischemic time (CIT), donor risk index and model end-stage liver disease (MELD) score. During the 12-month post transplantation follow-up there were significantly fewer biliary complications in the hypothermic machine perfusion group versus SCS (4 vs. 13, respectively; p = 0.016), and early allograft dysfunction rates were also lower in the hypothermic machine perfusion group (19% vs. 30%). In addition, mean hospital stay was significantly shorter in the hypothermic machine perfusion group (13.6 vs. 21.1 days; p=0.001).

Dr. Guarrera concluded that hypothermic machine perfusion assists in the safe use of ECD livers, even those rejected by multiple centers. He suggested that this technique will be effective in reducing the incidence of preservation injury in the most susceptible livers, and that its incorporation into clinical practice will help close the gap between organ supply and demand. 

 

  1. Abstract #654. Determinants of Discard of Kidneys From Expanded Criteria Donors Undergoing Donation After Circulatory Death. S. Singh & S. Kim, University of Toronto, Toronto, ON, Canada.
  2. Gill J et al. Pulsatile Perfusion Reduces the Risk of Delayed Graft Function in Deceased Donor Kidney Transplants, Irrespective of Donor Type and Cold Ischemic Time Transplantation. Transplantation 2014;97(6):668–674.
  3. Abstract #1426. The Impact of DGF On Kidney Allograft Survival: A Paired Kidney Analysis. J. Gill, J. Dong, C. Rose, J. Gill. University of British Columbia, Vancouver, Canada.
  4. Abstract # 1467. The Utility of Pulsatile Perfusion Across the Spectrum of Deceased Donors Using the KDPI. J. Gill, J. Dong, M. Eng, J. Gill. University of British Columbia, Vancouver, Canada.
  5. Guarrera JV et al. Hypothermic machine preservation facilitates successful transplantation of “orphan” extended criteria donor livers. Accepted for publication Am J Transpl 2014.