The Center Effect: Transplants and Patient Survival

Pancreas transplantation is an effective, long-term treatment for patients with type 1 diabetes mellitus. For patients with diabetes mellitus and end stage renal disease (ESRD), simultaneous pancreas-kidney (SPK) transplantation improves patient and allograft survival compared to deceased donor kidney transplant alone.

Tarek Alhamad

A recent study in Transplantation headed by Assistant Professor of Medicine Tarek Alhamad, MD, in the Division of Nephrology found that centers with a high volume of pancreas transplantation have better patient and allograft outcomes.

For complex surgical procedures such as organ transplantation, it is well-established that the number of procedures performed per year is associated with allograft and patient survival. This so-called center effect applies to a variety of solid organ transplantations (i.e., liver, heart, kidney and lung); centers with a high volume of transplantation have improved patient outcomes. However, the impact of transplant center volume on pancreas allograft survival had not been evaluated.

In a retrospective study of data from the Organ Procurement and Transplantation Network, Dr. Alhamad’s study looked at 11,568 simultaneous pancreas/kidney (SPK) transplants and 4308 solitary pancreas transplants. The average annual transplant center volume was categorized into low (1-6), medium (7-13) and high (14-34) volume of procedures for (SPK), and low (1-3), medium (4-10), and high (11-33) for solitary pancreas transplants. Pancreas Donor Risk Index (PDRI) was also calculated and stratified using 10 donor factors and 1 transplant factor including donor age, gender, race, body mass index (BMI), height, cause of death, preservation time, donation after cardiac death, terminal creatinine and cold ischemia time.

The study showed that patients transplanted at high volume centers had better pancreas survival rates across all categories of PDRI. Patients transplanted at centers performing low volumes of pancreas transplants have inferior short- and long-term allograft survival rates than those transplanted at higher volume centers, despite the fact that the low volume centers had more favorable donor selection. The reasons for this center effect are most likely multifactorial, involving training and experience of personnel, center resources, ancillary care etc.

However, the study did show that allograft survival at some low volume centers is excellent. Identifying the factors that improve patient outcomes irrespective of center volume will be extremely valuable in the future to enhance transplant success in all centers.

Other authors of the study are: Andrew F. Malone, MD; Daniel C. Brennan, MD; Robert J. Stratta, MD; Su-Hsin Chang, PhD; Jason R. Wellen, MD, Timothy A. Horwedel, PharmD; and, Krista L. Lentine, MD, PhD. This study, accepted “without revisions” for publication in Transplantation, can be read in full here.