Multi-Organ Transplant Program

Organ Allocation

In Canada, approximately 4,000 men, women, and children are waiting for organ transplants to save or improve their lives. Many thousands more wait for a tissue donation to improve the quality of their lives. How do patients get on the transplant waiting list? How is it decided which patient gets the donated organ?

Patients are approved for transplant following intense physical and psychosocial assessments by the specialized health-care team at the transplant hospital. The transplant surgeons make the final decision, based on their knowledge of the patient and the input from other members of the health-care team. The potential recipient is then assigned a "status code". This number describes the medical condition of the patient while he/she waits. The lowest number (1) indicates a patient whose health is relatively stable and who is waiting at home or out of the hospital. The highest number (4) indicates a patient who is on life support in an Intensive Care Unit and will die within days without a transplant. This number changes as the patient's condition changes so that any available organ is offered to the sickest patient first. A sharing agreement exists across Canada so that the sickest person on the list, regardless of location, is transplanted.

Other factors also enter into the decision-making process. The date and time that a patient's name is added to the waiting list becomes important if there are several patients with the same medical status code. In this situation, the patient listed first will be offered the organ first. Blood type is also important. Except with a status 4 patient, surgeons prefer that the blood group of the donor and the recipient is identical or compatible. The size difference between donor and recipient is another factor. Obviously, a heart from an 80 kilogram donor is too large for a patient who only weighs 5 kilograms. To some extent, the liver can be reduced in size so that an adult liver may be transplanted into a smaller recipient such as a child.

For kidney patients, the selection process is different because we use tissue-typing tests. The Transplantation and Immunogenetics Laboratory at LHSC performs tests that "type" donors and recipients and measure antibody levels (crossmatching) that are important in avoiding kidney rejection. The donor's blood and spleen are tested against blood samples from potential recipients. The kidney is transplanted into the recipient who has the closest tissue match and the greatest likelihood of success.

In Ontario, the Trillium Gift of Life Network is responsible for establishing and managing waiting lists for organs and tissue, as well as ensuring a system of fair allocation:

Algorithm for kidney allocation (deceased donor)

Algorithm for liver allocation (deceased donor) -- currently being revised

Algorithm for heart allocation

Algorithm for lung allocation