The amount of time a candidate is on the Wait List. Waiting times can be influenced by many factors, including:
Blood type (some are rarer than others)
Tissue type
Height and weight of transplant candidate
Size of donated organ
Medical urgency
Time on the waiting list
The distance between the donor’s hospital and the potential donor organ
How many donors there are in the local area over a period of time and
The transplant center’s criteria for accepting organ offers
Depending on the kind of organ needed, some factors are more important than others. (OPTN Glossary May 2021)