The time between when a patient is registered on a waiting list and when that patient receives a transplant. Annual Report tables show the median and other percentiles of time to transplant. The median time to transplant is the time by which 50% of a group of registrants have received a transplant. Among the factors affecting time to transplant are the shortage of organs; biologic issues such as blood type, body size of donors and recipients, PRA, immunological factors, and medical urgency status (for liver and heart); donation rates within an area; donation request and consent procedures at OPOs; and patient registration and organ acceptance practices at transplant centers. Table 1.6 presents an alternative measure, "waiting time before transplant," in which inactive time on the waiting list is not counted and patients are censored at any removal from the waiting list.