Modeling rare blood in Canada

Abstract

BACKGROUND Many countries maintain rare blood programs to provide access to blood for patients with complex serologies. These include a process to screen donors and a registry to record information about rare donors; blood agencies may also freeze some units. However, frozen blood is much more expensive than liquid blood. STUDY DESIGN AND METHODS. A two‐phase approach to analysis was used to evaluate how rare a blood type must be before a frozen inventory is necessary and what screening rates are required to support a rare blood program. A simulation model was employed to evaluate the impact of inventory on patient access. RESULTS Results suggested that, for 27 of 29 phenotypes managed by Canadian Blood Services, insufficient donors had been identified to ensure a stable inventory. Analytic results showed the screening rate necessary to ensure a stable inventory and the time frame to build a rare donor base. Twenty‐nine simulation scenarios were executed to evaluate patient access to rare blood against inventory levels. Results show that some amount of frozen inventory is necessary for phenotypes rarer than 1 in 3000. However, holding more than two units apiece of O−, O+, A−, and A+ did not improve patient access. CONCLUSION While some level of frozen blood is needed for rare blood, large inventories do not improve access. Modest amounts of frozen inventory, combined with increased door screening, provides the greatest chance of maximizing patient access.

Educational Case: Perioperative patient blood management

“… 11 , 12 , 13 , 14 However, autologous donation often plays an important role in the procurement of blood with rare RBC phenotypes. 15 …”

Probabilistic mathematical modelling to predict the red cell phenotyped donor panel size

“…The Canadian Blood Service (CBS) is responsible for providing blood to all areas of Canada, outside of Quebec, and has approximately 450,000 donors providing around 900,000 units of RBCs annually. It was estimated that 20–30% of these donors have some level of extended phenotyping, beginning with extended Rh (C, c, E and e) and K phenotyping and then on to Duffy (Fy a and Fy b ), Kidd (Jk a and Jk b ), S and s typing on subsequent donations if indicated [ 6 ]. CBS found that with a screening rate of 30%, it would take three to five years to achieve a sufficient registry to service their population [ 6 ].…”

“…It was estimated that 20–30% of these donors have some level of extended phenotyping, beginning with extended Rh (C, c, E and e) and K phenotyping and then on to Duffy (Fy a and Fy b ), Kidd (Jk a and Jk b ), S and s typing on subsequent donations if indicated [ 6 ]. CBS found that with a screening rate of 30%, it would take three to five years to achieve a sufficient registry to service their population [ 6 ]. Following on from this, they estimated an ongoing screening rate of 10–20% for their new donors to maintain a stable inventory.…”

“…Following on from this, they estimated an ongoing screening rate of 10–20% for their new donors to maintain a stable inventory. This analysis was based on a rare donor turnover of less than 10% each year, and the addition of related donors for each new rare donor discovered from the screening [ 6 ].…”

Heat, cold, cryopreservation, and wine

“…In a recent review, Blake and Clarke suggest that although cryopreservation of red cells is needed for rare blood groups large inventories do not improve access. Modest amounts of frozen inventory, combined with increased donor screening, provide the greatest chance of maximizing patient access [4]. Some military preserve platelets in DMSO as they may be better for the treatment of traumatic injury (personal communication D O'D IBTS).…”