Can the interval between antibody identifications be increased for alloimmunized patients?

Area of Science:

• Transfusion Medicine
• Immunology
• Clinical Pathology

Background:

• New alloantibody formation is unpredictable in alloimmunized patients.
• Current pretransfusion testing intervals are regulated, but antibody identification (ABI) intervals for alloimmunized patients are not standardized.
• Institutions often use a 72-hour interval for pretransfusion specimens to align with AABB standards.

Purpose of the Study:

• To evaluate the safety and feasibility of extending the interval for antibody identification (ABI) testing in alloimmunized patients.
• To determine the incidence of new clinically significant alloantibody formation within a 14-day period.
• To assess the risk versus resource benefits of altering ABI testing frequency.

Main Methods:

• A retrospective review of laboratory information system data over 2 years.
• Screening of 8948 antibody identification (ABI) entries.
• Confirmation of newly developed antibody specificities by four transfusion medicine physicians.

Main Results:

• Thirty patients formed 33 new alloantibodies within 14 days.
• Only 13 antibodies (0.15% of all ABIs, 0.47% of examined alloimmunized patients) were newly formed and clinically significant.
• The incidence of new clinically significant alloantibodies developing within 14 days was low.

Conclusions:

• A small but significant percentage (0.47%) of previously alloimmunized patients develop new clinically significant antibodies within 14 days.
• Extending the interval between antibody identification (ABI) testing may offer resource advantages.
• The risk of potential hemolytic transfusion reactions outweighs the resource benefits of increasing the ABI testing interval.