Every One Counts: A Retrospective Cohort Study Examining the Safety of Extending Pre-Transfusion Compatibility Testing from 72 Hours to 7 Days in Hematology Patients Receiving Red Blood Cell Transfusions

Aims: To investigate the safety of extending the pretransfusion compatibility testing (PTCT) interval from 72 hours to 7 days in hematology patients receiving packed red blood cells (PRBC). Methods: We undertook a retrospective cohort study over two years when the local protocol for PTCT in recently transfused hematology patients was changed from 72 hours to 7 days. All transfusions from 12 months prior and post this date were exported from eBlood and analyzed. The primary outcome was the incidence of transfusion reactions. Subgroup analysis was conducted for the chronically transfused patient group and patients with PTCT > 72 hours. Results: A total of 2079 packs were analyzed from 227 patients. Only 37 transfusions that fulfilled the extended crossmatch. There were five (0.69%) transfusion reactions within the post-protocol change cohort and no transfusion reactions in the pre-protocol change cohort. All transfusion reactions occurred in the greater 72-hour subgroup of the post-protocol change cohort. At the time of reaction, there were no alloantibodies identified. No patients demonstrated new alloantibodies post-reaction. Conclusion: This study found no evidence for an increased risk of transfusion reactions associated with increasing the PTCT interval from 72 hours to 7 days in a subset of chronically transfused hematology patients. Extending the PTCT interval could decrease costs, decrease patient infection risk, improve comfort, and conserve public health resources. Further evaluation in a larger cohort is necessary.