Blood transfusion-associated anaphylaxis in perioperative- and non-perioperative patients in Western Norway 2002-2021.

Background: Anaphylaxis after blood transfusion is a feared complication accounting for severe morbidity. A retrospective study was performed at Haukeland University Hospital, Bergen, Norway, to investigate the rate and features of transfusion-associated anaphylaxis (TAA) occurring between 2002-2021.

Materials and methods: Identified cases of TAA were studied by an immunologist and an allergist to extract information about general characteristics, amplifying factors, co-morbidity, treatment, and treatment responses. TAA was reported as perioperative or non-perioperative.

Results: We identified 29 cases of TAA: 13 perioperative and 16 non-perioperative. Allergic transfusion reaction had an incidence rate of 34/100,000 transfusions and TAA a rate of 7/100,000 transfusions. The incidence of allergic reactions and TAA increased 2.6- and 6.4-fold during the study period. The first perioperative TAA was discovered 12 years into the study period but was equally frequent as non-perioperative transfusion-associated anaphylaxis in the last five years of the study period. 52% of the TAA cases had relevant co-morbidity and 100% of them had amplifying factors. Although only 38% of the non-perioperative patients received epinephrine as treatment, 94% of them had a good treatment response to their total treatment regimen. Poorer treatment response was observed with higher age, more cardiovascular- and respiratory disease, higher use of amplifying and sedating medications and a higher severity score.

Discussion: Our findings indicate that TAA, especially in the perioperative setting, is underdiagnosed. The increased incidence of TAA in our study is temporally related to the introduction of a national hemovigilance program, introduction of standardized laboratory testing for anaphylaxis and increased multidisciplinary focus on the condition. In conclusion, increased awareness of TAA, and especially in the perioperative setting, is needed. A multidisciplinary approach is necessary to improve identification and reporting of TAA.