Retrospective Study of Blood Transfusion Complications in the Capital Region of Denmark from 1999-2017: Characteristics of Potentially Dangerous Blood Donors?

Special Article - Blood Transfusion

Austin Hematol. 2021; 6(2): 1036.

Retrospective Study of Blood Transfusion Complications in the Capital Region of Denmark from 1999-2017: Characteristics of Potentially “Dangerous” Blood Donors?s

Have SB1*, Hother CE1, von Stemann JH1, Dziegiel MH1,2, Hansen MB1,2 and Ostrowski SR1,2

1Department of Clinical Immunology, Copenhagen University Hospital, Denmark

2Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark

*Corresponding author: Have SB, Department of Clinical Immunology, Copenhagen University Hospital, Rigshospitalet, Blegdamsvej 9, 2100 Copenhagen, Denmark

Received: May 03, 2021; Accepted: May 29, 2021; Published: June 05, 2021


Objectives: We hypothesized that the blood donors most frequently involved in complications would induce more and severe immunologic transfusion complications compared to other donors, i.e. potentially “dangerous”. Secondary aims were differences in demographic variables.

Background: Donor-related mechanisms may contribute to allogeneic blood transfusion complications and may represent a dangerous treatment adverse event.

Materials and Methods: By analyzing transfusion data from the Capital Region of Denmark from January 1, 1999 to December 31, 2017; 2,574,646 blood transfusions and 9,779 transfusion complications from 194,432 blood donors were included in our dataset. We divided donors into three groups based on the number of complications and complication frequency (potentially “dangerous” vs. two differently defined control groups i.e. control 1 and control 2), and compared the nature of transfusion complications and demographic variables by statistical analysis.

Results: There were no differences in the proportion of complication types between the potentially “dangerous” donors and control donors, and no difference in the proportion of complications from RBCs, plasma or platelets according to ABO and RhD blood types. However, more potentially “dangerous” donors were female and had ABO blood type B compared to control donors (p<0.001 and p<0.01, respectively). The potentially “dangerous” donors were younger compared to control donors (40.36 years vs. 45.24 years and 42.84 years, p<0.001).

Conclusion: The potentially “dangerous” did not display more/severe immunologic transfusion complications compared to control donors. However, they differed in regards to gender, age and blood type. Further research regarding the differences in complication frequency per donor and demographic variety is warranted.

Keywords: Blood donors; Transfusion reaction; Blood transfusion; Transfusion medicine


The safety of allogeneic blood transfusions has been significantly improved over the past decades, but blood transfusion still remain associated with adverse events i.e. transfusion complications [1]. Many transfusion complications are today considered “immunologic” due to the involvement of donor and/or recipient immune cells, antibodies, inflammatory signaling molecules etc. in the reaction [2- 4]. It is highly debated whether some blood donors are “potentially “dangerous” i.e., prone to induce more immunologic adverse events in the recipient than what would be expected [5-7]. Donor-related mechanisms contributing to complications and pathophysiologic reactions associated with transfusion of allogeneic blood components represent a dangerous treatment adverse event which is potentially avoidable.

The literature on “dangerous” donors is sparse and previous attempts to find clear evidence on donor characteristics that influence transfusion outcome have not been compelling. Non-infectious donor characteristics have been proposed to have an impact on mortality outcome, with quality of evidence rated low to very-low [8]. Donor characteristics such as gender and age have also been suggested to influence recipient outcome, though this remain debated [8-10]. In contrast, it is evident that antibodies in donor blood may induce transfusion complications in recipients [11,12]. Male onlystrategies for platelet and plasma transfusions significantly reduce the likelihood of Transfusion-Related Acute Lung Injury (TRALI) in multiple studies [13-15], which is explained by females having the highest antibody titers and the highest risk of immunization with subsequent antibody production due to pregnancies [16,17]. Only one case-study has identified a specifically “dangerous” donor, which resulted in multiple complications in 36% of the recipients, including a fatal case of TRALI [18]. This study demonstrated the role of leukocyte antibodies in TRALI but despite this, attempts to predict TRALI from antibody detection in donors have so far been unsuccessful [19,20]. Leukodepletion and male-only transfusions are considered essential for the reduction of transfusion complications [21,22], but multiple studies are now focusing on individual donor specific factors as predictors for outcome [23,24].

In Denmark, a well-established system of reporting transfusion complications is operative on a regional and national basis and all blood components used in Denmark are traceable from donor to recipient. Based on previous studies of donor related transfusion outcomes, the aim of the present study was to investigate a hypothesis of the existence of “immunologically dangerous” blood donors. This was done by retrospectively analyzing and categorizing transfusions and transfusion complications in the Capital Region of Denmark in the period of 1999-2017. Specifically, we compared the frequency of different types of transfusion complications, hypothesizing that blood donors with a history of a high frequency of transfusion complications would induce a higher number and more severe immunologic transfusion complications compared to controls.

Materials and Methods

Study design and database

The study was approved by the Danish Data Protection Agency (VD-2018-186, I-Suite no. 6428) and the Danish Health Authorities, Agency for Patient Safety (case no. 3-3013-2555/1).

This is a retrospective study based on prospectively collected data from the blood bank and transfusion database “Blodflödet”, comprising data on all blood donations, blood production, and blood distribution and transfusion complications from March 1st 1996 onward from hospitals in the Capital Region of Denmark. The present study covered data from January 1st 1999 to December 31st 2017. The extracted data comprised information of both blood donors and recipients, anonymized with unique transfusion-IDs, as well as ABO and RhD blood type (recipients and donors), unique donation ID, date of donation, donor and recipient birth data and gender, date and time of the delivery of blood components for transfusion, type of blood component (Red Blood Cells (RBCs), plasma or platelets), ordering hospital and department and various processing data of the components. We focused on the most common blood components: RBCs (irradiated and non-irradiated), plasma (apheresis, whole blood derived, cryodepleted, cryoprecipitate pool) and platelets (pooled non-irradiated, pooled irradiated, apheresis non-irradiated, apheresis irradiated, all platelet components are leukoreduced). All RBCs were leukoreduced by leukofiltration from 2009, so the non-irradiated RBC components contain both leukoreduced and non-leukoreduced components until 2009 and leukoreduced components from 2009. Male-only strategies for plasma transfusions were introduced in 1999. Female plasma were only transfused in shortage of male plasma, and otherwise used for medicinal production.

Registration of transfusion complications

When a transfusion complication is suspected by clinicians, a formula is filled out and delivered to the Blood Bank for registration of the transfusion complication in Blodflödet together with a specific code for the most likely transfusion complication. Imputability (i.e. the probability that the recipient’s symptoms are associated with the complication) is not assessed by clinicians. More than 30 possible transfusion complications are classified based on international consensus from the International Society of Blood Transfusion [25] (Supplementary 1). According to Danish legislation, transfusion complications are also reported to the Danish Registration of Transfusion Risks (Dansk Registering af Transfusionsrisici, DART), the Danish Patient Safety Database (Dansk Patientsikkerheds Database, DPSD) and/or the Danish Patient Safety Authority (Styrelsen for Patientsikkerhed, STPS) for national hemovigilance depending on severity. We classified the transfusion complications into following groups: i) Acute mild immunological complications, ii) Acute severe immunological, iii) Unknown acute immunological, iv) Delayed immunological complications, v) Non-immune mediated complications and vi) Respiratory complications, (Table 1 for classification of complications). The severity of transfusion complications (acute mild vs. acute severe immunological) was based on whether the complication was life threating or potential lifethreatening based on a clinical assessment by the authors. Since this is a retrospective study, TRALI and TACO was not classified according to the newer definitions from 2019 [2,26].