In this issue, AABB brings readers interviews with two notable hemovigilance experts — conveners of the international transfusion-associated circulatory overload (TACO) and transfusion-related acute lung injury (TRALI) definition revision projects: Johanna Wiersum-Osselton, MD, PhD; and Alexander Vlaar, MD, PhD, MBA.
Wiersum is the national medical coordinator of the Transfusion and Transplantation Reactions in Patients (TRIP), a national vigilance organization in the Netherlands that gathers adverse occurrence reports in transfusion and transplantation, including tissue and cell vigilance. She has served as national medical coordinator since the organization’s inception in 2002. Wiersum also serves as a donor physician for Sanquin, the Dutch blood supply organization.
Wiersum obtained her medical degree in Leiden, Netherlands, in 1981 and went on to work in the United Kingdom and Guinea. In 2000, she completed specialty training in community medicine. She obtained a PhD in medicine with a thesis titled, “Hemovigilance: is it making a difference to safety in the transfusion chain,” in 2013.
AABB: Can you explain why it was necessary to improve/revise the 2011 ISBT-INH TACO definition?
Wiersum: From early on, people working in hemovigilance had a number of issues with the former TACO definition. Notably, cases were clinically diagnosed as TACO, and accepted as such by hemovigilance (HV) systems, yet they did not meet the criteria of the 2011 definition. Patients with TACO may become hypotensive, instead of their blood pressure going up. The term tachycardia (one of the 2011 criteria) is very non-specific, and sometimes these clinical data are not provided. Also, the U.K. hemovigilance system, SHOT (Serious Hazards of Transfusion), reported that features consistent with TACO could become apparent longer than 6 hours after transfusion.
What are the difference between the
new TACO definition and the former 2011 ISBT-IHN TACO definition?
There are three main differences:
Cases may occur longer than 6 hours after transfusion (up to 12 hours). It is easier for a case to qualify even if no chest X-ray has been performed. Overall, there are more combinations of signs and symptoms which can add up to meet the criteria. The revised definition has been tested in a validation exercise (The Lancet Haematology, May 2019) and it gives better agreement with the cases which were being reported to HV systems.
What effect do you think the new definition will have in the hemovigilance systems analyzing transfusion adverse reactions?
The revision group hopes that hemovigilance systems will start to formally use the revised definition. When we carried out the validation, some systems were using the ISBT criteria but if a case was clinically a TACO, they accepted it as TACO even if it did not meet enough criteria. Other systems had their own definition. The criteria in the revised definition are also useful for asking hospitals to go back and see if the information is actually there, though not initially reported. So, we should see a better quality of information and more harmonization of reporting TACO cases within and between systems.
The new definition still doesn’t make it easy to determine between TRALI and TACO in difficult cases, but it includes guidance notes on specific features of the radiography or clinical exam to support this.
What effect do you think the new definition will have in clinical settings?
It is important to be aware that the definition was developed as a surveillance definition, which means that all information can be considered, including whether the patient improved following diuresis and whether the NT-proBNP level was increased in the hours following the reaction. The definition is not intended and has not been tested as a clinical tool for doctors and nurses to recognize TACO in a patient who becomes short of breath during or after a transfusion. Nevertheless, the new definition will assist in promoting awareness of this important transfusion complication and can become an international reference point for collaboration and research to increase insights into pathophysiology and to develop evidence-based tools and guidelines for prevention and treatment of TACO.
Vlaar is a consultant in Intensive Care Medicine and principal investigator at the Department of Intensive Care Medicine of the Amsterdam UMC in Amsterdam, Netherlands, whose research focuses on transfusion-related morbidity and mortality. His research lines consist, among others, of pre-clinical and clinical investigation in the field of antibody and non-antibody mediated TRALI.
AABB: Can you explain why it was necessary to improve/revise the 2011 ISBT-INH TRALI definition?
Vlaar: The need to revise the TRALI definition has been realized by the transfusion medicine professional and hemovigilance expert community through research and development in the field over the past decade. Several commentary letters were published in
Transfusion in 2016 addressing the need for an update of the 2004 Canadian Consensus Conference (CCC) definition. In addition, the 2012 Berlin definition that redefined acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) hadn’t been integrated to the transfusion medicine field yet. Therefore, a panel of experts convened to review the TRALI definition and apply Delphi panel method to achieve consensus. There was no funding sponsorship available for the project.
What are the differences between the
new TRALI definition and the former 2011 ISBT-IHN TRALI definition?
First, the term possible TRALI (pTRALI) has been dropped because of its ambiguity and also to incorporate recent evidence that inflammation is almost always a pre-requisite for TRALI. Second, we introduced the terms TRALI Type I and TRALI Type II. TRALI Type I occurs in patients with no risk factors for acute respiratory distress syndrome (ARDS), and TRALI Type II occurs in patients who have risk factors for ARDS (with no diagnosis of ARDS yet) or those who have existing mild ARDS whose respiratory status worsens due to transfusion. Third, we harmonized the new TRALI definition with the 2012 Berlin criteria by modifying the 2004 CCC ARDS risk factor lists and also expanded chest CT scan and lung ultrasound as possible diagnostic evaluation for bilateral pulmonary edema and left arterial hypertension (LAH). Finally, we provided some suggested clarification to define ARDS and cases where TRALI/TACO cannot be distinguished, to avoid post-transfusion respiratory adverse reaction cases being lumped into the “other” category.
What effect do you think will the new definition have in the hemovigilance systems analyzing transfusion adverse reactions?
We hope the new definition will be adopted by the hemovigilance systems. We previously sent the updated TRALI definition to hemovigilance societies for feedback and we received some constructive comments which were incorporated into the published updated definition (Transfusion, July 2019). We will also present the new TRALI definition at conferences and will attempt to publish letters to the editor in other peer-reviewed journals in order to increase awareness of the new definitions. The group is also planning to develop a universal reporting form for respiratory transfusion reactions that we hope to publish in a peer-reviewed journal. We believe, with the availability of a universal reporting form and acceptance of standard definition, researchers will be able to make comparisons of reaction rates between various hemovigilance systems.
What effect do you think will the new definition have in clinical settings?
In our publication, we mention that TRALI is a clinical diagnosis and we emphasize that TRALI determination should not be limited to presence of leukocyte antibodies. Rather, TRALI should be diagnosed based on clinical presentations. We hope that with adoption of the new definition all post-transfusion respiratory adverse reactions will be reported for further investigation. We believe that classifying transfusion reactions accurately based on our proposed standard definitions will allow for uniform comparisons and, thereby, increase our knowledge concerning pulmonary transfusion complications.