Risk Factors for Alloimmunisation after red blood Cell Transfusions (R-FACT): a case cohort study

INTRODUCTION: Individuals exposed to red blood cell alloantigens through transfusion, pregnancy or transplantation may produce antibodies against the alloantigens. Alloantibodies can pose serious clinical problems such as delayed haemolytic reactions and logistic problems, for example, to obtain timely and properly matched transfusion blood for patients in which new alloantibodies are detected. OBJECTIVE: The authors hypothesise that the particular clinical conditions (eg, used medication, concomitant infection, cellular immunity) during which transfusions are given may contribute to the risk of immunisation. The aim of this research was to examine the association between clinical, environmental and genetic characteristics of the recipient of erythrocyte transfusions and the risk against erythrocyte alloimmunisation during that transfusion episode. METHODS AND ANALYSIS STUDY DESIGN: Incident case–cohort study. SETTING: Secondary care, nationwide study (within the Netherlands) including seven hospitals, from January 2005 to December 2011. STUDY POPULATION: Consecutive red cell transfused patients at the study centres. INCLUSION: The study cohort comprises of consecutive red blood cell transfused patients at the study centre. EXCLUSION: Patients with transfusions before the study period and/or pre-existing alloantibodies.Cases defined as first time alloantibody formers; Controls defined as transfused individuals matched (on number of transfusions) to cases and have not formed an alloantibody. STATISTICAL ANALYSIS: Logistic regression models will be used to assess the association between the risk to develop antibodies and potential risk factors, adjusted for other risk factors. ETHICS AND DISSEMINATION: Approval at each local ethics regulatory committee will be obtained. Data will be coded for privacy reasons. Patients will be sent a letter and an information brochure explaining the purpose of the study. A consent form in presence of the study coordinator will be signed before the blood taking commences. Investigators will submit progress summary of the study to study sponsor regularly. Investigators will notify the accredited ethics board of the end of the study within a period of 8 weeks.