Faint and pre-faint reactions in whole blood donors: predictive value of pre-donation measurements

Background A small proportion of blood donors have adverse react-ions. The purpose of this study was to determine predictors of faint and significant hypotensive reactions that could serve as targets for interventions to reduce reactions, thus improving the blood donation experience for those at higher risk of reactions and reducing the risk of serious adverse events. Methods The records of 422,231 allogeneic whole blood donations from a 9-month period were assessed for adverse reactions. Incidents related to needle insertion, such as hematoma were excluded. Demographic, biometric, and clinical measurements were collected. Reactions were analyzed by multivariate logistic regression analysis comparing donors with any adverse reaction to donors without reactions and by stratified rates according to reaction severity. Results The overall reaction prevalence was 1.43%. Of the reactions, 63%, 29% and 8% were classified as mild, moderate and severe, respectively. Markers of reactions were: age, gender, race, blood volume, blood pressure, pulse and body mass index. Compared to donors without reactions, the strongest predictor of a reaction was a donor's blood volume <3500 ml (OR 2-9, 95% CI 2.57-3.23). Age and first time status were also associated with a significantly higher risk of reaction with 17-18 years olds (OR 2-8, 95% CI 2.59-2.98) and 19-24 year olds (OR 2.39, 95% CI 2.23-2.56) at higher risk compared to 25-65 year olds, and first time donors at higher risk compared to repeat donors (OR 2.2, 95% Cl 2.07-2.33). Using a lower weight limit of 50 kg does not prevent donors from giving more than 15% of their blood volume. Conclusion The results of this study are helpful in identifying donors at risk for adverse reactions and in understanding the contributors to reactions. Donor blood volume was a strong predictor of reaction. Selecting donors using blood volume, not weight, should reduce the frequency of reactions.