The relationship between blood test results and vasovagal reactions: An intra-individual comparative retrospective analysis of blood donor data in Japan

Background and Objectives: To determine whether intra-individual differences in pre-donation blood test results were associated with vasovagal reactions (VVRs). Materials and Methods: The study included donors who voluntarily donated 400 mL of whole blood at least twice during a 5-year blood collection period of the Japanese Red Cross, including both donations with and without a VVR. A conditional logistic regression analysis by age group and sex was conducted, using each donor as a stratum, together with an analysis of deviance to test the significance of including an interaction term between age group and blood data in the regression model. Results: A total of 1873 donors were included in the analysis. Haemoglobin, haematocrit, total protein and albumin values prior to donation were higher when a VVR was observed than when it was not for each age group and sex. The regression analysis showed significant positive associations between each of these blood parameters and VVR in all combinations of age groups and sex. A particularly strong positive association between haemoglobin and VVRs is seen in women aged ≥50 years (odds ratio, OR [95% confidence interval, CI]: 1.844 [1.457, 2.333]). Conclusion: Haemoglobin, haematocrit, total protein and albumin levels within individual donors were significantly higher at donation with a VVR. This was most notable in women aged ≥50 years. Comparing the pre-donation haemoglobin value with past values in the same donor at the donation site would help raise awareness of the risk of VVRs.