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.