Impact of Elevated Hemoglobin and Serum Protein on Vasovagal Reaction from Blood Donation.

We conducted a cross-sectional study to elucidate factors contributing to vasovagal reaction (VVR), the most frequent side effect following whole blood and apheresis donations. Complications recorded at the collection sites after voluntary donations by the Japanese Red Cross Tokyo Blood Center (JRC), in the 2006 and 2007 fiscal years, were analyzed by both univariate analysis and the multivariate conditional logistic regression model. Of 1,119,716 blood donations over the full two years, complications were recorded for 13,320 donations (1.18%), among which 67% were VVR. There were 4,303 VVR cases which had sufficient information and could be used for this study. For each VVR case, two sex- and age-matched controls (n = 8,606) were randomly selected from the donors without complications. Age, sex, body mass index (BMI), predonation blood pressure, pulse and blood test results, including total protein, albumin, and hemoglobin, were compared between the VVR group and the control group. In univariate analysis, the VVR group was significantly younger, with a lower BMI, higher blood pressure and higher blood protein and hemoglobin levels than the control group (p<0.001). Furthermore, blood protein and hemoglobin levels showed dose-dependent relationships with VVR incidences by the Cochran-Armitage trend test (p<0.01). For both sexes, after adjusting for confounders with the multivariate conditional logistic regression model, the higher than median groups for total protein (male: OR 1.97; 95%CI 1.76,-2.21; female: OR 2.29; 95%CI 2.05-2.56), albumin (male: 1.75; 1.55-1.96; female: 1.76; 1.57-1.97) and hemoglobin (male: 1.98; 1.76-2.22; female: 1.62; 1.45-1.81) had statistically significant higher risk of VVR compared to the lower than median groups. These elevated serum protein and hemoglobin levels might offer new indicators to help understand VVR occurrence.