Researchers in Japan published a paper in Vox Sanguinis that described the development of a scoring system for blood donors that could be used as a vasovagal reactions (VVR) prediction tool. The authors explained that the scoring system included, “registration information such as donor status, age, and estimated blood volume (EBV).” The paper also noted, “pre-syncopal and syncopal symptoms as well as on- and off-site reactions.” The researchers categorized donor status into, “four groups: first-time donors (FT), repeat donors with no history of VVR (Rep 0), repeat donors with a history of one episode of VVR (Rep 1), and repeat donors with a history of two or more episodes of VVR (rep 2).”
The two datasets of study participants for the vasovagal reactions prediction tool either presented to donate whole blood between January and December 2019 (n=361,114) or between January and August 2020 (n=216,211). The authors explained that whole blood donations in Japan consist of either 200 mL or 400 mL, but the former were not eligible for the study, “because they were fewer and less likely to develop [a] VVR than those requesting 400 mL whole blood donation.” They described donor characteristics captured from the database as, “age, sex, body weight and height, systolic blood pressure (sBP), diastolic blood pressure (dBP), pulse rate (PR), donation history (first-time or repeat), sleeping and fasting time, number of VVR experiences in past donations, and donation site (mobile or fixed). Height, weight, and sleeping time were self-reported by the donors at the time of donation. Fasting time was calculated by subtracting the self-reported last mealtime from the start time of blood collection. sBP, dBP, and PR were measured before blood collection using fully automated sphygmomanometers.”
For this study of the vasovagal reactions prediction tool, the researchers defined a VVR occurrence as, “general feeling of discomfort and weak-ness with anxiety, dizziness, and nausea related to blood donation, which may progress to loss of consciousness. The presence of [a] VVR was confirmed by the blood collection staff on the basis of symptoms and vital signs. Off-site reactions were recorded only if the donors notified [the blood center] voluntarily.”
Both pre-syncopal symptoms and syncopal reactions were considered a VVR in this study of the vasovagal reactions prediction tool. “Permutation variable importance (PVIMP) [was] defined as the decrease in the prediction performance of a model when the value of a single variable is randomly shuffled.” The authors explained that, “PVIMP showed that the most important variable was the donor status, followed (in order) by age, EBV, height, sBP, SI, dBP, PR, sex, donation site, fasting time and sleeping time.”
The study of the vasovagal reactions prediction tool found that while donor status and age were the most important variables, that also a, “positive systematic linear relationship [existed] between the two variables, with higher scores indicating a higher incidence of VVR (p for trend <.001)…Overall, VVR occurred in 0.50 percent of donors. VVR rates in groups with scores of 0, 1, 2, 3, 4 and 5 or more were 0.09 percent (95 percent CI: 0.081 percent–0.10 percent), 0.33 percent (95 percent CI: 0.31 percent–0.36 percent), 0.87 percent (95 percent CI: 0.78 per-cent–0.96 percent), 1.17 percent (95 percent CI: 1.05 percent–1.30 percent), 2.15 percent (95 percent CI: 1.98 percent–2.32 percent), and 3.11 percent (95 percent CI: 2.90 percent–3.34 percent), respectively.”
The researchers who developed the vasovagal reactions prediction tool concluded that, “donor status was identified as the most important risk factor for VVR, and first-time donation and previous donation reactions equally influenced VVR. The importance of the first-time donor status is well-established…Age was the next most important variable for VVR. Unexpectedly, we found that sex was not an important variable compared with donor status, age, and EBV…Our finding suggests that upon whole blood donation, height may replace sex as a risk factor for VVR; otherwise, our EBV formula needs to be corrected by height for VVR estimation. We may also need to devise a new EBV formula, especially for Asian populations, reflecting height more efficiently.” Limitations of their research included that the scoring system was created using data from a single blood center and, “it is important to analy[z]e reactions across the time-course of blood donation; however, owing to the limited number of samples of off-site reactions, we were unable to analy[z]e them separate-ly.”
Citation: Hashizume, T., Kondo, G., Ishimaru, F., et al. “Development and validation of a scoring system to predict vasovagal reaction upon whole-blood donation.” Vox Sanguinis. 2023