1Department of Pathology, University of Pittsburgh, Pittsburgh, PA, USA.
2Department of Clinical Immunology, Odense University Hospital, Odense C, Denmark.
3The Institute for Transfusion Medicine, Pittsburgh, PA, USA.
Volunteer donors fulfilling current Danish eligibility criteria underwent WB and/or plasmapheresis donations at the main hospital donor site, while whole blood donations were also collected at a five-bed satellite facility of the hospital. Pre-donation vital signs were recorded by the same donor center staff, who supervised plasma and WB donations at both sites. Apheresis plasma donations were collected using the PCS2 plasma collection system (Haemonetics Corporation, Braintree, MA, USA); 700 mL of plasma were collected if the donor's body weight was greater than 70 kg and 600 mL if the weight was between 60–70 kg. The minimum body weight for WB donors was 50 kg. Donor demographics, details of the collection procedure and complications related to the collection procedure from January 2, 2014 to August 10, 2016 at the Odense University Hospital were reviewed from the donation database (ProSang, Databyran AB, Stockholm, Sweden). Tests of normality were performed for continuous variables and the appropriate descriptive statistics were calculated. The Chi-squared test was used to compare the differences between dichotomous variables, a Wilcoxon rank-sum test was used to compare the mean rank between groups for non-normally distributed continuous variables and a two-sample test of proportions was used to compare re-donation rates amongst donors with or without the experience of VVR. A multivariate logistic regression, clustered by unique donor, was performed using VVRs as the dependent variable and age group, gender, donation type, donation site, donation number, season and donation volume as independent variables (Stata version 14, StataCorp, TX, USA).
There were 54,542 donations (56.6% WB and 43.4% apheresis plasma donations) during the study period from 11,912 individual WB donors and 4,840 individual apheresis plasma donors (4,164 donors donated both WB and apheresis plasma). Donor demographics are shown in Table 1. During the study period there were 353 VVRs in 336 unique donors of which three donors who donated both WB and apheresis plasma experienced VVRs with both donation types. Two WB donors experienced two VVRs and 12 apheresis plasma donors experienced two VVRs. Although quite low overall, the VVR rate was almost 3 times higher in the apheresis plasma donor group compared to WB donors, perhaps due to the longer procedure time and extra-corporeal volume or fluid shifts during apheresis (Table 1).
Analysis of the demographics for WB donors showed that the VVR rate was not different between male and female donors (
Analysis of the demographics for apheresis plasma donors showed that female donors experienced twice the rate of VVRs compared to male donors (mean VVR rates of 1.54% vs. 0.75%, respectively,
In terms of environmental factors, the VVR rate for WB donations was low but was significantly higher at the satellite facility compared to the main hospital site (0.57% vs. 0.30%,
Comparing donation volume, the VVR rate was 11% in WB donations with a volume less than 405 mL, possibly due to the adverse event during the process, compared to 0.07% in donations with a volume between 405–495 mL (
Almost 90% of all VVRs occurred during the first two donations for WB donors and almost 75% of VVRs occurred during the first three apheresis plasma donations. Fig. 2 shows that the VVR rate was the highest on donation number one for both WB and apheresis plasma donations (dashed lines). The re-donation rate was three-fold lower in WB donors (21.7% vs. 65.8%) and two-fold lower (38.2% vs. 80.9%) in apheresis plasma donors with experience of VVR compared to donors without VVR (
The results of the clustered multivariate regression model are shown in Table 2. Apheresis plasma donors had higher odds ratio for experiencing a VVR compared to WB donors. Female donors also had a higher likelihood of experiencing a VVR compared to male donors. The odds ratio for experiencing a VVR decreased with increasing age and with higher donation numbers. The main hospital donation site was associated with a lower odds ratio for having a VVR compared to the satellite collection facility but the odds ratio for a seasonal effect was not significant.
The analysis performed in this study was limited to the variables captured in the donation registry, and as such, the inability to account for the effect of factors such as donor weight, ethnicity, first-time donation status, history of VVRs, waiting time, time since last meal and pre-donation psychometric variables is potentially a limitation. Additionally, not all of the donation-related parameters were available for all the donations included in the study. Nonetheless, this study confirms the findings of prior studies that younger age and female gender are associated with a higher rate of VVR, regardless of the donation type. The majority of VVRs occurred on the first documented donation in the study period and there was a significantly lower redonation rate after a VVR event for both WB and apheresis plasma donors. The unexpected finding of a higher VVR rate associated with an apheresis donation volume of 550–650 mL versus 650–750 mL is likely because the volume collected for apheresis donations was based on donor weight and donors with lower weight have a higher reported rate of VVRs, and/or that the occurrence of a VVR caused the premature termination of the collection . These findings highlight the importance of identifying risk factors for donor VVRs in order to take steps to mitigate these reactions and thereby encourage re- donations. Donors identified to be at risk of VVR should be monitored more closely in order to improve the donor experience. Donor hemovigilance registries should collect data on additional parameters potentially associated with VVRs.
Vasovagal reaction (VVR) rate stratified by donation type, age group and gender. The average VVR rate was not different between males and females for whole blood donations (<=0.490), but there was a trend towards a higher rate of VVRs in male whole blood donors less than 30 years of age (43/5,030 for males vs. 40/6,233 for females, <=0.192) and female donors greater than 30 years of age (11/11,370 for males vs. 14/8,127 for females, <=0.147). Female apheresis plasma donors experienced a mean VVR rate that was twice as high compared to male plasma donors (
Number and rate of vasovagal reactions (VVRs) stratified by donation number. The solid bars represent the number of VVRs that occurred on each donation number. The dashed line represents the rate of VVRs expressed by donation number for all donors; for example, the rate of VVRs on the first donation recorded for all donors in the registry was 0.6% for whole blood and 2.1% for apheresis plasma donations. The majority of VVRs occurred during the first two donations in the whole blood group and during the first three donations in the apheresis plasma group. No VVR occurred after donation number five in the whole blood group, whereas 33 VVRs occurred during donation numbers six and twenty-one in the apheresis plasma group.