Mechanisms of allergic transfusion reactions (ATRs) are not well understood. The aim of this study was to distinguish recipient, donor, and product-specific factors associated with ATRs.
Study Design and Methods
We conducted a retrospective cohort study of apheresis platelet (AP) products transfused from 4/2000–3/2010. The concordance rate of ATRs when split AP products were transfused to ≥2 individuals was compared to the overall ATR rate among all AP products. Per person ATR rates also were compared to the overall ATR rate.
We observed 1,616 ATRs among 93,737 transfusions, for an overall incidence of 1.72%(95%CI: 1.64–1.81%). Of the 1,616 ATRs, 630 occurred when split AP products were transfused to ≥2 recipients. Of these 630 AP products, ATRs were observed in ≥2 different recipients of the same AP collection only 6/630 times, for a concordant incidence of 0.95% (95% CI: 0.35–2.06%), which is similar to the overall ATR rate (P=0.17). On an individual level, 30.0% of recipients had ATR rates >5%, and these 30.0% accounted for 62.1% of ATRs. Donors of AP products associated with concordant ATRs donated AP products that had an ATR rate of 5.8% (95% CI 3.1–9.7%), which is higher than the overall ATR rate (P<0.001).
An observed ATR does not predict an ATR in a different recipient of a split AP product. A minority of platelet recipients accounts for the majority of ATRs. Some donors are strongly associated with ATRs. Consequently, recipient and donor factors are implicated in the mechanism of ATRs.