Platelet activation status can have a significant impact on the clinical outcome of a platelet transfusion. This is most clearly seen when looking at metrics that consider the entire transfusion history of multiple patients; as summarized in this post examining the relationship between platelet activation and platelet utilization.

Platelet activation rate is the percentage of platelet units in an inventory that are classified as activated. In a previous post, we examined platelet activation rates of hospitals across the US. To further the understanding of platelet activation, we investigated the variability in the platelet activation rates of different suppliers across the US. We also looked at the variability in activation rates over time of two suppliers to determine how activation rates vary with time. Below are the platelet activation rates from 5 US suppliers. They include a large national supplier, community and regional blood banks, and a hospital-based donor clinic.

These rates are the absolute activation rates observed after the platelets were received at the hospital blood banks. Based on our experience the primary source of platelet activation is the donor themselves, however, the apheresis system used in collection and other stressors such as transportation, aging, and additional processing may all contribute to overall platelet activation.

For Suppliers A and B, we examined the activation rates over time. Platelet activation status was measured for five months in a hospital that receives platelets from a national platelet supplier (Supplier A) and produces a significant number of platelets in-house (Supplier B). In each of the five months, the national supplier (Supplier A) provided more activated platelets than the in-house donor clinic.

The daily activation rates reveal surprising results. Both suppliers had days where 100% of platelets supplied were activated and other days where 100% of platelets supplied were non-activated. However, Supplier B only had two days in the five months where they provided exclusively activated platelets, compared to five days from Supplier A.

The larger red area in Supplier A’s time graph demonstrates that they supplied a higher proportion of activated platelets, though there were occasional days where Supplier B delivered more activated platelet units than Supplier A. There are many factors that impact platelet activation which will be discussed in a future post. A plausible explanation for the daily variation seen above is the large variation in platelet activation among donors and within the same donor across multiple donations. Inter-donor variations carry additional weight as multiple unit donations tend to be shipped together. These multiple unit donations result in an increased impact of individual donors on the activation rate of a particular day.

This data set is only the start of truly understanding the difference in activation rate among platelet suppliers and how this rate changes over time. Further work needs to be done to understand the specific causes of platelet activation and to determine the source of the differences in activation rate among platelet suppliers.