A Brief Overview of 7-day Platelets

The transfusion community has targeted platelets as the primary culprit in transfusion-associated clinical sepsis and fatal microbial infection. Platelets (PLTs) are associated with a higher risk of sepsis and related fatality than any other transfusable blood component. Concerns over bacterial contamination in PLT concentrates prompted the US Food and Drug Administration (FDA) in 1986 to issue a memorandum limiting the storage time of platelet products to 5 days. Only recently did the FDA issue draft guidance describing bacterial testing to improve the safety and availability of PLTs, and outlined the steps necessary for transfusion services to extend apheresis PLTs to 7 days.

Microbial infections were the 4th leading cause of transfusion-related mortality, accounting for 8% of them between 2010 and 2014. PLT storage at ambient room temperature supports high titer bacterial proliferation. Skin flora are the most common source of contamination, occurring at the time of collection. Despite the introduction of improved pre-collection arm preparation and analytically sensitive culture-based bacterial detection methods, the risk of fatal and non-fatal clinical sepsis has persisted.

Most recently, the 2016 AABB standards stated that PLTs may be stored for 7 days only if: 1) storage containers are cleared or approved by FDA for 7-day PLT storage and 2) labeled with the requirement to test every product stored beyond 5 days with a bacteria detection device cleared by FDA and labeled as a “safety measure.” The Verax PGD test is a rapid, single use, lateral flow immunoassay, and the only rapid, day of transfusion test the FDA has cleared as a “safety measure.” The proprietary test detects surface bacterial antigens, namely lipotechoic acid found on gram positive organisms and lipopolysaccharide found on gram negatives. The PGD test as a “safety measure” is to be used in concert with culture, not replace it.

Verax PGD test

Approximately 2.2 million PLT transfusions are administered yearly in the United States, of which more than 90% consist of apheresis PLTs. If the available data were generalized to the entire US apheresis PLT supply, approximately 650 contaminated apheresis PLTs would be caught with the PGD test, preventing septic transfusion reactions and potential fatalities each year. The FDA approval of this test allows non-culture based testing to extend dating from 5 to 7 days and further closes the safety gap that exists in apheresis PLTs.

 

Rogers

-Thomas S. Rogers, DO is a third-year resident at the University of Vermont Medical Center, a clinical instructor at the University of Vermont College of Medicine, and the assistant medical director of the Blood Bank and Transfusion Medicine service.

The author declares that he has no disclosures.

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