Cold-Stored Platelets Noninferior to Conventional Platelets in Cardiac Surgery

Platelets stored at 1-6 degrees Celsius for up to 21 days are noninferior to conventional room-temperature platelets for controlling active bleeding in patients undergoing cardiac surgery, according to new research published in JAMA. The investigators said the findings could extend platelet availability, reduce wastage and make it more feasible for hospitals to maintain platelet inventories for patients with severe bleeding.

The phase 3 trial, led by researchers at the University of Pittsburgh, enrolled 1,000 pediatric and adult patients undergoing complex cardiac surgery with cardiopulmonary bypass at 27 sites in the United States and Australia between December 2021 and March 2025. Patients were randomized 2:1 to receive cold-stored platelets (CSPs) (up to 21 days) or room-temperature platelets (up to seven days). Of the 1,000 patients who received platelets, 989 were included in the primary analysis.

The primary outcome was a five-point hemostatic efficacy score, with higher values indicating more bleeding. The trial used a noninferiority margin of one point and an adaptive design that allowed investigators to increase the maximum storage duration of CSPs at planned interim analyses if the treatment continued to meet the prespecified noninferiority criterion.

Investigators found that CSPs were noninferior across every storage duration studied, including 21 days, with a posterior probability of noninferiority exceeding 99.9%. Pooled across storage durations, the mean hemostatic efficacy score was 3.08 for CSPs compared with 2.99 for room-temperature platelets. The secondary outcome, 24-hour chest tube output, did not differ meaningfully between groups. No cold-storage duration demonstrated superiority to room-temperature platelets.

There were no significant differences between groups in thrombotic events, transfusion-associated adverse events, kidney failure, septic shock or mortality. However, patients who received CSPs had a higher rate of reexploration for bleeding within 24 hours (4.2% versus 1.8%) and received more total blood products at 24 and 72 hours.

Platelet count increments after transfusion also were smaller with CSPs. The authors offered several possible explanations, including faster clearance of CSPs from circulation or greater incorporation into clots at bleeding sites, but noted that the possibility that CSPs were somewhat less hemostatically effective cannot be ruled out.

The authors noted several limitations, including the lack of standardized indications for platelet transfusion, use of both cold- and room-temperature platelets in a subset of patients, and lack of separate validation for the modified hemostatic efficacy score used for lower-weight patients.

The investigators said a longer shelf life could ease pressure on the platelet supply, which faces challenges related to the length of the donation process, an aging donor base and the short shelf life of room-temperature platelets.

“Rural and community hospitals, for the most part, simply cannot justify keeping room temperature platelets in stock. They don’t see enough severely bleeding patients, so the waste would far exceed the benefit, something our nation’s fragile blood supply chain cannot accommodate,” said Michael Boisen, MD, the study’s co-author and principal investigator for UPMC’s CHIPS trial site. “So, if we can safely extend the shelf life of platelets and reduce the waste, imagine how many more people we could help.”