New randomised trial data support the use of cold-stored platelets to treat active bleeding during cardiac surgery, potentially helping to increase platelet shelf-life and widen accessibility for transfusions, investigators say.
“Our findings could result in major international public health benefits,” said Philip Spinella (University of Pittsburgh, Pittsburgh, USA), lead author of the CHIPS study, findings of which were published this week in the Journal of the American Medical Association (JAMA). “This is incredibly transformative and will dramatically improve the availability of platelets while also reducing waste, allowing hospitals that aren’t in major cities to afford to keep this life-saving blood product on hand for bleeding patients.”
The study, a non-inferiority randomised clinical trial, sought to determine the maximum cold-storage duration—up to 21 days—for which cold-stored platelets are non-inferior or superior in haemostatic efficacy to room temperature platelets when transfused in actively bleeding patients undergoing cardiac surgery with cardiopulmonary bypass.
Currently, donated platelets are conventionally stored at room temperature with a five-to-seven-day shelf life, based upon the findings of studies conducted over half a century ago in healthy volunteers that led regulators to believe that refrigerating platelets to extend their shelf life made them less effective.
Recent in vitro and animal data suggest that cold-stored platelets kept for seven to 14 days may be superior in haemostatic function for patients with active bleeding and that those stored for 21 days may have similar haemostatic potential compared with room temperature platelets stored for five to seven days.
Spinella and colleagues designed CHIPS to safely test using refrigerated platelets stored for increasing amounts of time, enrolling 1,000 paediatric and adult patients undergoing cardiac surgery at 27 sites in the USA and Australia from December 2021 to March 2025.
Patients were randomised to receive either standard, room-temperature platelets stored for less than seven days or chilled platelets. At every 200 participants treated, independent data analysts looked at the results. If the chilled platelets were performing just as well as room-temperature, they would add up to another five days to the age of the chilled platelets used and enrol another 200 participants, up to a maximum of 21 days.
The study’s primary outcome was a five-level ordinal haemostatic efficacy score adapted from the universal definition for perioperative bleeding score, with values ranging from one to five and higher values indicating greater bleeding.
The research team saw that platelets refrigerated for up to three weeks were just as effective at treating bleeding as room temperature platelets stored for up to one week, finding that cold-stored platelets were non-inferior to room-temperature platelets, with a mean difference of 0.09 (95% credible interval, –0.06 to 0.23), exceeding the preset non-inferiority criterion.
Since it can take two days for blood banks to process donations, the finding holds the potential to extend the lifespan of platelets for use in controlling bleeding by almost four-fold, the researchers suggest.
“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 co-author Michael Boisen (University of Pittsburgh, Pittsburgh, USA). “So, if we can safely extend the shelf life of platelets and reduce the waste—imagine how many more people we could help.”
In an accompanying editorial in JAMA, Anthony Estrera and Charles Miller (both McGovern Medical School at UTHealth Houston, Houston, USA) write that the findings challenge a storage paradigm “that has remained largely unchanged for five decades”.
“The overall message is clear: refrigerated platelets retained clinical effectiveness for managing haemostasis in cardiac surgery patients, despite storage periods nearly three times longer than conventional room-temperature platelets,” they write.
“Ultimately, the CHIPS trial provides the strongest clinical evidence to date that cold-stored platelets can be used safely and effectively in actively bleeding cardiac surgical patients while dramatically extending storage duration. For transfusion services and blood banks, this may translate into fewer shortages, less waste, improved inventory flexibility, and broader platelet availability. More broadly, CHIPS demonstrates that adapting a treatment approach from one use case to another—from preservation of platelet function to acute haemostasis—should not be widely implemented in clinical practice without randomised clinical trials.”
