Cryopreserved Platelets Fall Short in Cardiac Surgery Bleeding Control: CLIP-II Trial
Australia: Cryopreserved platelets, which can be stored for up to two years, did not demonstrate noninferior effectiveness compared with conventional liquid-stored platelets for controlling bleeding in cardiac surgery patients, according to results of the CLIP-II randomized clinical trial published in JAMA.
The study, led by Michael C. Reade from the Medical School at the University of Queensland, Brisbane, evaluated whether cryopreserved platelets could serve as a viable alternative to standard platelets, which have a shelf life of only five to seven days and are often subject to wastage.
The multicenter, double-blind, noninferiority trial was conducted across 11 tertiary hospitals in Australia between August 2021 and April 2024. Adults undergoing cardiac surgery who were considered at high risk of requiring platelet transfusion were eligible. Of 879 patients screened, 388 were randomized, and 202 ultimately received study platelets. Participants received up to three units of either group O dimethyl sulfoxide–cryopreserved platelets or standard liquid-stored platelets during surgery or within the first 24 postoperative hours.
The primary endpoint was chest drain blood loss within 24 hours of intensive care unit (ICU) admission. Noninferiority was defined as less than a 20% increase in bleeding compared with the liquid-stored platelet group. Among the 202 transfused patients (mean age 64.4 years; 75.7% male), 30.2% underwent nonelective surgery.
The following were the key findings:
- Median 24-hour postoperative blood loss was 605 mL in the cryopreserved platelet group compared with 535 mL in the liquid-stored platelet group.
- The difference in blood loss was not statistically significant (ratio of geometric means 1.13).
- The upper limit of the confidence interval exceeded the predefined 20% noninferiority margin, and noninferiority was therefore not established.
- Cryopreserved platelets were associated with significantly higher intraoperative blood loss (ratio of geometric means 1.42).
- Total perioperative blood loss was also greater in the cryopreserved group (ratio of geometric means 1.31).
- Patients receiving cryopreserved platelets required more transfusions of red blood cells, plasma, and cryoprecipitate.
- The incidence of prespecified adverse events was similar between the two groups.
- Median duration of mechanical ventilation was longer in the cryopreserved group (25.5 hours vs 23.6 hours).
- Intensive care unit stay (3.8 vs 3.0 days) and total hospital stay (10.9 vs 9.1 days) were longer among patients who received cryopreserved platelets.
The authors acknowledged several limitations. Findings in high-risk cardiac surgery patients may not apply to trauma, obstetric hemorrhage, or gastrointestinal bleeding. Differences in platelet preparation methods and potential partial unblinding could also have influenced outcomes. Nonetheless, the results consistently indicated lower hemostatic performance with cryopreserved platelets.
Overall, cryopreserved platelets did not meet the predefined criteria for noninferiority in managing surgical bleeding. Although they may still have a role in situations where liquid-stored platelets are unavailable—such as rural, military, or supply-limited settings—they should not replace conventional platelets when standard products are accessible.
Reference:
Reade MC, Marks DC, Howe BD, et al. Cryopreserved vs Liquid-Stored Platelets for the Treatment of Surgical Bleeding: The CLIP-II Randomized Noninferiority Clinical Trial. JAMA. 2026;335(7):600–608. doi:10.1001/jama.2025.23355
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