New international guidelines from the Association for the Advancement of Blood and Biotherapies and the International Collaboration for Transfusion Medicine Guidelines endorsed restrictive platelet transfusion thresholds across multiple patient populations.

The recommendations were based on a systematic review and meta-analysis of 21 randomized controlled trials and 13 observational studies that involved more than 4,800 participants, according to the guideline authors.

Restrictive strategies showed little or no difference in all-cause mortality compared with liberal strategies: The absolute risk difference (ARD) was −0.4%. Rates of grade 3 to 4 bleeding were also similar (ARD = 0.3%).

"Restrictive strategies reduce risk of adverse reactions, mitigate platelet shortages, and reduce costs," noted author Ryan A. Metcalf, MD, of the Department of Pathology at the University of Utah, Salt Lake City.

Four strong recommendations were issued based on high- to moderate-certainty evidence:

• In nonbleeding patients with hypoproliferative thrombocytopenia receiving chemotherapy or undergoing allogeneic stem cell transplant, transfusion was recommended when platelet count was below 10 × 10³/μL.

• In neonates with consumptive thrombocytopenia but without major bleeding, the recommended threshold was below 25 × 10³/μL.

• In patients undergoing lumbar puncture, transfusion was advised when platelet count was below 20 × 10³/μL.

• In patients with Dengue-related consumptive thrombocytopenia without major bleeding, transfusion was not recommended.

Spinal hematoma incidence following lumbar puncture remained low even at low platelet counts. Observational data indicated an incidence of 0.8 per 1,000 procedures when platelet counts were below 50 × 10³/μL.

Conditional recommendations, which were supported by low or very low-certainty evidence, were made for other populations, including patients undergoing autologous stem cell transplant, those with critical illness-related thrombocytopenia, and patients undergoing invasive procedures. For interventional radiology, transfusion was recommended when the count was below 20 × 10³/μL for low-risk procedures and 50 × 10³/μL for high-risk procedures.

In patients undergoing cardiovascular surgery without major hemorrhage, including those on cardiopulmonary bypass, transfusion was not recommended regardless of platelet count. Similarly, transfusion was not advised for nonoperative intracranial hemorrhage when platelet counts exceeded 100 × 10³/μL.

Adverse event rates associated with platelet transfusions included febrile nonhemolytic reactions (1 to 10 per 1,000 transfusions), allergic reactions (10 to 30 per 1,000), and transfusion-associated circulatory overload (6.6 per 1,000). These risks informed the rationale behind more conservative use.

Recommendations were developed using Grading of Recommendations Assessment, Development, and Evaluation methodology and incorporated outcome certainty and patient-centered values such as quality of life, risk reduction, and cost containment. 

While trial definitions of “restrictive” varied, the panel concluded that restrictive strategies could be safely implemented across settings. Individual clinical context—including bleeding history, signs and symptoms, laboratory parameters, and patient preferences—should guide transfusion decisions.

A full list of author disclosures can be found online.

Source: JAMA