By Betty T. Tran, MD, MSc
Assistant Professor of Medicine, Pulmonary and Critical Care Medicine, Rush University Medical Center, Chicago
This article was edited by David J. Pierson and peer reviewed by William Thompson, MD. Dr. Pierson is Professor Emeritus, Pulmonary and Critical Care Medicine, University of Washington, Seattle, and Dr. Thompson is Associate Professor of Medicine, University of Washington, Seattle.
SYNOPSIS: Based on a recent systematic review of the literature, clinical guidelines were developed by the American Association of Blood Banks with the goal of providing platelet transfusion thresholds for adult patients in common clinical scenarios.
SOURCE: Kaufman RM, et al. Platelet transfusion: A clinical practice guideline from the AABB. Ann Intern Med 2014 Nov 11 [Epub ahead of print].
The American Association of Blood Banks (AABB) commissioned a panel of 21 experts to develop guidelines on the appropriate administration of platelet transfusion in adult patients based on the best available published evidence. The guidelines were based on a recent systematic review of the literature searching PubMed from 1946 to September 2014 and the Cochrane Central Register of Controlled Trials and Web of Science from 1900 to September 2014. Seventeen randomized, controlled trials and 53 observational studies were included in the final review. The authors aimed to identify platelet thresholds in common clinical situations at which prophylactic platelet transfusion would likely improve hemostasis and benefit the patient.
In summary, the AABB had six recommendations of varying strengths based on the availability of quality evidence. The AABB recommends the prophylactic transfusion of platelets in the following clinical scenarios:
Hospitalized adults with therapy-induced hypoproliferative thrombocytopenia with a platelet count of <= 10 x 109 cells/L (10,000 cells/μL) to reduce the risk of spontaneous hemorrhage. Low-dose platelet transfusions (equal to one-half a standard apharesis unit) are equally effective in decreasing bleeding risk but require more frequent transfusions; however, high-dose platelet transfusions (double the standard dose) do not provide additional hemostatic benefit (quality of evidence: moderate, strength of recommendation: strong).
Patients having elective central venous catheter (CVC) placement with a platelet count < 20 x 109 cells/L (20,000 cells/μL) (quality of evidence: low, strength of recommendation: weak).
Patients having elective diagnostic lumbar puncture (LP) with a platelet count < 50 x 109 cells/L (50,000 cells/μL) (quality of evidence: very low, strength of recommendation: weak).
Patients having major elective non-neuraxial surgery with a platelet count < 50 x 109 cells/L (50,000 cells/μL) (quality of evidence: very low, strength of recommendation: weak).
The last two recommendations focus on clinical scenarios in which the AABB does not recommend routine prophylactic platelet transfusion:
The AABB recommends against routine prophylactic platelet transfusion for patients who are nonthrombocytopenic and have cardiac surgery with cardiopulmonary bypass. Transfusion is suggested if these patients exhibit perioperative bleeding with thrombocytopenia and/or evidence of platelet dysfunction (quality of evidence: very low, strength of recommendation: weak).
The AABB cannot recommend for or against platelet transfusion in patients receiving antiplatelet therapy who have traumatic or spontaneous intracranial hemorrhage (quality of evidence: very low, strength of recommendation: uncertain).
Given that most platelet transfusions are ordered prophylactically to reduce the risk of bleeding in patients with hematopoietic disorders and/or prior to invasive procedures, these recommendations are a helpful guide in managing thrombocytopenia in commonly encountered clinical scenarios. The authors duly note that these guidelines are not meant to be universal standards of care; clinical scenarios can be quite complex, and platelet counts are not representative of platelet function. Development of these guidelines highlights the need for further investigation in this field, as data are limited beyond the indication for prophylaxis against spontaneous hemorrhage in patients with hypoproliferative thrombocytopenia (recommendation #1). The AABB recommendations are mostly based on observational data, often from a single center’s experience, and, thus, rely heavily on the panel’s expert interpretation and consensus (or lack thereof) on the topic. Although this can result in more biased data, one can envision the potential ethical challenges of doing randomized trials involving prophylactic platelet transfusions prior to procedures. It is reassuring, however, that severe or life-threatening bleeding complications (WHO modified bleeding scale grade 3 or 4) are quite rare in the setting of invasive procedures such as CVC placement or LP. Therefore, the higher platelet transfusion recommendations for interventions involving the central nervous system (< 50,000 cells/μL for LP, < 80,000-100,000 cells/μL for surgeries traditionally) are largely based on the potential for devastating neurologic complications as a result of bleeding rather than actual observed outcomes.