Background:

Platelet transfusion refractoriness (PTR), or inability to achieve an acceptable rise in platelet count following transfusion, is found in up to 30% of heavily transfused patients and is associated with increased bleeding, increased length of hospital stay, delayed or interrupted delivery of curative therapies such as chemotherapy and hematopoietic stem cell transplantation, and in select populations (e.g., acute leukemia or post-transplant), has been linked to inferior survival outcomes. Despite its frequency and clinical importance, current diagnostic and management practices remain inconsistent and fragmented across institutions. Although immune and non-immune pathways contribute to PTR, heterogeneity of tests utilized (e.g., corrected count increment [CCI], HLA antibody screen, flow cytometric crossmatch), intervention timing, and lack of standardized treatment algorithms make prompt diagnosis and best management practices difficult. There is an urgent need for an evidence-based, consolidated clinical algorithm that marshals current data and provides an algorithmic framework to hematologists, transfusion medicine specialists, and hospitalists, respectively.

Objective:

To review systematically the literature regarding diagnosis and management of PTR and to describe an available tiered clinical strategy allowing for immediate evaluation and individualized treatment, including HLA-matched and crossmatched platelets, immunosuppression, and non-transfusion hemostatic interventions.

Methods:

A systematic review was conducted using PubMed, EMBASE, Cochrane Library, and ClinicalTrials.gov per PRISMA 2020 guidelines. MeSH terms included “platelet transfusion refractoriness,” “alloimmunization,” “corrected count increment,” “HLA antibodies,” “platelet crossmatch,” and “HPA incompatibility.” Inclusion criteria were original studies, clinical trials, case series, and reviews in adult patients with hematologic malignancies or other chronic transfusion needs. Studies were independently screened and abstracted by two reviewers. Data extraction focused on: (1) diagnostic thresholds and timing of testing, (2) causes of refractoriness, (3) available diagnostic modalities, (4) response to interventions (e.g., HLA-selected platelets, IVIG, rituximab), and (5) patient-centered outcomes including bleeding risk and transfusion independence.

Results:

Out of 212 initial studies, 53 met inclusion criteria. The diagnostic workup was inconsistent in > 40% of reported cases, particularly regarding when to calculate CCI and which cutoff (CCI < 5,000–7,500 at 1–24 hours post-transfusion) to use. Immune-mediated causes, primarily anti-HLA and anti-HPA antibodies, were implicated in 20–30% of cases but were often identified late due to delays in testing. HLA-matched and crossmatch-compatible platelets showed variable efficacy across settings, with improved response rates (~50–70%) when implemented early. Novel modalities such as flow cytometric crossmatch and solid-phase assays were underutilized despite improved detection of alloantibodies. The non-immunological causes, such as fever, sepsis, splenomegaly, and DIC, were identified in > 50% of the cases but not provided with standardized evaluation. Very few studies showed combined diagnostic-to-treatment algorithms.

Suggested Framework:

We describe a tiered, time-dependent clinical algorithm involving platelet response count measures, standardized CCI determination, immunologic testing, and preemptive identification of non-immune determinants. Tiers are diagnosis and therapy:

Tier 1: Identification of PTR via two consecutive CCI < 7,500; exclusion of acute non-immune causes

Tier 2: Screening for alloantibodies (anti-HLA/HPA); referral to transfusion medicine

Tier 3: Escalation to HLA-matched or crossmatched platelets; consideration of immunosuppressive agents (e.g., IVIG, rituximab)

Tier 4: Management of chronic PTR and transfusion independence (e.g., TPO-RAs, antifibrinolytics, splenectomy in select cases)

Conclusion:

PTR remains an intractable and underdiagnosed complication in chronically transfused patients. Our systematic review points out key therapeutic and diagnostic gaps and recommends a consensus, tiered clinical algorithm. The system is designed to reduce diagnostic delay, make transfusion support more rational, and optimize bleeding outcomes. Further prospective validation in institutional and multicenter settings is warranted.

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2025
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