The threshold for prophylactic platelet transfusions in adults with acute myeloid leukemia. Gruppo Italiano Malattie Ematologiche Maligne dell'Adulto

Dose of prophylactic platelet transfusions and prevention of hemorrhage

BACKGROUND

We conducted a trial of prophylactic platelet transfusions to evaluate the effect of platelet dose on bleeding in patients with hypoproliferative thrombocytopenia.

METHODS

We randomly assigned hospitalized patients undergoing hematopoietic stem-cell transplantation or chemotherapy for hematologic cancers or solid tumors to receive prophylactic platelet transfusions at a low dose, a medium dose, or a high dose (1.1x10(11), 2.2x10(11), or 4.4x10(11) platelets per square meter of body-surface area, respectively), when morning platelet counts were 10,000 per cubic millimeter or lower. Clinical signs of bleeding were assessed daily. The primary end point was bleeding of grade 2 or higher (as defined on the basis of World Health Organization criteria).

RESULTS

In the 1272 patients who received at least one platelet transfusion, the primary end point was observed in 71%, 69%, and 70% of the patients in the low-dose group, the medium-dose group, and the high-dose group, respectively (differences were not significant). The incidences of higher grades of bleeding, and other adverse events, were similar among the three groups. The median number of platelets transfused was significantly lower in the low-dose group (9.25x10(11)) than in the medium-dose group (11.25x10(11)) or the high-dose group (19.63x10(11)) (P=0.002 for low vs. medium, P<0.001 for high vs. low and high vs. medium), but the median number of platelet transfusions given was significantly higher in the low-dose group (five, vs. three in the medium-dose and three in the high-dose group; P<0.001 for low vs. medium and low vs. high). Bleeding occurred on 25% of the study days on which morning platelet counts were 5000 per cubic millimeter or lower, as compared with 17% of study days on which platelet counts were 6000 to 80,000 per cubic millimeter (P<0.001).

CONCLUSIONS

Low doses of platelets administered as a prophylactic transfusion led to a decreased number of platelets transfused per patient but an increased number of transfusions given. At doses between 1.1x10(11) and 4.4x10(11) platelets per square meter, the number of platelets in the prophylactic transfusion had no effect on the incidence of bleeding. (ClinicalTrials.gov number, NCT00128713.)

Platelet transfusions: trigger, dose, benefits, and risks

Over the last half century, platelet transfusion has been an effective therapy for the prevention and treatment of bleeding, particularly in patients with hematologic malignancies. Recent randomized trials have demonstrated that current practices may be suboptimal in a number of ways. The rationale for parsimony in the use of this powerful therapy includes previously described severe and fatal adverse outcomes (including refractoriness, hemolysis from ABO-mismatched transfusions, acute lung injury, and bacterial sepsis), newly described serious potential risks (including thrombosis and earlier leukemic recurrence), difficulty in maintaining adequate supplies of platelets, the need to place volunteer donors on cell separators to provide the product, and cost. Recent findings demonstrate that the platelet count threshold for prophylactic transfusion can be as low as 10,000/µL, and a therapeutic rather than a prophylactic strategy of transfusion for bleeding manifestations only may be equally safe for most patients. Another recently completed study suggests that very low doses of platelet transfusions (the equivalent of half a unit of apheresis platelets or two to three units of whole blood-derived platelets) are as effective at preventing bleeding as much higher doses. One question for which there are no randomized trial data is at what threshold prophylactic platelet transfusion should be given before invasive procedures or major surgery. The typically recommended threshold of 50,000/µL is based only on expert opinion, and substantial observational data indicate that this threshold leads to many transfusions that are likely unnecessary and therefore represent risk with little or no additional benefit.

Diagnosis and management of acute myeloid leukemia in adults: recommendations from an international expert panel, on behalf of the European LeukemiaNet

In 2003, an international working group last reported on recommendations for diagnosis, response assessment, and treatment outcomes in acute myeloid leukemia (AML). Since that time, considerable progress has been made in elucidating the molecular pathogenesis of the disease that has resulted in the identification of new diagnostic and prognostic markers. Furthermore, therapies are now being developed that target disease-associated molecular defects. Recent developments prompted an international expert panel to provide updated evidence- and expert opinion–based recommendations for the diagnosis and management of AML, that contain both minimal requirements for general practice as well as standards for clinical trials. A new standardized reporting system for correlation of cytogenetic and molecular genetic data with clinical data is proposed.

Coagulopathy in critically ill patients: part 1: platelet disorders

Abnormalities of platelet number and function are the most common coagulation disorders seen among ICU patients. This article reviews the most frequent causes of thrombocytopenia by providing an overview of the following most common mechanisms: impaired production; sequestration; dilution; and destruction. Guidelines for treating thrombocytopenia and platelet dysfunction are also provided.

Novel and unexpected clearance mechanisms for cold platelets

Storage at room temperature is limited to 5 days because of the risk of bacterial growth and loss of platelet functionality. Platelet refrigeration remains impossible, because once chilled, platelets are rapidly removed from circulation. Chilling platelets (<4h) clusters glycoprotein (GP) Ibalpha receptors, and beta(2) integrins on hepatic macrophages recognize clustered beta GlcNAc residues leading to rapid clearance of acutely chilled platelets. Prolonged refrigeration increases the exposure of galactose residues such that, unexpectedly, hepatocytes remove platelets using their asialoglycoprotein receptors. Here we review current knowledge of the mechanisms of platelet removal, the existing knowledge of refrigerated platelet function, and methods to preserve platelet concentrates long-term for transfusion.

Gastrointestinal bleeding in the cancer patient

Gastrointestinal bleeding is a common occurrence in patients with cancer and is a frequent indicator of a gastrointestinal malignancy. Rapid evaluation and treatment is key for the hemodynamically unstable patient. Endoscopy remains the cornerstone of diagnosis and management for cancer patients with gastrointestinal bleeding. The emergency physician should also be aware of other diagnostic and treatment modalities that may be needed to take care of these patients.

Hemorrhagic complications in patients with advanced hematological malignancies followed at home: an Italian experience

Patients with advanced hematological malignancies may experience many troublesome hemorrhagic complications requiring hospitalisation during a palliative home care (HC) program. We report on the feasibility of the management of bleeding at home in patients with haematological malignancies admitted in a domiciliary HC program. The occurrence of a major hemorrhage episode (>1 WHO grade) was registered among 469 patients with hematological malignancies in the terminal phase of their disease followed at home. Number, sites, domiciliary treatment (local hemostatic measures, platelet units, hemostatic drugs, packed red blood cells) and outcome of hemorrhagic complications were evaluated. Out of 469 patients, 123 (26%) experienced a bleeding complication; the overall number of hemorrhagic episodes was 232 (49%) with a median number of 2 episodes per patient. Patients with a platelet count lower than 20 x 10(9)/L (P < 0.00005) or with a diagnosis of acute leukemia or in blast crisis of myeloprolypherative disorders (P < 0.00005) showed a significant higher incidence of hemorrhages than other patients. Resolution of bleeding at home was obtained in 206 (88%) of the 232 episodes; platelet units were transfused at home in 188 (81%) cases. Bleeding was the cause of hospitalisation in four cases. Death occurred in 447 of 469 patients: in 26 of them (6%), it was caused by bleeding complications (11 brain hemorrhage, 2 hematemesis, 3 hemoptysis and 10 melena). In this group of patients, bleeding was a relevant clinical problem However, by implementing a domiciliary palliative care program, home management of hemorrhages proved to be a safe and effective choice.

Management of bleeding and of invasive procedures in patients with platelet disorders and/or thrombocytopenia: Guidelines of the Italian Society for Haemostasis and Thrombosis (SISET)

The optimal management of bleeding or its prophylaxis in patients with disorders of platelet count or function is controversial. The bleeding diathesis of these patients is usually mild to moderate: therefore, transfusion of platelet concentrates may be inappropriate, as potential adverse effects might outweigh its benefit. The availability of several anti-hemorrhagic drugs further compounds this problem, mainly because the efficacy/suitability of the various treatment options in different clinical manifestations is not well defined. In these guidelines, promoted by the Italian Society for Studies on Haemostasis and Thrombosis (Società Italiana per lo Studio dell'Emostasi e della Trombosi [SISET]), we aim at offering the best available evidence to help the physicians involved in the management of patients with disorders of platelet count or function. Literature review and appraisal of available evidence are discussed for different clinical settings and for different available treatments, including platelet concentrates (PC), recombinant activated factor VII, desmopressin, antifibrinolytics, aprotinin and local hemostatic agents.

[Reduction of the platelet transfusion dose and its effects]

BACKGROUND

In Korea, a platelet transfusion dose (TD) of 8 units of platelet concentrates (PC) is usually used. To minimize the shortage of blood products and transfusion-related adverse reactions, the TD has been changed from 8 to 6 units in 2006 in our hospital. Here, we analyzed the dose reduction effect on patients' platelet counts and transfusion frequency.

METHODS

We compared the amount of issued PC, platelet counts before and after transfusion, post-transfusion platelet increments, and transfusion frequencies in patients who were transfused with 8 PC in 2006 and 6 PC in 2008.

RESULTS

Despite an increase in the number of admitted patients by 20% in 2008 with a disease distribution similar to that in 2006, the number of issued PC in 2008 was decreased by 26.6% compared to that in 2006. In 2008, post-transfusion platelet counts, pre-transfusion platelet counts in patients transfused with 320 mL whole blood-derived PC, and platelet increments in patients transfused with 400 mL whole blood-derived PC were significantly decreased. However, the mean transfusion frequency per one month was not significantly different, 4.3 times in 2006 and 4.7 in 2008.

CONCLUSIONS

By implementing a policy of platelet TD restriction, the amount of total issued PC was markedly decreased. Although post-transfusion platelet counts were decreased, the transfusion frequency in a month was not significantly increased. The restriction of platelet TD was helpful for increasing physicians' recognition of blood shortage while achieving similar transfusion effects. We conclude that 6 units of PC would be a better guideline for the platelet TD.

Platelet transfusion during liver transplantation is associated with increased postoperative mortality due to acute lung injury

BACKGROUND

Platelet transfusions have been identified as an independent risk factor for survival after orthotopic liver transplantation (OLT). In this study, we analyzed the specific causes of mortality and graft loss in relation to platelet transfusions during OLT.

METHODS

In a series of 449 consecutive adult patients undergoing a first OLT, the causes of patient death and graft failure were studied in patients who did or did not receive perioperative platelet transfusions.

RESULTS

Patient and graft survival were significantly reduced in patients who received platelet transfusions, compared with those who did not (74% vs 92%, and 69% vs 85%, respectively at 1 yr; P < 0.001). Lower survival rates in patients who received platelets were attributed to a significantly higher rate of early mortality because of acute lung injury (4.4% vs 0.4%; P = 0.004). There were no significant differences in other causes of mortality between the two groups. The main cause of graft loss in patients receiving platelets was patient death with a functioning graft.

CONCLUSIONS

These findings suggest that platelet transfusions are an important risk factor for mortality after OLT. The current study extends previous observations by identifying acute lung injury as the main determinant of increased mortality. The higher rate of graft loss in patients receiving platelets is related to the higher overall mortality rate and does not result from specific adverse effects of transfused platelets on the grafted liver.

Prediction of fatal intracranial hemorrhage in patients with acute myeloid leukemia

BACKGROUND

Intracranial hemorrhage (ICH) is the second leading cause of mortality in patients with acute myeloid leukemia (AML). However, the prognostic factors for ICH in AML patients are still under investigation.

PATIENTS AND METHODS

A total of 841 AML patients admitted to the Department of Internal Medicine from January 1995 to December 2007 were enrolled in this study.

RESULTS

There were 51 patients with ICH, median age of 51 (range 17-86), including 12 patients diagnosed as acute promyelocytic leukemia. Forty-three patients were refractory/relapsed status. ICH was localized in the supratentorium (44 cases), basal ganglion (9), cerebellum (5), and brainstem (4). Twenty-one patients had multiple sites. Thirty-eight patients had intraparenchymal hemorrhage, 16 subarachnoid hemorrhage (SAH), 10 subdural hemorrhage, and one epidural hemorrhage (EDH). Hemorrhage ruptured into the ventricles in 13 patients. Thirty-four patients (67%) died of ICH within 30 days of diagnosis. Multivariate analysis revealed four independent prognostic factors, prolonged prothrombin time international normalized ratio >1.5 (P < 0.001), brainstem hemorrhage (P = 0.001), SAH (P = 0.017), and EDH (P = 0.014). Other clinico-laboratory data had no impact on 30-day survival.

CONCLUSIONS

ICH has high morbidity and mortality in AML. Early detection and aggressive correction coagulopathy may prevent the catastrophic event. Prompt image study for locations and types of ICH can predict outcomes.

The normalization heuristic: an untested hypothesis that may misguide medical decisions

Medical practice is increasingly informed by the evidence from randomized controlled trials. When such evidence is not available, clinical hypotheses based on pathophysiological reasoning and common sense guide clinical decision making. One commonly utilized general clinical hypothesis is the assumption that normalizing abnormal laboratory values and physiological parameters will lead to improved patient outcomes. We refer to the general use of this clinical hypothesis to guide medical therapeutics as the "normalization heuristic". In this paper, we operationally define this heuristic and discuss its limitations as a rule of thumb for clinical decision making. We review historical and contemporaneous examples of normalization practices as empirical evidence for the normalization heuristic and to highlight its frailty as a guide for clinical decision making.

A randomized controlled trial comparing standard- and low-dose strategies for transfusion of platelets (SToP) to patients with thrombocytopenia

A noninferiority study was performed comparing low-dose and standard-dose prophylactic platelet transfusions. A double-blind randomized controlled trial (RCT) was performed in 6 sites in 3 countries. Thrombocytopenic adults requiring prophylactic platelet transfusion were randomly allocated to standard-dose (300-600 × 109 platelets/product) or low-dose (150- < 300 × 109 platelets/product) platelets. The primary outcome (World Health Organization [WHO] bleeding ≥ grade 2) was assessed daily through clinical examination, patient interview, and chart review. A WHO grade was assigned through adjudication. The Data Safety Monitoring Board stopped the study because the difference in the grade 4 bleeding reached the prespecified threshold of 5%. At this time, 129 patients had been randomized and 119 patients were included in the analysis (58 low dose; 61 standard dose). Three patients in the low-dose arm (5.2%) had grade 4 bleeds compared with none in the standard-dose arm. WHO bleeding grade 2 or higher was 49.2% (30/61) in the standard-dose arm and 51.7% (30/58) in the low-dose group (relative risk [RR], 1.052; 95% confidence interval [CI], 0.737-1.502). A higher rate of grade 4 bleeding in patients receiving low-dose prophylactic platelet transfusions resulted in this RCT being stopped. Whether this finding was due to chance or represents a real difference requires further investigation. These clinical studies are registered on http://www.clinicaltrials.gov as NCT00420914.

Clinical management of primary non-acute promyelocytic leukemia acute myeloid leukemia: Practice Guidelines by the Italian Society of Hematology, the Italian Society of Experimental Hematology, and the Italian Group for Bone Marrow Transplantation

As many options are now available to treat patients with de novo acute myeloid leukemia, the Italian Society of Hematology and two affiliated societies (SIES and GITMO) commissioned project to an Expert Panel aimed at developing clinical practice guidelines for acute myeloid leukemia treatment. After systematic comprehensive literature review, the Expert Panel formulated recommendations for the management of primary acute myeloid leukemia (with the exception of acute promyelocytic leukemia) and graded them according to the supporting evidence. When evidence was lacking, consensus-based statements have been added. First-line therapy for all newly diagnosed patients eligible for intensive treatment should include one cycle of induction with standard dose cytarabine and an anthracycline. After achieving complete remission, patients aged less than 60 years should receive consolidation therapy including high-dose cytarabine. Myeloablative allogeneic stem cell transplantation from an HLA-compatible sibling should be performed in first complete remission: 1) in children with intermediate-high risk cytogenetics or who achieved first complete remission after the second course of therapy; 2) in adults less than 40 years with an intermediate-risk; in those aged less than 55 years with either high-risk cytogenetics or who achieved first complete remission after the second course of therapy. Stem cell transplantation from an unrelated donor is recommended to be performed in first complete remission in adults 30 years old or younger, and in children with very high-risk disease lacking a sibling donor. Alternative donor stem cell transplantation is an option in high-risk patients without a matched donor who urgently need transplantation. Patients aged less than 60 years, who either are not candidate for allogeneic stem cell transplantation or lack a donor, are candidates for autologous stem cell transplantation. We describe the results of a systematic literature review and an explicit approach to consensus techniques, which resulted in recommendations for the management of primary non-APL acute myeloid leukemia.

Impact of intensive PBSC mobilization therapy on outcomes following auto-SCT for non-Hodgkin's lymphoma

The best method to mobilize PBSCs in patients with non-Hodgkin's Lymphoma (NHL) is uncertain. We hypothesized that PBSC mobilization using an intensive chemotherapy regimen would improve outcomes after autologous hematopoietic stem cell transplantation (ASCT) in NHL patients at high risk for relapse. Fifty NHL patients were prospectively allocated to intense mobilization with high-dose etoposide plus either high-dose cytarabine or CY if they were 'high risk' for relapse, whereas 30 patients were allocated to nonintense mobilization with CY if they were 'standard risk' (all patients, +/-rituximab). All intensely mobilized patients were hospitalized compared with one-third of nonintensely mobilized patients. The EFS after ASCT was the same between the two groups, but overall survival (OS) was better for intensely mobilized patients (<0.01), including the diffuse large B-cell subgroup (P<0.04). We conclude that the intense mobilization of PBSCs in patients with NHL is more efficient than nonintense mobilization, but with greater toxicity. The equalization of EFS and superiority of OS in patients intensely mobilized to those nonintensely mobilized suggests that a treatment strategy using intensive chemotherapy for mobilization may be improving NHL outcomes after ASCT.

Comparing the efficacy and safety of apheresis and whole blood-derived platelet transfusions: a systematic review

BACKGROUND

A systematic review and meta-analysis was performed to determine if there were differences between apheresis platelet concentrates (APCs) or platelets (PLTs) derived from whole blood (WBD) for the outcomes acute reactions, alloimmunization, refractoriness, corrected count increment (CCI), radiolabeled recovery and survival, time to next transfusion, and bleeding.

STUDY DESIGN AND METHODS

We searched Medline, Embase, the Cochrane Registry of Controlled Trials, PapersFirst, ProceedingsFirst, and AABB and ASH abstracts for randomized controlled trials (RCTs) comparing APCs and WBD PLTs for clinical outcomes. Study selection, data extraction, and methodologic quality assessments were performed in duplicate. Results were pooled using meta-analytic methods.

RESULTS

Ten RCTs met the inclusion criteria. Acute reactions per patient were lower for APCs (relative risk [RR], 0.65; 95% CI, 0.44-0.98); however, when controlling for leukoreduction, there was no significant difference (leukoreduced [LR]-APCs vs. LR-WBDs; odds ratio, 1.78; 95% CI, 0.87-3.62). There was no difference between products when reaction frequencies were assessed per transfusion (RR, 0.65; 95% CI, 0.33-1.28). APCs were associated with significantly higher CCIs than WBD PLTs at both 1 hour (weighted mean difference [WMD], 2.49; 95% CI, 2.21-2.77) and 18 to 24 hours (WMD, 1.64; 95% CI, 0.60-2.67). No conclusions could be made for the outcomes of alloimmunization and refractoriness. No studies addressed outcomes of time to next transfusion or bleeding.

CONCLUSIONS

Owing to the small number of trials and lack of comparability of PLT products for leukoreduction, we were unable to draw definitive conclusions about the clinical benefits of APCs compared with WBD PLTs. Rigorous RCTs using clinically important end points are needed to settle this issue.

Consensus and controversies in platelet transfusion: trigger for indication, and platelet dose

Platelet transfusion is about to commemorate its 50th year since its introduction in therapeutics. It is then surprising to see, that in spite of reaching this respectful age, we have not been able to definitely establish all the aspects related to its clinical use. Some of these facets are platelet transfusion threshold and the platelet dose to administer. Historically, two different transfusion triggers have been used for prophylactic and therapeutic platelet transfusions. For prophylactic platelet transfusion an increasing body of evidences suggests that a transfusion trigger of 10 x 10(9) per liter is appropriate for most clinical settings. In contrast, evidence for supporting a certain therapeutic transfusion trigger is lacking. Nevertheless, there is consensus that the platelet count should not be allowed to fall below 50 x 10(9) per liter in patients with acute bleeding. Another important aspect still pending of clear definition is the issue of the platelet dose to be transfused. It has been addressed by some small studies but a definite answer to this important clinical issue is, at least so far, still pending. The results of two ongoing trials, one sponsored by NIH through the Clinical Trials Network in Transfusion Medicine and Hemostasis and the other promoted by the BEST Collaborative Group are expected to help us to clearly defining the more effective and efficient way to transfuse platelet concentrates.

Platelet count evaluation using three automated haematology analysers compared with the immunoplatelet reference method, and estimation of possible inadequate platelet transfusion

The accuracy of three automated haematology analysers [Sysmex XE-2100 (both optical and impedance mode), Bayer Advia 120, and Beckman Coulter LH-750] was compared with the immunoplatelet reference method for platelet measurement. A total of 165 blood specimens were obtained from patients and platelet counts were determined using the four-automated haematology analyser methods and the immunoplatelet reference method. The coefficients of determination (R(2)) between the automated haematology analyser methods and the immunoplatelet reference method for the overall platelet range were >0.98. A bias study, however, showed some disagreement. The use of a coincidence correction calculation for the immunoplatelet method did not improve the correlation between the immunoplatelet method and the automated haematology analyser methods. To estimate the possibility of inadequate platelet transfusion, the number of prophylactic platelet transfusion indications determined by the automated haematology analyser platelet counts were compared with the number of transfusion indications according to the platelet counts determined by the immunoplatelet method. An additional 48 blood specimens were included in this analysis. All of the automated haematology analysers showed some disagreement in the transfusion indications when compared with the immunoplatelet method, suggesting the possibility of inadequate platelet transfusion.

Clinica use of platelet additive solutions

Randomised clinical trial (RCT) to study the clinical efficacy and safety of new platelet products using platelet additive solutions are scarce. In this paper a number of recent RCT's is discussed. It can be the start of a development where new transfusion products enter a RCT before the product is applied in clinical practice.

New Strategies for the Optimal Use of Platelet Transfusions

Patients with severe thrombocytopenia are presumed to be at increased risk for bleeding, and consequently it has been standard practice for the past four decades to give allogeneic platelet transfusions to severely thrombocytopenic patients as supportive care. Platelet transfusions may be given either prophylactically to reduce the risk of bleeding, in the absence of clinical hemorrhage (prophylactic transfusions), or to control active bleeding when present (therapeutic transfusions). While no one would argue with the need for platelet transfusions in the face of severe bleeding, important questions remain about what constitutes clinically significant bleeding and whether a strategy of prophylactic platelet transfusions is effective in reducing the risk of bleeding in clinically stable patients. It is now uncommon for patients undergoing intensive chemotherapy or bone marrow transplantation to die of hemorrhage, but it is open to debate as to what degree platelet transfusions have been responsible for this change in outcome, given the many other advances in other aspects of supportive care.

If a prophylactic strategy is followed, the optimal transfusion trigger or quantity of platelets to be transfused prophylactically per transfusion episode needs to be addressed in adequately powered clinical trials, but these remain highly controversial issues. This is because, until recently, there have been few high-quality, prospective, randomized clinical trial (RCT) data for evaluating the relative effects of different platelet transfusion regimens or platelet doses on clinical outcomes. Moreover, most of these RCTs have not used bleeding as the primary outcome measure. Two such studies on platelet dose have now been undertaken, the PLADO (Prophylactic PLAtelet DOse) and the SToP (Strategies for the Transfusion of Platelets) trials. Data from these RCTs are not contained in this overview, as these data have not yet been completely analyzed or submitted for peer review publication.

In addition to the above, several recent observational studies have raised the possibility that there is not a clear association between the occurrence of a major clinical bleeding episode and the platelet count in thrombocytopenic patients. Such findings have led to the questioning of the efficacy of prophylactic platelet transfusions in all clinically stable patients, and whether a policy of therapeutic transfusions used only when patients have clinical bleeding might be as effective and safe for selected patients. At least two RCTs evaluating the relative value of prophylactic versus therapeutic platelet transfusions have been initiated in thrombocytopenic patients with hematological malignancies. One such study, known as the TOPPS (Trial of Prophylactic Platelets Study) study, is currently underway in the U.K.

Profound thrombocytopenia and survival of hematopoietic stem cell transplant patients without clinically significant bleeding, using prophylactic platelet transfusion triggers of 10 x 10(9) or 20 x 10(9) per L

BACKGROUND

A trigger of 10 x 10(9) per L for prophylactic platelet (PLT) transfusions is generally recommended for stable thrombocytopenic patients who receive chemotherapy, based on studies showing similar incidence, severity, and fatality of bleeding compared with the 20 x 10(9) per L trigger. The outcome of thrombocytopenic nonbleeding patients has not been well described. This retrospective analysis evaluates thrombocytopenia and survival of 381 hematopoietic stem cell transplant (HSCT) patients without clinically significant bleeding, with 10 x 10(9) and 20 x 10(9) per L prophylactic triggers.

STUDY DESIGN AND METHODS

A total of 170 patients who received prophylactic PLT transfusions at 20 x 10(9) per L (1997-1998, SP1) and 211 patients who had prophylaxis at 10 x 10(9) per L (1999-2001, SP2) were identified as nonbleeding patients. PLT counts and clinical complications were assessed within 100 days from HSCT.

RESULTS

PLT counts less than or equal to 10 x 10(9) per L were found in 69.2 percent of patients in SP2 and 38.3 percent in SP1 (p < 0.001). Profound thrombocytopenia (4+ PLT counts <or=10 x 10(9)/L) was found in 19.0 percent of patients in SP2 and 7.0 percent in SP1 (p = 0.001). Patients with profound thrombocytopenia had significantly increased early mortality (odds ratio [OR], 3.18; 95% confidence interval [CI], 1.25-8.07) and significantly reduced overall survival (hazard ratio [HR], 1.95; 95% CI, 1.28-2.97) compared to patients with 0 to 3 PLT counts less than or equal to 10 x 10(9) per L. The association of profound thrombocytopenia with early mortality was more notable in SP2.

CONCLUSION

The 10 x 10(9) per L transfusion trigger is associated with significantly greater exposure to low PLT counts. Nonbleeding patients with profound thrombocytopenia were at significantly greater risk of dying compared with nonthrombocytopenic patients. These results suggest that safety of the 10 x 10(9) per L trigger should be more thoroughly evaluated.

Disseminated intravascular coagulation

OBJECTIVE

To review the current knowledge on the clinical manifestation, pathogenesis, diagnosis, and management of disseminated intravascular coagulation (DIC).

DATA SOURCE

Selected articles from the MEDLINE database.

DATA SYNTHESIS

DIC may complicate a variety of disorders and can cause significant morbidity (in particular related to organ dysfunction and bleeding) and may contribute to mortality. The pathogenesis of DIC is based on tissue factor-mediated initiation of systemic coagulation activation that is insufficiently contained by physiologic anticoagulant pathways and amplified by impaired endogenous fibrinolysis. The diagnosis of DIC can be made using routinely available laboratory tests and scoring algorithms. Supportive treatment of DIC may be aimed at replacement of platelets and coagulation factors, anticoagulant treatment, and restoration of anticoagulant pathways.

CONCLUSIONS

Insight into the pathogenesis of DIC has resulted in better strategies for clinical management, including straightforward diagnostic criteria and potentially beneficial supportive treatment options.

A multicenter pilot-randomized controlled trial of the feasibility of an augmented red blood cell transfusion strategy for patients treated with induction chemotherapy for acute leukemia or stem cell transplantation

BACKGROUND

Anemia may be an important factor contributing to an increased risk of bleeding, particularly in patients with thrombocytopenia.

STUDY DESIGN AND METHODS

A multicenter, single-blinded pilot randomized controlled trial (RCT) was performed to evaluate the feasibility of conducting a larger RCT to determine the effect of the hemoglobin (Hb) concentration on bleeding risk. Patients with acute leukemia receiving induction chemotherapy or those undergoing stem cell transplantation were assigned to one of two treatment groups: standard transfusion strategy (transfusion of 2 units of red blood cells [RBCs] when their Hb level was less than 80 g/L) or an augmented transfusion strategy (transfusion of 2 units of RBCs when their Hb level was less than 120 g/L).

RESULTS

Sixty patients were enrolled: 29 in the control group and 31 in the experimental group. The proportions of patients experiencing clinically significant bleeding and the time to first bleed were not significantly different between the control and experimental groups. The experimental group received more RBC transfusions (transfusions/patient-day) than the control group (0.233 vs. 0.151; relative risk, 1.56; 95% confidence interval, 1.16-2.10; p = 0.003). The proportion of patient-days with platelet (PLT) transfusions was not different between the experimental and control groups. The mean number of donor exposures (PLT and RBC transfusions) was not different between experimental and control groups. Bleeding symptoms were systematically documented.

CONCLUSION

This pilot study thus indicated that it would be feasible to enroll the required number of patients to enable the performance of a large RCT to investigate the effect of Hb on bleeding risk in thrombocytopenic patients.

Variable levels of carry over on platelet counts < or = 20 x 10(9)/l with the Bayer Advia 120

Accurate platelet counts are essential for the safe management of severe thrombocytopenia (platelet counts < or = 20 x 10(9)/l). The effect of carry over on platelet counting in severe thrombocytopenia was investigated by performing counts before and after saline rinses on three Bayer Advia 120 automated blood counters. Counts were performed in both primary and manual closed tube system modes on two instruments and in manual open tube mode on a third. A total of 194 samples with platelet counts < or = 20 x 10(9)/l were studied. First counts were significantly higher in all groups. The magnitude of the difference varied both by analyser and counting mode. Carry over was minimal with one analyser in primary mode and second counts were on average only 5.5% lower; on a second analyser in manual closed tube system mode second counts were on average 37.7% lower. A first count of > or = 10 x 10(9)/l fell to <10 x 10(9)/l on the second count in 35 of 145 samples (24.1%). In five such samples, all tested on one analyser, the second count was <50% of the value of the first count. Two of 49 (4.1%) first counts of <10 x 10(9)/l increased to > or = 10 x 10(9)/l on repeat. These results show a variable and often potentially clinically important carry-over effect on severely thrombocytopenic samples using the Advia 120.

Platelet transfusions

Ever since platelet transfusions were shown to reduce mortality from haemorrhage in patients with acute leukaemia in the 1950s, the use of this therapy has steadily grown to become an essential part of the treatment of cancer, haematological malignancies, marrow failure, and haematopoietic stem cell transplantation. Today, more than 1.5 million platelet products are transfused in the USA each year, 2.9 million products in Europe. However, platelet transfusion can transmit infections and trigger serious immune reactions and they can be rendered ineffective by alloimmunisation. There are several types of platelet components and all can be modified to reduce the chances of many of the complications of platelet transfusion. Transfusion practices, including indications for transfusion, dose of platelets transfused, and methods of treating alloimmunised recipients vary between countries, and even within countries. We review commonly used platelet components, product modifications, transfusion practices, and adverse consequences of platelet transfusions.

Platelet Transfusion Therapy

This article provides guidelines for the appropriate use of platelet transfusions to reduce unnecessary transfusions, thereby avoiding transfusion-related risks to the patients and the costs of platelet therapy. Platelet products available for transfusion are whole blood derived platelet concentrates and apheresis platelets. Leukoreduced platelets can be used to reduce platelet alloimmunization, cytomegalovirus transmission, and febrile transfusion reactions, while gamma irradiation prevents transfusion-associated graftversus-host disease. Other topics discussed are the expected response to transfused platelets and reasons for poor responses related to alloimmunization, underlying disease state, clinical conditions, and drugs. Appropriate transfusion guidelines based on pretransfusion platelet count, platelet dose, and whether the transfusion is prophylactic or therapeutic are outlined. Identification, prevention, and management of adverse consequences of platelet transfusions and platelet refractoriness are discussed.

Planning for pandemic influenza: effect of a pandemic on the supply and demand for blood products in the United States

BACKGROUND

Influenza causes episodic pandemics when viral antigens shift in ways that elude herd immunity. Avian influenza A H5N1, currently epizootic in bird populations in Asia and Europe, appears to have pandemic potential.

STUDY DESIGN AND METHODS

The virology of influenza, the history of the 1918 pandemic, and the structure of the health care and the blood transfusion systems are briefly reviewed. Morbidity and mortality experience from the 1918 pandemic are projected onto the current health care structure to predict points of failure that are likely in a modern pandemic.

RESULTS

Blood donor centers are likely to experience loss of donors, workers, and reliable transport of specimens to national testing laboratories and degradation of response times from national testing labs. Transfusion services are likely to experience critical losses of workers and of reagent red cells (RBCs) that will make their automated procedures unworkable. Loss of medical directors, supervisors, and lead technicians may make alternative procedures unworkable as well.

CONCLUSIONS

Lower blood collection capacity and transfusion service support capability will reduce the availability of RBCs and especially of platelets. Plans for rationing medical care need to take the vulnerability of the blood transfusion system into account.

Facteurs influençant le rendement transfusionnel plaquettaire « une interdépendance entre le patient et le produit »

A great variety of patient- and product-related factors influence the outcome of platelet transfusions. The patient-related factors are numerous, either physical factors as weight and height, or related to pathological being as splenomegaly, fever, infection, disseminated intravascular coagulation, previous HLA allo-immunization, or related to the treatment, as amphotericin. Major platelet factors that are associated with impaired responses are giving a decreased dose of platelets, ABO incompatible products, and platelets stored for more than 48 hours. When trying to prevent or to treat refractoriness and to finely tune platelet transfusions, all these factors have to be taken into account, and a good coordination between the blood bank and the clinician team is essential.

Acute bleeding complications in patients after hematopoietic stem cell transplantation with prophylactic platelet transfusion triggers of 10�נ109and 20�נ109per L

BACKGROUND

Prophylactic platelet (PLT) transfusions are given as a standard care in patients with hematologic malignancies undergoing hematopoietic stem cell transplantation (HSCT). This retrospective analysis evaluates utilization of blood transfusions, risk of bleeding, and survival in 480 HSCT patients at 10 x 10(9) and 20 x 10(9) per L prophylactic trigger levels.

STUDY DESIGN AND METHODS

A total of 224 patients received prophylactic PLT transfusions at 20 x 10(9) per L threshold (1997-1998, SP1); 256 patients had prophylaxis at 10 x 10(9) per L (1999-2001, SP2). Bleeding scores were assigned daily.

RESULTS

A slight reduction in PLT transfusions per patient in SP2 compared with SP1 was not statistically significant (odds ratio, 0.82; 95% confidence interval, 0.51-1.33; p = 0.416), yet a significantly higher proportion of patients in SP2 had PLT counts less than or equal to 10 x 10(9) per L compared to SP1 (p < 0.001). In patients who bled, however, there was no excess exposure to low PLT counts before bleeding started. A substantial number of patients who bled received PLT transfusions above the goal before bleeding started (82.9% in SP2, 41.5% in SP1) because of medical complications that associated with increased risk of bleeding. Bleeding incidence was similar in both study periods (21.9% in SP1, 16.4% in SP2; p = 0.526). Bleeding was significantly associated with reduced survival in both study periods.

CONCLUSIONS

Patients who bled were usually placed on a higher threshold before the onset of their major bleeding event and were not exposed to additional risk of bleeding from thrombocytopenia. Similarity in bleeding incidence between study periods appears to associate with adjustments to high-risk conditions and may not reflect consequences of the lower transfusion threshold.

Continuing developments with the automated platelet count1

The four main procedures for platelet counting are: manual phase contrast microscopy, impedance, optical light scatter/fluorescence and flow cytometry. Early methods to enumerate platelets were inaccurate and irreproducible. The manual count is still recognized as the gold standard or reference method, and until very recently the calibration of platelet counts by the manufacturers of automated cell counters and quality control material was performed by this method. However, it is time-consuming and results in high levels of imprecision. The introduction of automated full blood counters using impedance technology resulted in a dramatic improvement in precision. However, impedance counts still have limitations as cell size analysis cannot discriminate platelets from other similar-sized particles. More recently, light scatter or fluorescence methods have been introduced for automated platelet counting, but there are still occasional cases where an accurate platelet count remains a challenge. Thus, there has been interest in the development of an improved reference procedure to enable optimization of automated platelet counting. This method utilizes monoclonal antibodies to platelet cell surface antigens conjugated to a suitable fluorophore. This permits the possible implementation of a new reference method to calibrate cell counters, assign values to calibrators, and to obtain a direct platelet count on a variety of pathological samples. In future, analysers may introduce additional platelet parameters; a reliable method to quantify immature or reticulated platelets would be useful.

Evaluation of platelet transfusion triggers in a tertiary-care hospital

BACKGROUND

Our 1100-bed referral hospital uses approximately 12,000 units of random-donor platelets (PLTs) and 1,900 units of single-donor apheresis PLTs per year with a mean of 23 percent outdating. An analysis of patterns of utilization has been undertaken to evaluate practice.

STUDY DESIGN AND METHODS

Over a 9-month period, data were collected on a total of 1682 transfusion episodes in 464 patients. When the pretransfusion count was greater than 10 x 10(9) per L an attempt was made to identify the specific indications for PLT transfusions such as bleeding.

RESULTS

The majority (78%) of PLTs were transfused when the counts were above 10 x 10(9) per L. The mean pretransfusion counts for different services were: bone marrow transplant (BMT) 17.4 x 10(9) per L, hematology-oncology 14.6 x 10(9) per L, the Heart Institute 3 x 10(9) per L, and other services 36 x 10(9) per L. The percentage of transfusions given to patients with a count greater than 10 x 10(9) per L varied by service with 79 percent in BMT, 60 percent in hematology and oncology, 98 percent at the Heart Institute, and 81 percent in other services. Routine monitoring of counts shows a mean increment of 10.2 x 10(9) per L per transfusion. One hour posttransfusion counts, 24-hour posttransfustion counts, and documentation of clinical justification for transfusions was often not available.

CONCLUSIONS

The data show that most patients who receive PLTs have pretransfusion counts of more than 10 x 10(9) per L and more than one-third have pretransfusion counts of greater than 20 x 10(9) per L. The medical literature supports prophylactic PLT transfusion based solely on the count when the PLT number is 10 x 10(9) per L or less. Above this level additional justification is needed although there are different points of view concerning the appropriate triggers. Our data suggest that there is a need for clear hospital transfusion guidelines and ongoing monitoring of PLT use.

Platelet utilization and the transfusion trigger: a prospective analysis

BACKGROUND

Prophylactic platelet (PLT) transfusion practices have become more conservative as studies support a threshold for transfusions at 10 x 10(9) per L. This change in practice may reduce our use of PLT transfusions.

STUDY DESIGN AND METHODS

Data were prospectively collected to assess the impact at one academic hospital when the transition from a 20 x 10(9) to a 10 x 10(9) per L threshold prophylactic transfusion was made.

RESULTS

A total of 503 patients received 7401 PLT transfusions. Seventy-four percent of the transfusions were prophylactic. During the first phase of the study, only 53 percent of transfusions were given at a pretransfusion PLT count of less than 20 x 10(9) per L and 20 percent less than 10 x 10(9) per L. In the second phase of the study when the transfusion trigger was 10 x 10(9) per L, 28 percent of transfusions were given at this level.

CONCLUSION

Many prophylactic PLT transfusions were given at PLT counts higher than the recommended trigger. Although the new transfusion guidelines altered transfusion practice, only a minor change in overall PLT usage was observed. Other changes in transfusion practices, such as dose per transfusion or sampling interval, will be required before significant reduction in the costs and hazards of prophylactic PLT transfusions can be realized.