Safety of stringent prophylactic platelet transfusion policy for patients with acute leukaemia

Hyperthermia inhibits platelet hemostatic functions and selectively regulates the release of alpha-granule proteins

BACKGROUND

Hyperthermia is one of the main disturbances of homeostasis occurring during sepsis or hypermetabolic states such as cancer. Platelets are important mediators of the inflammation that accompanies these processes, but very little is known about the changes in platelet function that occur at different temperatures.

OBJECTIVES

To explore the effect of higher temperatures on platelet physiology.

METHODS

Platelet responses including adhesion, spreading (fluorescence microscopy), α(IIb)β(3) activation (flow cytometry), aggregation (turbidimetry), ATP release (luminescence), thromboxane A(2) generation, alpha-granule protein secretion (ELISA) and protein phosphorylation from different signaling pathways (immunoblotting) were studied.

RESULTS

Preincubation of platelets at temperatures higher than 37 °C (38.5-42 °C) inhibited thrombin-induced hemostasis, including platelet adhesion, aggregation, ATP release and thromboxane A(2) generation. The expression of P-selectin and CD63, as well as vascular endothelial growth factor (VEGF) release, was completely inhibited by hyperthermia, whereas von Willebrand factor (VWF) and endostatin levels remained substantially increased at high temperatures. This suggested that release of proteins from platelet granules is modulated not only by classical platelet agonists but also by microenvironmental factors. The observed gradation of response involved not only antiangiogenesis regulators, but also other cargo proteins. Some signaling pathways were more stable than others. While ERK1/2 and AKT phosphorylation were resistant to changes in temperature, Src, Syk, p38 phosphorylation and IkappaB degradation were decreased in a temperature-dependent fashion.

CONCLUSIONS

Higher temperatures, such as those observed with fever or tissue invasion, inhibit the hemostatic functions of platelets and selectively regulate the release of alpha-granule proteins.

Clinical outcome of leukemia patients with intracranial hemorrhage

Object

Intracranial hemorrhage (ICH) is a frequent complication found in leukemia patients with thrombocytopenia. At the University of Texas MD Anderson Cancer Center, when a leukemia patient is found to have ICH, a platelet transfusion is generally recommended until 50,000/μl is reached. The authors examine the feasibility and outcome of their intervention strategy in this study.

Methods

Records were reviewed from 76 consecutive leukemia patients with newly diagnosed ICH at the University of Texas MD Anderson Cancer Center from January 1, 2007, to December 31, 2009. Variables of interest included age, platelet count at presentation, leukemia subtype, history of trauma, Glasgow Coma Scale score at presentation, whether the 50,000/μl goal was reached after transfusion, and whether the patient was a transfusion responder (platelet count increase > 2000/μl/unit transfused). Outcome parameters were mortality rates at 72 hours and 30 days and imaging-documented hemorrhage progression.

Results

Thrombocytopenia was prevalent at the time of presentation (68 of 76 patients had platelet levels < 50,000/μl at presentation). Despite an aggressive transfusion protocol, only 24 patients reached the 50,000/μl target after an average of 16 units of transfusion. Death due to ICH occurred in 15 patients within the first 72 hours (mortality rate 19.7%). Death correlated with the presenting Glasgow Coma Scale score (p = 0.0075) but not with other transfusion-related parameters. A significant mortality rate was again observed after 30 days (32.7%). The 30-day mortality rate, however, was largely attributable to non-ICH related causes and correlated with patient age (p = 0.032) and whether the patient was a transfusion responder (p = 0.022). Reaching and maintaining a platelet count > 50,000/μl did not positively correlate with the 30-day mortality rate (p = 0.392 and 0.475, respectively).

Conclusions

Platelet transfusion in the setting of ICH in leukemia patients is undoubtedly necessary, but whether the transfusion threshold should be 50,000/μl remains unclear. Factors other than thrombocytopenia likely contribute to the overall poor prognosis.

Optimal preprocedural platelet transfusion threshold for central venous catheter insertions in patients with thrombocytopenia

BACKGROUND

Patients with severe thrombocytopenia are at risk for bleeding during insertion of central venous catheters (CVCs). Although most guidelines recommend preprocedural platelet (PLT) transfusions at a threshold of less than 50 × 10(9) /L, there is only weak evidence supporting such recommendations.

STUDY DESIGN AND METHODS

The current study aimed to establish a safe PLT transfusion trigger in patients with CVC placements. We performed a retrospective single-center analysis of 604 CVC insertions in 193 patients with acute leukemia receiving intensive chemotherapy or stem cell transplantation.

RESULTS

A total of 48% of the patients had a bleeding risk during CVC insertions, mostly due to thrombocytopenia. The bleeding incidence was 32% with 96% Grade 1 and 4% Grade 2 bleedings requiring prolonged local compression. There were no Grade 3 to 4 bleedings. Hemoglobin levels were similar before and 24 and 48 hours after the CVC insertion in the bleeding and nonbleeding group and there was no difference in the red blood cell (p = 0.72) and PLT transfusion requirements (p = 0.057) after CVC insertion. In multivariate analysis, only patients with PLT counts of less than 20 × 10(9) /L were at higher risk for bleeding before (p = 0.015) and after preprocedural PLT transfusions (p =0.006) compared to patients with PLT counts of 100 × 10(9) /L or more.

CONCLUSION

CVC placements can safely be performed in patients with PLT counts of 20 × 10(9) /L or more without preprocedural PLT transfusions.

Current practice and future directions for optimization of platelet transfusions in patients with severe therapy-induced cytopenia

Platelet transfusions are mainly used for patients with thrombocytopenia due to bone marrow failure, especially cancer patients developing severe chemotherapy-induced thrombocytopenia (e.g. patients with acute leukemia or other hematologic malignancies). A prophylactic transfusion strategy is now generally accepted in developed countries. Some clinical data, however, support the use of a therapeutic transfusion strategy at least for certain subsets of these patients. Several methodological approaches can then be used to evaluate the outcome of platelet transfusions, including peripheral blood platelet increments and bleeding assessments. Several factors will influence the efficiency of platelet transfusions; fever and ongoing hemorrhage are among the most important patient-dependent factors, but the number and quality of the transfused platelets are also important. The quality of transfused platelets can be evaluated by analyzing platelet activation, metabolism or senescence/apoptosis. Only evaluation of metabolism is included in international guidelines, but high-throughput methods for evaluation of activation and senescence/apoptosis are available and should be incorporated into routine clinical practice if future studies demonstrate that they reflect clinically relevant platelet characteristics. Finally, platelet transfusions have additional biological effects that may cause immunomodulation or altered angioregulation; at present it is not known whether these effects will influence the long-time prognosis of cancer patients. Thus, several questions with regard to the optimal use of platelet transfusions in cancer patients still need to be answered.

Thrombocytopenia and platelet transfusions in patients with cancer

Platelet transfusions are a critical component of the supportive care for patients receiving intensive therapy for hematologic malignancies. The platelet count "triggering" prophylactic transfusion has decreased over the years, and studies comparing a prophylactic versus a therapeutic transfusion approach are in progress. The evidence supporting the need for platelet transfusions prior to different invasive procedures is reviewed. Lastly, studies evaluating the use of thrombopoietic stimulating agents to reduce hemorrhage and decrease the need for platelet transfusions are discussed. To date, there is no evidence that this approach is of clinical utility.

Thrombocytopenia and the risk of bleeding during treatment with peginterferon alfa and ribavirin for chronic hepatitis C

BACKGROUND & AIMS

Chronic HCV patients with baseline thrombocytopenia are often excluded from treatment with peginterferon alfa and ribavirin or undergo many dose reductions of peginterferon alfa. The aim of this study was to investigate the correlation between thrombocytopenia and the occurrence of bleedings during antiviral treatment for HCV infection.

METHODS

In this single center cohort study 2876 visits of 321 patients treated with peginterferon alfa and ribavirin were evaluated for thrombocytopenia, bleedings and dose reductions during HCV treatment.

RESULTS

Mean platelet count at baseline was 207,000/microl for non-cirrhotic patients (n=253) and 132,000/microl for cirrhotic patients (n=68). Mean platelet drop was 42% from 191,000 to 113,100/microl (range 8000-284,000/microl). Severe thrombocytopenia (platelet counts <50,000/microl) was observed in 30 patients (9.3%) at 166 visits and 9 patients developed platelet counts <25,000/microl at 15 visits. Forty-eight bleedings were observed in 27 patients (8.4%). Only one bleeding, due to gastrointestinal angiodysplasia, was defined as severe. However, this patient did not have severe thrombocytopenia at the time of bleeding. During visits, patients reported more minor bleedings when platelet counts were <50,000/microl compared to visits with platelet counts 50,000/microl (11.4% vs. 1.1%, p<0.001). In the multivariate analysis, platelet count of <50,000/microl was a significant predictor of bleeding (p<0.001).

CONCLUSIONS

Severe bleedings did not occur in patients with platelet counts below 50,000/microl; based on these findings, treatment with peginterferon alfa and ribavirin appears to be safe in patients with platelet counts below 50,000/microl although platelet counts below 25,000/microl were rare.

Incidence and etiology of overt gastrointestinal bleeding in adult patients with aplastic anemia

Patients with thrombocytopenia caused by various neoplastic and primary bone marrow diseases are susceptible to major hemorrhage. There are few reports addressing the incidence and outcome of gastrointestinal (GI) bleeding in patients with aplastic anemia characterized by long-standing thrombocytopenia. We sought to retrospectively determine the incidence, etiology, clinical outcomes, and risk factors associated with overt GI bleeding in patients with aplastic anemia. We analyzed the medical records of 508 patients with aplastic anemia after excluding patients below 15 years of age or those who underwent stem cell transplantation between January 1, 2002, and December 31, 2007. A total of 32 patients developed overt GI bleeding during this period. We evaluated the site, etiology, outcomes, and major risk factors in these patients who developed GI bleeding episodes. The incidence of GI bleeding was 6.3% (32 of 508 patients) in adult patients with aplastic anemia. The incidence increased to 12.6% (28 of 222 patients) in patients with severe disease. One patient died from massive GI bleeding. Bleeding sites included the esophagus (two patients, 6.3%), stomach (five, 16.3%), duodenum (two, 6.3%), small intestine (five, 15.6%), large intestine (seven, 21.6%), and unknown site (11, 34.4%). Lower GI bleeds mainly caused by neutropenic enterocolitis (NEC) and solitary ulcer developed more frequently than upper GI bleeds. The major risk factors for GI bleeding included old age (P = 0.004, odds ratio (OR) = 1.039), severe aplastic anemia (P < 0.001, OR = 11.934), non-response to therapy (P = 0.001, OR = 5.652), and major bleeding history in another organ (P < 0.001, OR = 6.677). Overt GI bleeding in patients with aplastic anemia more frequently develops in the lower tract than in the upper tract. The risk of GI bleeding is higher in patients with the following risk factors: older age, severe disease, poor response to treatment, and major bleeding history in another organ.

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.

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.

[Transfusion in haematology]

In the field of oncohematology, the rationale for the use of blood transfusion relies both on the proliferative advantage of the transformed clone over the others and on hematologic toxicity of chemotherapy. In France, transfusion thresholds are established by a consensus conference organized by the Agence française de sécurité sanitaire des produits de santé (Afssaps), the French health products safety agency: 80g/l for PRC and 10G/l for platelets concentrates in patients without additional hemorragic risk factors. For FFP especially in TTP, thresholds are more patient-related. Transfusion for sickle cell patients remains a scientific challenge.

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.

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.

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.

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.

Management of thrombocytopenia in bone marrow failure: a review

The clinical course of many neoplastic and primary bone marrow diseases will result in cytopenias secondary to bone marrow failure or infiltration. Acute and chronic leukemias, the myelodysplastic syndromes (MDS), aplastic anemia, breast and prostate cancer, as well as other hematologic and solid tumors, all may lead to chronic, severe cytopenias. Management of anemia and neutropenia are well described in the medical literature. Less well detailed are management approaches for patients with chronic thrombocytopenia, with or without active bleeding. Severe thrombocytopenia presents many difficult management choices for caregivers, patients and their families, especially near the end of life. The use of platelet transfusions in this patient population presents complex issues; platelets are logistically more difficult to transfuse than red cells and carry risks including acute febrile episodes, alloimmunization, and infection. In this review, we discuss the association of chronic thrombocytopenia to serious bleeding and the role of various prophylactic and therapeutic interventions available to palliative care and hospice providers. Specifically, this review examines the following issues: What is the morbidity and mortality from chronic thrombocytopenia in the setting of cancer or other bone marrow failure states? Is there a role for prophylactic platelet transfusions in the palliative care setting, and if so, with what frequency of monitoring, and at what transfusion threshold? What is the impact of alloimmunization and how can it be minimized? What treatments are available besides, or in addition to, platelet transfusions for acute bleeding episodes?

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.

Guidelines for the transfusion of platelets

Recommendations aiming at standardising and rationalising clinical indications for the transfusion of platelets in Belgium were drawn up by a working group of the Superior Health Council. To this end the Superior Health Council organised an expert meeting devoted to "Guidelines for the transfusion of platelets" in collaboration with the Belgian Hematological Society. The experts discussed the indications for platelet transfusions, the ideal platelet concentrate and the optimal platelet transfusion therapy. The recommendations prepared by the experts were validated by the working group with the purpose of harmonising platelet transfusion in Belgian hospitals.

A study of the agreement between patient self-assessment and study personnel assessment of bleeding symptoms

BACKGROUND

Clinical trials investigating new platelet transfusion therapies frequently require the assessment of bleeding for the study outcome. These assessments are commonly performed by study personnel and can be time-consuming. The purpose of this study was to assess whether patients were able to reliably assess their bleeding status on a daily basis.

STUDY DESIGN AND METHODS

Patients admitted to hospital to receive chemotherapy for acute leukemia or to undergo allogeneic peripheral blood progenitor cell transplant were included. Patients were given an introduction to a form for documenting the occurrence of 16 bleeding symptoms. Patients completed this form and were examined daily by a study assessor. A weekly health record review was also performed by a study assessor. The agreement between raters was determined by calculating the raw agreement, chance-corrected agreement, and chance-independent agreement.

RESULTS

Thirty-five patients completed 458 assessment forms that were paired with 559 forms completed by a study assessor with 450 matched forms available for analysis (mean, 12.86 per patient). Agreement for most individual bleeding symptoms was high. Thirteen items had agreement greater than 90 percent and all items had agreement greater than 77 percent. The lowest agreement was seen for skin symptoms: petechiae (89.2%), purpura (80.9%), and ecchymosis (77.6%). The negative predictive value of patient self-assessment was high (range, 71.1%-100%) whereas the positive predictive value was lower (range, 0%-86.5%).

CONCLUSION

The reliability was very good between patients and study assessors with the patients reporting excellent negative predictive value and variable positive predictive value.

Risk score model for fatal intracranial hemorrhage in acute leukemia

To build a risk score (RS) model of fatal intracranial hemorrhage (FICH) in patients with acute leukemia, we retrospectively assessed risk factors in 792 patients newly diagnosed with acute leukemia, 41 of whom had analyzable FICH. We found that female gender (relative risk (RR) = 5.234, P<0.001), acute promyelocytic leukemia (RR = 4.057, P = 0.003), leukocytosis (RR = 3.301, P = 0.004), thrombocytopenia (RR = 3.283, P = 0.005) and prolonged prothrombin time (RR = 3.291, P = 0.016) were significantly associated with occurrence of FICH in multivariate analysis. To calculate RS for FICH, one point was assigned for each risk factor, making the RS between 0 and 5. The RS model segregated patients into three prognostic groups: a low-risk group (LRG) for RS of 0 or 1; an intermediate-risk group (IRG) for RS of 2 or 3; and a high-risk group (HRG) for RS of 4 or 5. Expectation of FICH was well correlated with risk groups (all P-values < 0.001). Overall survival was significantly shorter in the HRG compared with the LRG. The RS model we constructed to predict the occurrence of FICH will be verified through prospective studies.

A descriptive analysis of international transfusion practice and bleeding outcomes in patients with acute leukemia

BACKGROUND

Recently, bleeding has been used in platelet (PLT) trials rather than surrogate outcomes. The purpose of this study was to provide a descriptive summary of data from PLT studies conducted in four countries and exploratory analyses to determine the relationship between bleeding and PLT count.

STUDY DESIGN AND METHODS

A descriptive analysis was performed on original data from the Italian trigger study, the US TRAP study, the Canadian febrile reaction study, and a clinical chart review from one hospital site in the United Kingdom. The relationship between bleeding and PLT count was explored with the Italian data.

RESULTS

A total of 897 patients with acute leukemia received 10,506 PLT transfusions. Grade 3 or Grade 4 WHO bleeding frequency was 28.1 percent (252/897) but varied by country: Italy, 10.8 percent (27/250); United States, 36.4 percent (217/598); Canada, 18.9 percent (7/37); and the United Kingdom, 8.3 percent (1/12). Grade 1 or Grade 2 bleeding was reported only in the Italian study (46.4%[116/250] and 11.6%[29/250], respectively). The relative rates of WHO Grade 2, 3, or 4 bleeding for PLT counts in the ranges of 0 to 4, 5 to 9, 10 to 14, and 15 to 19 (x10(9)/L) were 8.8, 1.9, 1.8, and 1.2, respectively, compared to those counts within the range of 20 to 29 (x10(9)/L).

CONCLUSION

The study provides descriptive data on PLT use and frequency of bleeding. When PLT counts were 0x10(9) to 4x10(9) per L there was an eightfold increase in bleeding and a twofold risk increase when counts were 5x10(9) to 14x10(9) per L compared to the 20x10(9) to 29x10(9) per L reference range. The increased rate of bleeding at low counts occurred despite PLT therapy.

Platelets photochemically treated with amotosalen HCl and ultraviolet A light correct prolonged bleeding times in patients with thrombocytopenia

BACKGROUND

Photochemical treatment (PCT) with amotosalen HCl with ultraviolet A illumination inactivates pathogens and white blood cells in platelet (PLT) concentrates.

STUDY DESIGN AND METHODS

In a Phase II crossover study, 32 patients with thrombocytopenia received one transfusion of PCT and/or one transfusion of untreated (reference) apheresis PLTs. Hemostatic efficacy was assessed with the cutaneous template bleeding time and clinical observations.

RESULTS

Paired bleeding time data for PCT and reference transfusions were available for 10 patients. Mean pretransfusion bleeding times were 29.2 +/- 1.6 minutes in the PCT group and 28.7 +/- 2.5 minutes in the reference group. After transfusion of a dose of PLTs of at least 6.0 x 10(11), mean 1-hour posttransfusion template bleeding times corrected to 19.3 +/- 9.5 minutes in the PCT group and 14.3 +/- 6.5 minutes in the reference group (p = 0.25). In 29 patients receiving paired PCT and reference transfusions, mean 1-hour posttransfusion PLT count increments were 41.9 x 10(9) +/- 20.8 x 10(9) and 52.3 x 10(9) +/- 18.3 x 10(9) per L for PCT and reference, respectively (p = 0.007), and mean 1-hour posttransfusion PLT corrected count increments (CCIs) were 10.4 x 10(3) +/- 4.9 x 10(3) and 13.6 x 10(3) +/- 4.3 x 10(3) for PCT and reference, respectively (p < 0.001). The time to next PLT transfusion was 2.9 +/- 1.2 days after PCT transfusions versus 3.4 +/- 1.3 days after reference transfusions (p = 0.18). Clinical hemostasis was not significantly different after PCT and reference transfusions.

CONCLUSION

PCT PLTs provided correction of prolonged bleeding times and transfusion intervals not significantly different than reference PLTs despite significantly lower PLT count increments and CCIs.

Immature platelet fraction measurement: a future guide to platelet transfusion requirement after haematopoietic stem cell transplantation

summary. The decision to prophylactically transfuse platelets is dependent on the platelet count, careful regular clinical assessment and agreed local protocol. The ability to predict when platelet recovery will occur should allow a more reasoned approach to platelet transfusion. An increase in reticulated platelets demonstrates impending platelet recovery. A new rapid automated method to assess reticulated platelets, the immature platelet fraction (IPF), is described, and its clinical utility assessed. The IPF is identified by flow cytometry with the use of a nucleic acid specific dye in the reticulocyte channel on the Sysmex XE-2100. Fifty healthy adult volunteers were used to establish the normal range. Patients where platelet marrow production or destruction might be abnormal were studied, and some patients followed serially during treatment. Thirty patients receiving cytotoxic chemotherapy were tested, and 13 of these patients followed serially. Fifteen patients post-autologous or allogeneic transplant were followed daily for platelet count and IPF percentage to monitor platelet recovery. The method demonstrates good reproducibility and stability. The recovery phase of thrombocytopenia in most chemotherapy and transplant patients was preceded by a rise in IPF percentage several days prior to platelet recovery. In particular, patients undergoing autologous transplantation (n = 8) using peripherally collected stem cells have a characteristic IPF percentage motif, with a rise one or two days prior to engraftment. The automated IPF is a useful parameter in the clinical evaluation of the thrombocytopenic patient and has the potential to allow optimal transfusion of platelet concentrates.

Pretransfusion trigger platelet counts and dose for prophylactic platelet transfusions

PURPOSE OF REVIEW

To assess critically both the blood platelet counts that prompt a platelet transfusion (i.e. trigger) in various clinical settings in patients with thrombocytopenia caused by marrow failure and the dose of platelets infused (i.e. number per each transfusion) for optimal hemostasis, feasibility, and safety.

RECENT FINDINGS

Definitive studies (e.g. well-designed, prospective, randomized clinical trials) are not available either historically or at present to support evidence-based decisions. Instead, retrospective reviews and anecdotal reports provide observational data to assist in best guess clinical practices.

SUMMARY

Reasonable clinical practice, until more definitive data become available, is to transfuse enough platelets per each transfusion to maintain the blood platelet count >10 x 10/L in stable nonbleeding patients, >20 x 10(9)/L in unstable nonbleeding patients, and >50 x 10(9)/L in bleeding patients or in those undergoing invasive procedures.

A therapeutic platelet transfusion strategy is safe and feasible in patients after autologous peripheral blood stem cell transplantation

Prophylactic platelet transfusions are considered as standard in most hematology centers, but there is a long-standing controversy as to whether standard prophylactic platelet transfusions are necessary or whether this strategy could be replaced by a therapeutic transfusion strategy. In 106 consecutive cases of patients receiving 140 autologous peripheral blood stem cell transplantations, we used a therapeutic platelet transfusion protocol when patients were in a clinically stable condition. Platelet transfusions were only used when relevant bleeding occurred (more than petechial). Median duration of thrombocytopenia <20 x 10(9)/l and <10 x 10(9)/l was 6 and 3 days, which resulted in a total of 989 and 508 days, respectively. In only 26 out of 140 transplants (19%), we observed clinically relevant bleeding of minor or moderate severity. No severe or life-threatening bleeding was registered. The median and mean number of single donor platelet transfusions was one per transplant (range 0-18). One-third of all transplants, and 47% after high-dose melphalan could be performed without any platelet transfusion. Compared with a historical control group, we could reduce the number of platelet transfusions by one half. This therapeutic platelet transfusion strategy can be performed safely resulting in a considerable reduction in prophylactic platelet transfusions.

Colony stimulating factors for prevention of myelosupressive therapy induced febrile neutropenia in children with acute lymphoblastic leukaemia

BACKGROUND

Acute lymphoblastic leukaemia (ALL) is the most common cancer in childhood and febrile neutropenia is a potentially life-threatening side effect of its treatment. Current treatment consists of supportive care plus antibiotics. Clinical trials have attempted to evaluate the use of colony-stimulating factors (CSF) as additional therapy to prevent febrile neutropenia in children with ALL. The individual trials do not show whether there is significant benefit or not. Systematic review provides the most reliable assessment and the best recommendations for practice.

OBJECTIVES

To evaluate the safety and effectiveness of the addition of G-CSF or GM-CSF to myelosuppressive chemotherapy in children with ALL, in an effort to prevent the development of febrile neutropenia. Evaluation of number of febrile neutropenia episodes, length to neutrophil count recovery, incidence and length of hospitalisation, number of infectious disease episodes, incidence and length of treatment delays, side effects (flu-like syndrome, bone pain and allergic reaction), relapse and overall mortality (death).

SEARCH STRATEGY

The search covered the Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, CANCERLIT, LILACS, and SciElo. We manually searched records of conference proceedings of ASCO and ASH from 1985 to 2003 as well as databases of ongoing trials. We consulted experts and scanned references from the relevant articles.

SELECTION CRITERIA

We looked for randomised controlled trials (RCTs) comparing CSF with placebo or no treatment as primary or secondary prophylaxis to prevent febrile neutropenia in children with ALL.

DATA COLLECTION AND ANALYSIS

Two authors independently selected, critically appraised studies and extracted relevant data. The end points of interest were:* Primary end points: number of febrile neutropenia episodes and overall mortality (death) * Secondary end points: time to neutrophil count recovery, incidence and length of hospitalisation, number of infectious diseases episodes, incidence and length of treatment delays, side effects (flu-like syndrome, bone pain and allergic reaction) and relapse. We conducted a meta-analysis of these end points and expressed the results as Peto odds ratios. For continuous outcomes we calculated a weighted mean difference and a standardised mean difference. For count data, meta-analysis of the logarithms of the rate ratios using generic inverse variance was employed.

MAIN RESULTS

We scanned more than 5500 citations and included six studies with a total of 332 participants in the analysis. There were insufficient data to assess the effect on survival. The use of CSF significantly reduced the number of episodes of febrile neutropenia episodes (Rate Ratio = 0.63; 95% confidence interval (CI) 0.46 to 0.85; p =0.003, with substantial heterogeneity), the length of hospitalisation (weighted mean difference (WMD) = -1.58; 95% CI -3.00 to -0.15; p = 0.03), and number of infectious diseases episodes (Rate Ratio=0.44; 95%CI 0.24 to 0.80; p=0.002). In spite of these results, CSF did not influence the length of episodes of neutropenia (WMD = -1.11; 95% CI -3.55 to 1.32; p = 0.4) or delays in chemotherapy courses (Rate Ratio=0.77; 95%CI 0.49 to 1,23; p=0.28) .

AUTHORS' CONCLUSIONS

Children with ALL treated with CSF benefit from shorter hospitalisation and fewer infections. However, there was no evidence for a shortened duration of neutropenia nor fewer treatment delays, and no useful information about survival. The role of CSF regarding febrile neutropenia episodes is still uncertain. Although current data shows statistical benefit for CSF use, substantial heterogeneity between included trials does not allow this conclusion.

Fresh frozen plasma prepared with amotosalen HCl (S-59) photochemical pathogen inactivation: transfusion of patients with congenital coagulation factor deficiencies

BACKGROUND

Photochemical treatment (PCT) with amotosalen HCl (S-59) was developed to inactivate pathogens and white blood cells in plasma (PCT-FFP) used for transfusion support.

STUDY DESIGN AND METHODS

An open-label, multicenter trial was conducted in patients with congenital coagulation factor deficiencies (factors [F]I, FII, FV, FVII, FX, FXI, and FXIII and protein C) to measure the kinetics of specific coagulation factors, hemostatic efficacy, and safety of PCT-FFP. Posttransfusion prothrombin time (PT), partial thromboplastin time (PTT), and clinical hemostasis were evaluated before and after PCT-FFP transfusions.

RESULTS

Thirty-four patients received 107 transfusions of PCT-FFP for kinetic studies or therapeutic indications (mean dose, 12.8 +/- 8.5 mL/kg). Incremental factor recoveries ranged from 0.9 to 2.4 IU per dL per IU per kg (FII, FV, FVII, FX, FXI, and protein C). Mean pretransfusion PT (20.7 +/- 22.2 sec) corrected after PCT-FFP (13.8 +/- 2.4 sec, p < 0.001). Mean pretransfusion PTT (51.2 +/- 29.3 sec) corrected after PCT-FFP (32.0 +/- 5.1 sec, p < 0.001). Thirteen patients required 77 transfusions for therapeutic indications. PCT-FFP provided effective hemostasis and was well tolerated.

CONCLUSIONS

Replacement coagulation factors in PCT-FFP exhibited kinetics and therapeutic efficacy consistent with conventional FFP.

A prospective randomized trial of a prophylactic platelet transfusion trigger of 10 x 109 per L versus 30 x 109 per L in allogeneic hematopoietic progenitor cell transplant recipients

BACKGROUND

The impact of lowering the platelet (PLT) count threshold for prophylactic PLT transfusion on bleeding and PLT use in allogeneic hematopoietic progenitor cell (HPC) transplant recipients is a matter of debate.

STUDY DESIGN AND METHODS

In 166 patients, randomly assigned to receive prophylactic PLT transfusion at a trigger level less than 10 x 10(9) PLTs per L (T10; n = 79) or less than 30 x 10(9) per L (T30; n = 87), the number of PLT and red blood cell (RBC) transfusions given and the number of hemorrhagic events (WHO Grades 2-4) were recorded.

RESULTS

No significant differences were found between the two groups regarding the clinical outcome variables (i.e., bacteremia, engraftment, graft-vs.-host disease [GVHD], hospital stay, death, and survival) or in the median total number of RBC transfusions given. The incidence, in Group T10 18 percent (14/79) and in Group T30 15 percent (13/87), as well as the type of bleeding were comparable. No deaths were attributed to hemorrhages. The number of PLT units transfused, however, was significantly lower in Group T10 (median, 4; range, 0-32), than in Group T30 (median, 10; range, 0-48; p < 0.001). Apart from the trigger level, the day of engraftment, the presence of acute GVHD, or bacteremia also affected the number of PLT transfusions.

CONCLUSION

A prophylactic PLT transfusion trigger level of less than 10 x 10(9) PLTs per L instead of less than 30 x 10(9) PLTs per L in allogeneic HPC transplant recipients was found to be safe and resulted in a decreased use of PLTs.

Transfusion management strategies: a survey of practicing pediatric hematology/oncology specialists

BACKGROUND

Little is known about the criteria used by pediatric oncologists for the transfusion of red blood cells and platelets to pediatric oncology patients.

PROCEDURE

Data regarding red blood cell and platelet transfusion practices were collected with an internet-based survey of physician members of the American Society for Pediatric Hematology/Oncology (ASPH/O). Respondents were asked to define platelet and red blood cell transfusion thresholds in a variety of clinical scenarios, and to describe criteria for dealing with cytomegalovirus (CMV) transmission from blood products, platelet dosing strategies, and prevention of RhD alloimmunization.

RESULTS

The overall response rate was 31.4% (264 of 841). Of the respondents, 76% indicated that their institution had defined criteria for acceptable transfusion practice; of these respondents, 114 (57%) indicated that there were special guidelines for pediatric oncology patients. Examination of the distribution of threshold platelet counts and hemoglobin levels that would prompt transfusion indicated a wide range of transfusion practice in commonly encountered clinical scenarios. Similar variability in practice was evident in platelet dosing strategies, CMV prevention strategies, and in the use of anti-D in RhD-negative patients who received RhD-positive platelets.

CONCLUSIONS

This current survey demonstrates that transfusion practices vary widely among pediatric hematology/oncology specialists and that prospective clinical trials may be necessary to determine optimal criteria for blood product support in pediatric oncology patients.

Adult acute lymphoblastic leukaemia

Acute lymphoblastic leukaemia (ALL) in adults is a relatively rare neoplasm with a curability rate around 30% at 5 years. This consideration makes it imperative to dissect further the biological mechanisms of disease, in order to selectively implement an hitherto unsatisfactory success rate. The recognition of discrete ALL subtypes (some of which deserve specific therapeutic approaches, like T-lineage ALL (T-ALL) and mature B-lineage ALL (B-ALL)) is possible through an accurate combination of cytomorphology, immunophenotytpe and cytogenetic assays and has been a major result of clinical research studies conducted over the past 20 years. Two-three major prognostic groups are now easily identifiable, with a survival probability ranging from <10 to 20% (Philadelphia-positive ALL) to about 50-60% (low-risk T-ALL and selected patients with B-lineage ALL). These issues are extensively reviewed and form the basis of current knowledge. The second major point relates to the emerging importance of studies that reveal a dysregulated gene activity and its clinical counterpart. It is now clear that prognostication is a complex matter ranging from patient-related issues to cytogenetics to molecular biology, including the evaluation of minimal residual disease (MRD) and possibly gene array tests. On these bases, the role of a correct, highly personalised therapeutic choice will soon become fundamental. Therapeutic progress may be obtainable through a careful integration of chemotherapy, stem cell transplantation, and the new targeted treatments with highly specific metabolic inhibitors and humanised monoclonal antibodies.

Strategies for transfusion therapy

Transfusion of allogeneic red blood cells (RBCs), fresh frozen plasma (FFP) and platelets is associated with risks, and outcome studies comparing liberal and restrictive transfusion regimens are lacking in surgical patients. Therefore, guidelines have been established. They recommend first maintaining normovolaemia by the use of crystalloids and colloids. RBC transfusions are recommended for haemoglobin levels < 6 g/dl and for physiological signs of inadequate oxygenation such as haemodynamic instability, oxygen extraction > 50% and myocardial ischaemia (new ST-segment depressions > 0.1 mV, new ST-segment elevations > 0.2 mV or new wall motion abnormalities in transoesophageal echocardiography). FFP transfusions are recommended for urgent reversal of anticoagulation, known coagulation factor deficiencies, microvascular bleeding in the presence of elevated (> 1.5 times normal) prothrombin time (PT) or partial thromboplastin time (PTT) and microvascular bleeding after the replacement of more than one blood volume when PT or PTT cannot be obtained. Platelet transfusions are recommended prior to major operations in patients with platelet counts < 50,000/microl, intraoperatively with microvascular bleeding at platelet counts < 50,000/microl and in the range of 50,000-100,0000/microl following cardiopulmonary bypass and in patients undergoing surgery where already minimal bleeding may cause major damage such as in neurosurgery.

Prophylactic platelet transfusion for haemorrhage after chemotherapy and stem cell transplantation

BACKGROUND

Platelet transfusions are used in modern clinical practice to prevent and treat bleeding in thrombocytopenic patients with bone marrow failure. Although considerable advances have been made in platelet transfusion therapy in the last 30 years, some areas continue to provoke debate, especially the use of prophylactic platelet transfusions for the prevention of thrombocytopenic bleeding.

OBJECTIVES

To determine the optimal use of platelet transfusion for the prevention of haemorrhage (prophylactic platelet transfusion) in patients with haematological malignancies undergoing chemotherapy or stem cell transplantation.

SEARCH STRATEGY

Randomised controlled trials (RCTs) were searched for in the Cochrane Central Register of Controlled Trials (CENTRAL). Searching was also undertaken on the OVID versions of MEDLINE and EMBASE using an RCT search filter strategy.

SELECTION CRITERIA

Randomised controlled trials involving transfusions of platelet concentrates, prepared either from individual units of whole blood or by apheresis, and given prophylactically to prevent bleeding in patients with haematological malignancies and receiving treatment with chemotherapy and/or stem cell transplantation.

DATA COLLECTION AND ANALYSIS

All electronically derived citations and abstracts of papers identified by the review search strategy were initially screened for relevancy by one reviewer. Studies clearly irrelevant were excluded at this stage. The full text of all potentially relevant trials was then formally assessed for eligibility by two reviewers independently. Two reviewers completed data extraction independently. Missing data were requested from the original investigators, as appropriate. Disagreements were resolved by discussion with the other reviewers.

MAIN RESULTS

Eight completed published trials, with a total of 390 participants in the intervention groups and 362 participants in the control groups, were included in the review for further analysis. The eight studies were classified as: * three trials relevant to prophylactic platelet transfusions versus therapeutic platelet transfusions; * three trials relevant to prophylactic platelet transfusion with one trigger level versus prophylactic platelet transfusion with another trigger level; * two trials relevant to prophylactic platelet transfusion with one dose schedule versus prophylactic platelet transfusion with another dose schedule. The few reports of controlled trials addressing prophylactic versus therapeutic transfusions contained small numbers of patients and were all undertaken over 25 years ago. None of these three studies explicitly clarified whether the lack of a reported difference was a reflection of insufficient power in the trials. The findings of the meta-analyses for this group of three small studies must be interpreted with caution. In contrast, more contemporary trials addressed the question of what platelet count thresholds should apply for prophylactic transfusion; three identified studies broadly compared platelet transfusion thresholds of 10 versus 20 x 109/litre for different clinical groups of patients. There were no statistically significant differences between the groups with regards to mortality, remission rates, number of participants with severe bleeding events or red cell transfusion requirements. However, it was unclear whether the studies had sufficient power to demonstrate in combination non-inferiority in terms of safety of the lower threshold, 10 x 109/litre. Insufficient randomised trials have been undertaken to make clinically relevant conclusions about the effect of different platelet doses.

REVIEWERS' CONCLUSIONS

There are no reasons to change current practice but uncertainty about the practice of prophylactic transfusion therapy should be recognised, particularly in the light of concerns about the scenario that blood products, including platelets, could become an increasingly scarce resource in the future and for which adequate alternatives do not exist. Consideration should be given to developing adequately powered trials comparing strategies of prophylaxis versus therapeutic platelet transfusion.

Optimizing platelet transfusion therapy

Platelet transfusions are widely used. Prophylactic transfusions are employed in severely thrombocytopenic patients without evidence of bleeding, but no randomized trial data prove the safety or efficacy of this approach. Randomized trials have demonstrated the equivalence of transfusion triggers of 10,000 and 20,000/microl for prophylactic transfusions. The former threshold is potentially safer for the patient, conservative of donor resources and leads to lower costs, with perhaps a slightly greater risk of minor hemorrhage. Randomized trials have demonstrated the equivalence of pheresis or whole blood-derived platelet transfusions. The former present a lower risk for infectious agents, and the latter are less expensive and a more efficient use of limited donor resources. Randomized trials prove that leukoreduced and ABO identical platelet transfusions reduce the risks of HLA alloimmunization and platelet transfusion refractoriness (both leukoreduction and ABO matching), transfusion reactions (leukoreduction) and CMV transmission (leukoreduction). Leukoreduction and ABO matching of platelet transfusions also have been associated in preliminary observational studies with reduced morbidity and mortality in surgical patients and reduced infections in patients with leukemia. These results require further investigation. Future challenges include (1) determining the best approach to bacterial contamination of platelets, whether by detection methods or pathogen inactivation and (2) determining the threshold for prophylactic platelet transfusions in thrombocytopenic patients undergoing surgery or invasive procedures.