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

Therapeutic efficacy of pooled buffy-coat platelet components prepared and stored with a platelet additive solution

Despite the introduction of platelet additive solutions for the preparation of pooled platelet components, only a few studies of limited scope have evaluated the clinical efficacy of platelets stored in these solutions. The current report presents an analysis of data to evaluate the response to the transfusion of pooled buffy-coat components suspended in storage solution with reduced (35%) plasma content in comparison with 100% plasma products. During the euroSPRITE clinical trial of platelet components treated with a pathogen inactivation process, control treatment group platelet components were prepared in 100% allogeneic donor plasma (plasma control) or in platelet additive solution (T-Sol) mixed with plasma (T-Sol control). Control group thrombocytopenic patients received either plasma control or T-Sol control platelet components. One-hour and 24-h platelet count increments (CIs) and corrected count increments (CCIs) were analysed for these two types of preparation. In addition, haemostatic assessments were conducted for each transfusion. One-hour and 24-h mean platelet CIs and post-transfusion haemostatic scores were not significantly different for patients receiving platelet components suspended in 100% plasma and T-Sol plasma mixtures. Pooled buffy-coat platelet components prepared in reduced plasma content mixtures provided therapeutic platelet CIs with effective haemostasis.

Methods for the analysis of bleeding outcomes in randomized trials of PLT transfusion triggers

BACKGROUND

A number of methodologic challenges arise in the analysis of bleeding data from clinical trials of PLT transfusion triggers. It is important to understand the assumptions and role of the various methods of analysis to interpret published trials and to design future studies appropriately.

STUDY DESIGN AND METHODS

The methods of analysis used for testing the effectiveness and safety of transfusion strategies are reviewed from several recent PLT transfusion trigger trials. The underlying assumptions of these methods are discussed, as well as the clinical interpretations of the resulting summary statistics. Four methods of analysis were applied to data from a large PLT transfusion trigger study to illustrate the differences in the interpretations that can arise from various approaches.

RESULTS

PLT transfusion trigger trials of patients with leukemia have based their primary analyses on 1) simple dichotomous classifications of whether or not at least 1 day of clinically important bleeding was experienced; 2) the time to the first day of clinically important bleeding; and 3) the proportion of days at risk with clinically important bleeding. Recurrent event methods provide a robust alternative approach to the analysis of this kind of data and should be considered if interest is in capturing the overall burden of bleeding over time. These four methods differ in the extent to which they utilize information on the number of days with bleeding and the temporal variation in bleeding patterns. Inferences drawn regarding the relative safety and efficacy of different transfusion triggers can vary depending on the method of analysis.

CONCLUSION

To rigorously design and analyze future PLT transfusion studies based on bleeding outcomes, it is important to have a clear understanding of the interpretation of the different ways of analyzing bleeding outcomes. The analysis strategy should be selected based on the clinical question being addressed.

Thrombocytopenia and hemorrhagic risk in cancer patients

In patients with malignant diseases, despite a direct relationship between the level of platelet count and bleeding episodes, it is evident that the risk of bleeding depends not only on the platelet count, but also on the underlying disease, the use of drugs interfering with platelet function and complications such as fever and infection or the presence of coagulation defects. As a consequence, it is not only the absolute platelet count, but rather the number of functional platelets that is important for the prevention of bleeding. As for Prophylaxis of hemorrhagic risk in these setting of patients, studies have now convincingly demonstrated that a 10,000/microL threshold for prophylactic platelet transfusion is safe and effective in uncomplicated thrombocytopenic patients. However, a threshold of 20,000/microL must be considered only for patients with high fever, hyperleukocytosis, coagulation abnormalities or who necessitate of invasive procedure. Moreover, as suggested by the clinical practice guidelines of the American Society of Clinical Oncology, a threshold of 20,000/microL must be considered for patients receiving aggressive therapy for bladder tumors and for those with demonstrated necrotic tumors.

Updates in perioperative coagulation: physiology and management of thromboembolism and haemorrhage

Understanding of blood coagulation has evolved significantly in recent years. Both new coagulation proteins and inhibitors have been found and new interactions among previously known components of the coagulation system have been discovered. This increased knowledge has led to the development of various new diagnostic coagulation tests and promising antithrombotic and haemostatic drugs. Several such agents are currently being introduced into clinical medicine for both the treatment or prophylaxis of thromboembolic disease and for the treatment of bleeding. This review aims to elucidate these new concepts and to outline some consequences for clinical anaesthesia and perioperative medicine.

Triggers for prophylactic use of platelet transfusions and optimal platelet dosing in thrombocytopenic dogs and cats

Prophylactic platelet transfusions are frequently given to human patients with hypoproliferative thrombocytopenia. For several decades, the most common transfusion trigger was 20,000/microL, but the trend is now to use 10,000/microL in the absence of other risk factors for bleeding. This trigger seems to reduce the number of transfusions without increasing the risk of severe bleeding. Most studies involved in establishing platelet transfusion policies have involved patients with acute leukemia, with fewer studies involving patients undergoing hematopoietic stem cell transplantation or aggressive chemotherapy for other cancers and patients with aplastic anemia. In the presence of other risk factors for spontaneous bleeding, 20,000/microL is still considered an appropriate trigger. The trigger for prophylactic transfusion before surgery has not undergone the same recent scrutiny as has the trigger for spontaneous bleeding. The recommendation remains to raise the platelet count to 50,000 to 100,000/microL if possible, although it is recognized that surgery and other invasive procedures have been performed at lower platelet counts without major bleeding. Prophylactic transfusion is not used in disorders of platelet consumption and destruction to prevent spontaneous bleeding but is used before surgery. Because of the comparative lack of experience with platelet transfusion in veterinary medicine, it is difficult to make generalizations for dogs and cats. Using the guidelines established for therapeutic and prophylactic transfusion of human patients is a reasonable starting point, however. A therapeutic transfusion policy is suggested in the veterinary setting provided that the patient can be closely observed for critical bleeding and a prompt transfusion can be given. This policy should ultimately reduce the overall number of platelet transfusions given to hospital patients. If an animal cannot be closely observed or the ability to transfuse on demand is limited, prophylactic transfusion is recommended. The triggers for initiating a platelet transfusion in dogs are extrapolated from human data; these values are lower by 50% for cats. Because of the imprecision of platelet counting at low values, platelet counts must always be interpreted in conjunction with clinical signs of hemorrhage. If platelet-rich plasma or platelet concentrate is available, a dose of 1 platelet unit per 10 kg is recommended, although resources may dictate a smaller dose. This will raise the recipient platelet count by a maximum of about 40,000/microL. Assuming a trigger of 10,000/microL, a transfusion will probably be required approximately every 3 days. It must be remembered that the frequency of platelet transfusions may be greater in the presence of factors accelerating platelet loss or destruction. If fresh whole blood is used, a rule of thumb is to transfuse 10 mL/kg, which will raise the recipient platelet count by a maximum of approximately 10,000/microL. Daily transfusions or transfusions every other day will probably be required.

Universal prestorage leukoreduction in Canada decreases platelet alloimmunization and refractoriness

Randomized controlled trials have shown a reduction in platelet alloimmunization and refractoriness in patients with acute leukemia (AL) with the use of poststorage leukoreduction of blood products. Universal prestorage leukoreduction (ULR) of red cell and platelet products has been performed in Canada since August 1999. We conducted a retrospective analysis of 13 902 platelet transfusions in 617 patients undergoing chemotherapy (CT) for AL or stem cell transplantation (SCT) before (n = 315) and after (n = 302) the introduction of ULR. Alloimmunization was significantly reduced (19% to 7%, P <.001) in the post-ULR group. Alloimmune platelet refractoriness was similarly reduced (14% to 4%, P <.001). Fewer patients in the post-ULR group received HLA-matched platelets (14% vs 5%, P <.001). Alloimmunization and alloimmune refractoriness in the 318 patients who were previously pregnant and/or transfused were also reduced after ULR (P =.023 and P =.005, respectively). In a Cox regression model, the 3 independent factors that predicted for alloimmune refractoriness were nonleukoreduced blood products (relative risk [RR], 2.2 [95% CI, 1.2-4.3]), a history of pregnancy and/or transfusion (RR, 2.3 [95% CI, 1.3-4.2]), and receipt of 13 or more platelet transfusions (RR, 6.0 [95% CI, 2.4-15.3]). In conclusion, ULR reduces alloimmunization, refractoriness, and requirements for HLA-matched platelets when applied as routine transfusion practice to patients receiving CT or SCT.

Investigation and management of newly diagnosed childhood idiopathic thrombocytopenic purpura: problems and proposed solutions

The purpose of this paper is to describe current problems in investigation and management of newly diagnosed childhood idiopathic thrombocytopenic purpura (ITP). An Intercontinental Childhood ITP Study Group was established in 1997 with the aim to promote international clinical research based on a research environment and network of physicians. Initial and still ongoing projects include registries to collect data on the natural history of ITP, demographics of patients with ITP, and its management. Registry I was successful, with data on almost 3,000 patients from 38 countries. Registry II investigates the occurrence and severity of bleeding at the time of diagnosis and within 2 years of follow-up. Current problems are listed and discussed. An international network of physicians similar to that of malignant diseases for the conduct of clinical research and regular scientific meetings is the basis for solutions of the identified problems.

Component therapy

The dramatic advances that have taken place in recent years in the care of sick and premature infants also have been matched by a similar increase in the use of blood transfusion therapy. Haematological features indicate that a newborn has a blood volume of 85-125 ml/kg the foetal haemoglobin is 60-85% and average Hb in full term infant is 18 gm/dl. By 2-3 months it falls to 11-12 g/dl the main cause of anemia are iron poor diet, weaning diets recurrent or chronic infections and hemolytic episodes in malarious areas. The red cells transfusions are usually top up transfusions, exchange transfusions, partial exchange transfusions. Top up- are for investigational losses and correction of mild degrees of anemias, upto to 5-15 ml/kg. They comprise 90% of all neonatal transfusions and are used in low birth babies in special care units for a maximum of 9-10 episodes. The walk in donor programs once popular are not much in vogue. The threshold for transfusion is 8-10 g/dl Hb for upto 5 weeks. Exchange transfusions are done for correction of anemia, removal of bilirubin, removal of antibodies and replacement of red cells. Ideally plasma reduced red cells that are not older than 5 days are used. It is prepared by removal of 120 ml of standard whole blood donation. The advantage of fresh cells is that hyperkalemia is avoided and good post transfusion survival acceptable red cell oxygen affinity. However it has to be screened for sickle cell disease and G6PD deficiency. Indications for exchange transfusion are kernicterus, neonatal hemolysis, G6PD deficiency, ARDS, neonatal sepsis, DIC and neonatal isoimmune thrombocytopaenia. Complications include over transfusion, perforation of major vessels, hypocalcaemia, citrate toxicity, hypothermia, hypoglycaemia, thrombocytopenia, necrotizing enterocolitis, GVHD, bacterial, viral infections. Partial exchange transfusions are done for symptomatic anemia, where Hb<10 g/dl, it is indicated in polycythemia and hyperviscosity syndromes. Exchange volume = Blood volume x (observed Hct-Desired HCt) divided observed Hct. Points to consider-there is weak expression of ABO antigens so particular care while grouping. Transfusing volumes should be 2-5 ml/kg/hour in paediatric bags of 50-100 ml with infusion devices. Platelet transfusion are indicated in neonatal throbocytopaenia, thrombocytopaenia due to sepsis, DIC, bacterial pathogens, CMV, TORCHS, Obstetric conditions such as pre eclampsia, intrauterine death abruption placenta birth injury hypoxia schock neonatal iso immune thrombocytopaenia and maternal ITP. Administration 1 RDE/pack per 2.5 kg single dose of fresh platelets less than 24hrs which contains 55 x 10(9) cells. This also contributes fresh plasma so is useful for coagulation defects also, though there is a risk of CMV and GVHD due to leucocyte contamination. Granulocyte concentrate; Gravity leucopheresis-1:8 ratio of 60 ml of 6% HES made to stand for 1hr.

Prophylactic platelet transfusions: which dose is the best dose? A review of the literature

Routine platelet transfusions for patients with acute leukemia were introduced in the early 1960s, and since then platelet use has increased steadily. Despite widespread use, good clinical evidence supporting prophylactic platelet transfusions is limited, and there are very few studies that have examined the dose for prophylactic platelet transfusions. Review of the platelet dose used in both early studies of routine platelet transfusions and more recent clinical trials of platelet transfusions shows wide variation in dosing, which is also reflected in clinical practice. As such, only limited recommendations for platelet dose have been forthcoming from consensus conferences or guidelines. The results from 3 recent clinical trials and a mathematical model examining the dose for prophylactic platelet transfusions suggest that lower dose transfusions may decrease the total number of platelets transfused; however, no definitive conclusions about the optimal platelet dose can be reached as these trials were not designed to evaluate bleeding outcomes or total platelet utilization. Future large clinical trials of platelet dose, which examine these critical outcomes, are required. Only with these results can the optimal platelet dose be determined.

Methodologic issues in the use of bleeding as an outcome in transfusion medicine studies

BACKGROUND

Prophylactic platelet transfusions are given to thrombocytopenic patients to prevent bleeding. The benefit of platelet transfusions has frequently been assessed by measuring the count increment; however, more recently, an assessment of bleeding has been used because it is a more clinically relevant outcome measure. The purpose of this study was to identify platelet transfusion trigger studies that used bleeding as an outcome measure, compare and contrast methods used to document bleeding and analyze bleeding outcomes, and identify and discuss methodologic issues to consider when bleeding is used as a study outcome.

STUDY DESIGN AND METHODS

A systematic search to identify platelet transfusion trigger studies was performed. Relevant articles were reviewed to identify how bleeding data was captured and analyzed, and methodologic considerations were identified.

RESULTS

Seven articles meeting the predefined entry criteria were identified. Methods used to document bleeding included chart review and clinical assessment. The frequency of assessment and the type of personnel performing the assessment were variable. Four approaches to analysis were identified: descriptive; comparison of the proportions of patients having at least one bleed; comparison of patient days with bleeding expressed as a proportion of the total days at risk of bleeding; and time-to-event (first bleed) analysis.

CONCLUSION

Methodologic issues for consideration when designing a clinical study with bleeding as the outcome measure included approaches to minimize bias in the documentation and classification of bleeding and selection of an analysis approach that is appropriate to the question being asked. The need for development of a valid and reliable bleeding scale was also identified.

Immunoplatelet counting: potential for reducing the use of platelet transfusions through more accurate platelet counting

Research is required to determine the optimal approach for prophylactic platelet transfusions in patients with haematological malignant disorders. It has been suggested that thresholds for prophylactic platelet transfusions of platelet counts below 10 x 109/l should be investigated, as these may be equivalent in clinical effectiveness and associated with lower costs and fewer complications. An important concern in such investigation is the accurate estimation of platelet counts below 10 x 109/l. This study aimed to further examine the potential reduction in platelet usage that could be made if a lowered platelet transfusion threshold of 5 x 109/l was used in conjunction with an immunoplatelet counting method. Clinical and laboratory data from 130 haematology patients were used. Standard platelet counting was performed using Bayer H3 and ABX Argos analysers. Immunoplatelet counting was performed by flow cytometry using anti-CD61. The potential for reducing platelet transfusions included consideration of clinical criteria that influence prophylactic platelet transfusion use. The results indicated that the use of an immunoplatelet count with a 5 x 109/l platelet transfusion threshold would potentially reduce the number of transfusions by 10.4% in comparison with a 10 x 109/l threshold and standard automated platelet counting with the ABX Argos analyser, and increase the number of transfusions by 5.4% in comparison with the same threshold using the Bayer H3 analyser. The immunoplatelet count may aid the clinical decision to transfuse platelets, but would not necessarily lead to a reduced use of platelet transfusions.

Is automated platelet counting still a problem in thrombocytopenic blood?

CONTEXT

Reliable platelet counting is crucial for indicating prophylactic platelet transfusion in thrombocytopenic patients.

OBJECTIVE

To evaluate the precision and accuracy of platelet counting for thrombocytopenic patients, using four different automated counters in comparison with the Brecher & Cronkite reference method recommended by the International Committee for Standardization in Hematology (ICSH).

TYPE OF STUDY

Automated platelet counting assessment in thrombocytopenic patients.

SETTING

Hematology Laboratory, Hospital do Servidor Público Estadual de São Paulo, and the Hematology Division of Instituto Adolfo Lutz, São Paulo, SP, Brazil.

MAIN MEASUREMENTS

Brecher & Cronkite reference method and four different automated platelet counters.

PARTICIPANTS

43 thrombocytopenic patients with platelet counts of less than 30,000/microliter.

RESULTS

The ADVIA-120 (Bayer), Coulter STKS, H1 System (Technicom-Bayer) and Coulter T-890 automatic instruments presented great precision and accuracy in relation to laboratory thrombocytopenic samples obtained by diluting blood from normal donors. However, when thrombocytopenic patients were investigated, all the counters except ADVIA (which is based on volume and refraction index) showed low accuracy when compared to the Brecher & Cronkite reference method (ICSH). The ADVIA counter showed high correlation (r = 0.974). However, all counters showed flags in thrombocytopenic samples.

CONCLUSION

The Brecher & Cronkite reference method should always be indicated in thrombocytopenic patients for platelet counts below 30,000 plt/microliter obtained in one dimensional counters.

The frequency of bleeding complications in patients with haematological malignancy following the introduction of a stringent prophylactic platelet transfusion policy

Indications for platelet transfusion remain controversial and are frequently based on arbitrary numerical criteria. In October 2000, we introduced a stringent prophylactic-platelet transfusion policy < 10 x 109/l for stable patients and < 20 x 10(9)/l in the presence of major bleeding or additional risk factors. A trigger of < 50 x 10(9)/l was introduced for patients undergoing invasive procedures. A prospective analysis was performed measuring the frequency of minor and major bleeding events, morbidity, mortality and duration of pancytopenia. Blood product usage was assessed and health care savings measured. A total of 98 patients were evaluated on 2147 patient study days and 271 bleeding episodes were recorded. Major bleeding occurred on 1.39% (30/2147) of the study days when platelet counts were < 10 x 10(9)/l and 2.3% (50/2147) of the study days when platelet counts were 10-20 x 10(9)/l. In patients with platelets > 20 x 10(9)/l, there were 117 major bleeding episodes observed on 5.4% of the study days. In patients with no identified additional risk factors present, major haemorrhages were recorded in 0.51% (11/2147) of the study days in patients with platelet counts > or = 10 x 10(9)/l . There was a 36% reduction in platelet units transfused compared with retrospective data when an arbitrary transfusion trigger of 20 x 10(9)/l was in place (P = < 0.02). Of note, a 16% reduction in red cell transfusions was recorded. These data confirm that the introduction of a transfusion trigger of < 10 x 10(9)/l in the absence of fresh bleeding and sepsis (> 38 degrees C) is safe and has a significant impact on overall hospital transfusion costs.

What is the proper threshold for platelet transfusion in patients with chemotherapy-induced thrombocytopenia?

Platelet transfusion therapy is an integral part of modern oncological practice and is used to treat hemorrhage associated with thrombocytopenia. More commonly, platelets are transfused to prevent hemorrhage in thrombocytopenic patients. Conventional wisdom has suggested a threshold for prophylactic transfusion of <20x10(9)/l. Many studies now support the safety of more conservative transfusion regimes that reduce patient exposure to donors and conserve precious resources, without an increase in risk of hemorrhage. This review presents the data to support the use of a prophylactic transfusion threshold of <10x10(9)/l in patients without risk factors for hemorrhage and who have ready access to emergent medical care.

New strategies for prophylactic platelet transfusion in patients with hematologic diseases

There is an increasing demand for platelet transfusions due to intensive chemotherapy and blood stem cell or bone marrow transplantation for the treatment of hematologic and oncologic diseases. There has been a long-lasting debate over whether the traditional threshold for prophylactic platelet transfusion of 20,000/microl is really necessary to prevent hemorrhagic complications. During the last 10 years several studies with more than 1,000 patients together have proven the safety of a platelet transfusion trigger of 10,000/microl or even lower when patients are clinically stable without active bleeding. This experience has been mostly gathered in patients with acute leukemia. But this stringent platelet transfusion policy can be used also after blood stem cell and bone marrow transplantation. In stable patients with aplastic anemia and myelodysplasia, prophylactic transfusions should be replaced in most patients by a therapeutic transfusion strategy. Such restrictive platelet transfusion strategies decrease the risk of infectious disease transmission, immunization, and febrile transfusion reactions. Besides reduced hospital visits and a shorter hospital stay for the patients, the costs for platelet transfusions are lowered by 20%-30% compared with traditional transfusion strategies. The decision to administer platelet transfusions should incorporate individual clinical characteristics of the patients and not simply be a reflexive reaction to the platelet count. Further clinical studies are needed to answer the still open question of whether patients with acute leukemia should also be transfused therapeutically rather than prophylactically when they are in stable condition without signs of active bleeding.

Design of clinical trials to evaluate the efficacy of platelet transfusion: the euroSPRITE trial for components treated with Helinx technology

Methods of collection, preparation, and transfusion of platelet components have evolved markedly since the introduction of modern platelet transfusion therapy three decades ago. Despite these improvements, few randomized, prospective, controlled studies have been conducted to evaluate the effects of these innovations on the outcome of platelet transfusion--prevention and treatment of bleeding due to thrombocytopenia. The majority of studies have used posttransfusion platelet count increments (CIs) as the primary outcome variable rather than bleeding assessments. In general, these studies have only examined average values for platelet CIs or adjusted ratio measures such as corrected count increment (CCI). Because platelet transfusions are given repeatedly over variable periods of time, this type of analysis has not provided information about the effects of multiple platelet transfusions or about specific product or patient-related covariates that may impact the outcome. Longitudinal regression analysis of platelet CIs offers the potential to provide more information than simple average values of ratio measures. The euroSPRITE trial, a European, multicenter, phase III study undertaken to assess the clinical efficacy and safety of platelets prepared with Helinx technology (Cerus Corp, Concord, CA), used longitudinal regression analysis to characterize more fully the response to platelet transfusions with products prepared with this new pathogen inactivation technology. In contrast to previous studies, the euroSPRITE study examined peritransfusion hemostasis and global indices of hemostasis to correlate the effect of platelet CI with prevention and treatment of bleeding during a period of platelet transfusion support.

Acute bleeding complications in patients after bone marrow transplantation

Acute bleeding is a frequent complication that commonly associates with increased morbidity after bone marrow transplantation. Except for diffuse alveolar hemorrhage and cerebral hemorrhage, bleeding is infrequently recorded as a direct cause of death. Yet outcome analyses showed that bleeding from any reviewed site was associated with reduced survival. Reduced survival was correlated with bleeding intensity and the number of bleeding sites. These data point to the need to monitor all manifestations of bleeding, as bleeding may identify patients at risk for bone marrow transplantation toxicity. Until recently, prophylactic platelet transfusions were commonly given at a trigger of 20 x 10(9)/L. Whereas bleeding is more likely to occur when platelet counts drop to low levels, most bleeding episodes were recorded with platelet counts greater than 20 x 10(9)/L, suggesting causes other than profound thrombocytopenia in the pathogenesis of bleeding. Given that a trigger of 10 x 10(9)/L has become accepted for prophylactic platelet transfusions, care should be taken to ensure that parameters other than the incidence of bleeding have not been adversely affected.

Revisitation of the clinical indications for the transfusion of platelet concentrates

Platelet transfusion is indicated when the expected benefits of increasing the number of functional platelets in the patient's circulation outweigh the potential risks generated by exposing the patient to allogeneic, manipulated and stored blood products such as platelet concentrates. Although reassuring evidence has been collected indicating that current risks associated with blood transfusion are lower than those of several voluntary and involuntary human activities, balancing benefits and risks of platelet transfusion may not be easy in a proportion of patients and in a number of conditions. To facilitate this task, guidelines have been developed, with particular attention to cancer patients. As witnessed by the most recent guidelines, over the last few years there has been a progressive, although not absolute, consensus on: (i) the routine use of platelets as a tool to prevent hemorrhage in oncohematology (the so called 'prophylactic approach') as opposed to limiting platelet transfusion to actual bleeding episodes (the so-called 'therapeutic approach') and (ii) lowering the trigger for prophylactic platelet transfusion in stable oncohematology recipients from 20 x 109 to 10 x 109 platelets/L. This has been accompanied by a reduction of platelet use per oncohematology patient of about 20%, an important outcome in view of the progressive increase of platelet demand due to more aggressive therapy in cancer patients. In selected clinical conditions, specific triggers ranging from 30 x 10(9) to 100 x 10(9) platelets/L have been recommended, with higher values when surgical procedures are required for the patient's treatment. Indications and trigger values proposed in the guidelines must be considered within the context of careful clinical evaluation of each patient, with a clear appreciation of the power of discrimination of automated platelet counters at low counts, and of the quality and local availability of platelet products for emergency.

Rehabilitation following bone marrow transplantation

Bone marrow transplantation and stem cell transplantation are increasingly used to treat hematologic malignancies and some solid tumors. The treatment entails bone marrow-ablative therapies and intensive medical support to sustain the patient through pancytopenia and other complications of the disease, transplantation process, or drug side effects. Patients who develop graft-versus-host disease are the most difficult subset of transplant recipients to manage. Most transplant recipients perform at normal or near-normal functional levels at the inception of the transplantation process but are at high risk for developing functional deficits as a result of cumulative impairments. These impairments arise from their disease, their prior cancer treatment, transplant induction, graft-versus-host disease, immobility, infection, steroid-related side effects, and other sequelae of transplantation. Preventive and preemptive rehabilitation interventions can minimize functional loss and facilitate recovery, but the transplantation team must be sensitive to and regularly assess for early functional declines in these patients. The physiatrist and the other members of the rehabilitation team must be thoroughly acquainted with the unique needs and challenges of the bone marrow transplantation population in order to design and modify treatment programs effectively and safely. Outcome research has shown that some patients have continued limitations in function despite successful transplantation. Few evidence-based data are available that addresses factors correlating with poor functional outcomes other than graft-versus-host disease. However, this disease has not been investigated utilizing objective functional instruments. Future research should more clearly elucidate the functional impact of allogeneic and autologous transplants by using standardized physical performance measures as well as thorough function-based symptomatology questionnaires.

Bleeding and thrombotic complications in critically ill patients with cancer

Alterations in hemostasis are common in patients with cancer admitted to the ICU. Depending on the underlying disease and specific hemostatic abnormality, the patient with cancer may develop bleeding, thrombosis, or both, such as DIC. Bleeding complications usually result from abnormalities in platelets or deficiency of coagulation factors and require specific blood or coagulation factor replacement. Similarly, critically ill patients with cancer are predisposed to thrombotic complications such as DVT, PE, and central vein thrombosis, the last as a result of the widespread use of long-term indwelling catheter devices. Advances in diagnostic imaging and the availability of newer and more potent anticoagulant agents have facilitated the care of these patients greatly. Ultimately, it is hoped that a thorough understanding of the various disturbances in hemostasis, innovative treatment approaches, and implementation of preventive strategies in patients with cancer will lead to decreased morbidity and improved survival rates of critically ill patients with cancer in the ICU.

Automated CD61 immunoplatelet analysis of thrombocytopenic samples

Revision of the current decision point for prophylactic platelet transfusion in thrombocytopenic patients requires the availability of a method that is able to provide accurate platelet counts to as low as 1 x 109/l. This study is the first to evaluate the immunoplatelet method (CD61-Imm) of the haematological analyser Cell-Dyn 4000 in direct comparison with the flow cytometric procedure. Additionally CD61-Imm results were compared with CD4000 optical (Plto) counts in the ranges 20-547 x 109/l (n = 127) and 1-35 x 109/l (n = 107). The immunoplatelet and Plto results were in good agreement between 20 x 109/l and 547 x 109/l, but for samples of < 25 x 109/l the Plto tended to overestimate the counts. We determined the limits of detection (LD) and quantification (LLQ) for all three methods using standard statistical procedures. The LD for the flow cytometric CD41a method was 0.02 x 109/l compared with 0.009 x 109/l and 1.73 x 109/l for the CD61-Imm and Plto methods respectively. The LLQCV = 15% for the CD41a method was 1.8 x 109/l compared with 1.6 x 109/l and 18.0 x 109/l for the CD61-Imm and Plto procedures. In conclusion, (i) the CD61-Imm method performance is at least equivalent to the reference flow cytometric method, and (ii) in severe thrombocytopenia the CD61-Imm count is superior to the Plto count.

An interlaboratory study of a candidate reference method for platelet counting

A multinational interlaboratory task force explored the important variables of platelet reference counting and developed a candidate flow cytometric reference method based on the RBC/platelet ratio. A multicenter comparison was performed to determine whether the method met the necessary criteria and was precise enough to be recommended as a new reference method. Each laboratory analyzed serial dilutions of normal specimens, stabilized material, and at least 60 patient specimens with a range of platelet counts from 1 to 400 x 10(3)/microL (1-400 x 10(9)/L). Pooled analysis of the serial dilutions showed that RBC-platelet and RBC-RBC coincidence events became negligible at sufficiently high dilutions (i.e., > 1:1,000). All laboratories demonstrated excellent intra-assay and acceptable interlaboratory precision. Two antibodies (CD61 and CD41) were used for identifying platelets and individually gave acceptable results, but in a minority of samples, staining differences were observed. The optimum method thus uses a double-labeling procedure with a final dilution factor of 1:1,000. The study demonstrated that this method meets the criteria for a reference platelet count.

Platelet transfusion for patients with cancer: clinical practice guidelines of the American Society of Clinical Oncology

OBJECTIVE

To determine the most effective, evidence-based approach to the use of platelet transfusions in patients with cancer.

OUTCOMES

Outcomes of interest included prevention of morbidity and mortality from hemorrhage, effects on survival, quality of life, toxicity reduction, and cost-effectiveness.

EVIDENCE

A complete MedLine search was performed of the past 20 years of the medical literature. Keywords included platelet transfusion, alloimmunization, hemorrhage, threshold and thrombocytopenia. The search was broadened by articles from the bibliographies of selected articles.

VALUES

Levels of evidence and guideline grades were rated by a standard process. More weight was given to studies that tested a hypothesis directly related to one of the primary outcomes in a randomized design. BENEFITS/HARMS/COST: The possible consequences of different approaches to the use of platelet transfusion were considered in evaluating a preference for one or another technique producing similar outcomes. Cost alone was not a determining factor.

RECOMMENDATIONS

Appendix A summarizes the recommendations concerning the choice of particular platelet preparations, the use of prophylactic platelet transfusions, indications for transfusion in selected clinical situations, and the diagnosis, prevention, and management of refractoriness to platelet transfusion.

VALIDATION

Five outside reviewers, the ASCO Health Services Research Committee, and the ASCO Board reviewed this document.

SPONSOR

American Society of Clinical Oncology

Lowering the prophylactic platelet transfusion threshold: a prospective analysis

The 20 x 10(9) /L threshold for prophylactic platelet transfusion may be unnecessarily high. Few prospective studies, however, in which other trigger values were tested have been published. In this study all hospitalized, thrombocytopenic adult hematology-oncology patients in our institution were prospectively evaluated daily for hemorrhage and platelet transfusion during a one year period; no patients were excluded for bleeding or infectious problems. By design, during the initial six-months (baseline period), the prophylactic platelet transfusion trigger was 20 x 10(9) /L; for the second six-months (study period) this threshold was changed to 10 x 10(9) /L. Patients studied during the two periods did not differ significantly in age, gender, diagnosis, blood or marrow transplant status, and duration of neutropenia. Compliance with the thresholds was 95.6% (baseline period) and 93.5% (study period). For patients with platelet counts under 20 x 10(9) /L, the mean use of platelet transfusions per patient per day was significantly lower in the study period (4.47) than in the baseline period (6.48; p<0.001). Both mean prophylactic (1.54/patient-day) and therapeutic (2.93/patient-day) platelet transfusions were reduced in the study period compared with the baseline period (2.26 and 4.22/patient-day, respectively). Hemorrhage was slightly reduced in the study period compared with the baseline period: major hemorrhage, 15.2% vs. 18.4% (p=0.014); minor hemorrhage, 63.6% vs. 70.1% (p<0.001). Thus, hemorrhage was not increased with the lower trigger level. A 10 x 10(9) /L prophylactic platelet transfusion threshold value is safe and effective.

The problem of thrombocytopenia after hematopoietic stem cell transplantation

Thrombocytopenia after hematopoietic stem cell transplantation (HSCT) is associated with an increased risk of bleeding and utilization of significant resources. This review presents an analysis of risk factors associated with delayed platelet engraftment. The retrospective analysis included 1,468 recipients of autologous or allogeneic transplants treated between January 1, 1990 and July 1, 1995. Risk factors associated with delayed platelet engraftment after autologous HSCT included use of marrow rather than peripheral blood as the source of stem cells, being transplanted for acute myeloid leukemia rather than other diseases, positive patient serology for cytomegalovirus and the presence of infection post-transplant before engraftment. Risk factors associated with delayed platelet engraftment after allogeneic marrow transplantation included unrelated as opposed to related donor transplants, being transplanted for diseases other than chronic myelogenous leukemia, increased age, onset of acute graft-versus-host disease (AGVHD), male gender, the administration of methotrexate for GVHD prophylaxis and the presence of infection before engraftment. Delayed platelet recovery is associated with decreased survival after both autologous and allogeneic transplants. Management of delayed platelet recovery by transfusion of blood products requires significant medical resources and is of some risk to the patients. Further development of new strategies may safely reduce the need for blood products. These include peripheral blood stem cell transplants (allogeneic and autologous), new algorithms for administering routine platelet transfusions and investigative biological agents for stimulating megakaryocytopoiesis. Further studies may elucidate the cause of increased platelet consumption associated with infection and GVHD.

FDA licensure of NEUMEGA to prevent severe chemotherapy-induced thrombocytopenia

This paper discusses background information and the body of clinical data that has been accumulated to demonstrate the efficacy and safety of NEUMEGA (recombinant human interleukin 11) when used to prevent severe chemotherapy-induced thrombocytopenia and reduce the need for platelet transfusions in patients with nonmyeloid malignancies. NEUMEGA is recommended to be used at a dose of 50 microg/kg s.c. once daily starting the day after chemotherapy ends until a platelet count of 50,000 cells/microl is achieved after the expected nadir.

Recombinant human thrombopoietin (rhTPO) after autologous bone marrow transplantation: a phase I pharmacokinetic and pharmacodynamic study

Thrombocytopenia following myelotoxic therapy is a common problem and when severe (<20,000/microl) can lead to severe morbidity and mortality. Thrombopoietin (TPO) is a naturally occurring glycosylated peptide which stimulates the differentiation of bone marrow stem cells into megakaryocyte progenitor cells, induces the expression of megakaryocyte differentiation markers, promotes megakaryocyte proliferation, polyploidization and, ultimately, the formation of increased numbers of platelets in the circulation. TPO has now been produced by recombinant technology and has entered clinical trials. This open label phase I study was designed to determine the safety, tolerance and pharmacokinetics of recombinant thrombopoietin (rhTPO) when administered to patients after undergoing high-dose chemotherapy followed by autologous bone marrow transplantation. rhTPO was administered intravenously by bolus injection at doses ranging from 0.3 to 4.8 microg/kg/day every 3 days to 30 patients and 0.6 microg/kg daily to three patients. rhTPO was begun the day after marrow infusion and continued until platelet recovery to >20,000/microl. G-CSF was concomitantly administered to promote myeloid recovery. Serious adverse events or neutralizing antibodies to rhTPO were not observed during the study. Median platelet recovery after ABMT was 19 days (range, 11-41). Neither the dose nor the schedule of rhTPO appeared to have any impact upon the time course of platelet recovery. In this phase I study, rhTPO was found to be well tolerated without the development of neutralizing antibodies and without compromising neutrophil recovery. Platelet recovery was similar for all doses studied warranting further evaluation in phase II and III trials designed to test for platelet recovery efficacy.

Acute bleeding and thrombocytopenia after bone marrow transplantation

The relationship between hemorrhage and low platelet count was first established in patients with acute leukemia, and has been widely applied to thrombocytopenic patients, including BMT patients. Yet, the role of thrombocytopenia in bleeding post BMT has not been systematically studied. We evaluated the risk of bleeding and outcome associated with thrombocytopenia in BMT patients who had prophylactic platelet transfusions at a trigger of 20 x 10(9)/l. Thrombocytopenia was investigated in 321 patients with moderate or severe bleeding (BLD), and in a matched comparison group of 287 patients who did not bleed (NBLD). Profound thrombocytopenia (< or = 10 x 10(9)/l) was found in 8.6% of the BLD patients during the week before the bleeding onset, significantly more frequent than in NBLD patients (2.1% to 4%, P < 0.02), during weeks 2 to 6 post BMT (the period when 75% of the bleeding initiated). On the first day of bleeding, platelet counts < or = 10 x 10(9)/l were found in 13.5%, 11-20 x 10(9)/l in 20.4%, and > 20 x 10(9)/l in 66.1% of all episodes. Overall survival in BLD patients was not associated with the severity of thrombocytopenia before bleeding onset. Severity of thrombocytopenia was significantly associated with reduced survival in NBLD patients. We concluded that bleeding post BMT was significantly associated with thrombocytopenia, but the attributable risk of bleeding from profound thrombocytopenia was not large. Thrombocytopenia may be an important clinical sign in NBLD patients, and should be further explored in relation to acute toxicities other than bleeding.

Standardized flow cytometric method for the accurate determination of platelet counts in patients with severe thrombocytopenia

BACKGROUND

The therapeutic option of prophylactic platelet (PLT) transfusion in cases of severe thrombocytopenia critically depends on the availability of accurate and precise counts because clinical decisions are widely based on decision or trigger points. Although often applied in current practice at a level of 20 Gpt/L, there is increasing evidence that the trigger points could safely be reduced to 10 or even 5 Gpt/L. In order to facilitate this downward revision, it is necessary to have PLT counting methods that are able to provide reliable results in the appropriate decision range.

METHODS

Postchemotherapy-induced pancytopenia PLT counting was performed in patients with hematological malignant disorders. This study describes a novel flow cytometric method that utilizes a PLT-specific monoclonal antibody (CD41a) in conjunction with fluorescent reference beads in order to derive absolute platelet numbers.

RESULTS

Applying a mathematical model, this flow cytometric method was shown to have a detection limit of 0.24 Gpt/L and a lower limit of quantification (coefficient of variation [CV] = 10%) of 1.1 Gpt/L. These values are a substantial improvement on previously reported results for the Technicon H1 automated instrument or manual hemocytometry. Moreover, although the flow cytometry and Technicon H3 methods were found by supplementary analyses to show a reasonably good correlation, the hematology instrument showed a distinct tendency to overestimate PLT counts at low levels.

CONCLUSION

It is proposed that this standardized immunoplatelet method offers the best approach in evaluating, at the clinical level, the possibility of lower PLT transfusion triggers. It can be used to evaluate the performance limitations of automated hematology analyzers that are widely used at the present time.

Platelet transfusions: utilization and associated costs in a tertiary care hospital

We implemented a prospective study to evaluate platelet transfusion utilization, resource use, and costs in a tertiary care hospital over a 6-month period. All hospitalized patients receiving platelet transfusions between July and December 1996 were followed prospectively to determine platelet use and costs. Clinical and financial data were collected, evaluated, and compared to identify trends in resource utilization based on admitting service and platelet-refractory status. One thousand nine hundred forty-four platelet units were transfused to 245 hospitalized patients (50.6% male, mean age 49 years) during the study period. The majority of platelet units transfused were single donor (N = 1,460, 75%) and administered to bone marrow patients and patients with a hematological malignancy/disorder. Median hospitalization costs per admission were $27,750, ranging from a high of $58,729 for admission to the Bone Marrow Transplant service to $13,856 per admission to the Internal Medicine/Other service. Patients were refractory to platelet transfusions during 21.6% of hospitalizations. Hospital stays were longer (35.0 days vs. 14.4 days, P < 0.001) and inpatient hospital costs ($103,956 vs. $37,817, P < 0.001) were more than two and a half times higher for patients refractory to platelet transfusions. Platelet utilization, resource use, and costs vary by admitting service. Refractoriness to platelet transfusion was associated with significantly greater costs and lengths of stay. Monitoring platelet transfusion practices, particularly for patients refractory to platelet transfusions, may be beneficial for limiting costs and improving efficacy.

Current and future trends in transfusion therapy

The increase in intensive treatment for cancer has impacted blood product transfusion practices. Transfusion guidelines are primarily institution specific, but the general concepts and theories are universal. Blood product screening has decreased the risk of transfusion-acquired infections; however, the risk is not obsolete. This article reviews current approaches to platelet, white blood cell, and red blood cell transfusions, as well as risks associated with these therapies (e.g., infection and transfusion-associated graft-versus-host disease). Pertinent laboratory studies, patient assessment, blood product administration, and patient education is discussed. The current approaches to platelet, white blood cell, and red blood cell transfusions are constantly changed and evaluated. Pediatric oncology nurses must stay up to date with these changes to provide optimal patient care.

Heparin-induced coagulopathy associated with staphylococcal protein A immunoadsorption treatment columns: an in vitro and in vivo analysis

BACKGROUND

The staphylococcal protein A (SPA) column used to treat refractory autoimmune and alloimmune thrombocytopenia and rheumatoid arthritis patients is primed with heparin to prevent possible fibrin clot formation when the patient's plasma is passed through the column. A BMT patient with refractory alloimmune thrombocytopenia had prolonged activated partial thromboplastin times (aPTTs) at the end of SPA column treatments. This observation led to in vivo and in vitro analysis of the kinetics of heparin elution from the SPA column.

STUDY DESIGN AND METHODS

Two patients with refractory rheumatoid arthritis, who were treated on five occasions with the SPA column (as a part of a national trial) primed with 5000 U of heparin, were monitored for aPTT and heparin in their plasma. In addition, two in vitro analyses were performed with FFP for heparin elution from the SPA column.

RESULTS

The in vivo studies showed the presence of 0.3 to 1.5 U per mL of heparin in patients' plasma at the end of the SPA column treatments that corresponded with the prolonged aPTTs. The in vitro studies showed that 82 to 85 percent heparin (approx. 4400 U) was eluted from the SPA column during rather than before the procedure.

CONCLUSION

Patients undergoing SPA column treatments, especially those with thrombocytopenia, may be at increased risk of bleeding as a result of the presence of a significant amount of heparin in their circulation during the entire period of SPA column treatment.

Current issues with platelet transfusion in patients with cancer

For the past 30 years, platelet transfusions have been used in the treatment of thrombocytopenia caused by decreased production, inadequate function, or increased destruction of platelets. The number of platelet transfusions has increased more than transfusions of other blood components, shifting from whole blood use for the platelet source to plateletpheresis. Hematology/oncology patients are among the largest group receiving platelet transfusions, primarily because the more aggressive chemotherapies produce more acute and prolonged thrombocytopenia. While platelet transfusions often rescue patients with very low platelet levels, they are associated with the risk of viral and bacterial infections, as well as alloimmunization. Platelet donor recruitment can also be difficult, and platelet transfusion can be very expensive depending on the source of platelets. As a result, prophylactic transfusions are less likely to be administered at higher platelet counts, reducing platelet use and cost of platelet transfusions. However, cancer patients receiving intensive chemotherapy or myeloablative regimens require multiple platelet transfusions. For these patients, alternate strategies are needed so that platelet transfusions can be significantly reduced or eliminated.

Thrombopoietin in the treatment of acute myeloid leukemia and in stem-cell transplantation

Recent studies indicate that thrombopoietin (TPO) may be highly effective in mobilizing autologous peripheral blood stem cells (PBSCs) for transplantation in patients undergoing intensive chemotherapy. The yield of CD34+ progenitor cells can be increased as can the percentage of patients achieving adequate grafts for use in transplantation. However, the effect of TPO in patients with hematologic malignancies undergoing induction or postremission chemotherapy or in the stem-cell transplantation setting has not been demonstrated. Further study is warranted for better definition of the role of TPO in the treatment of severe thrombocytopenia in these settings.

Immunoplatelet counting: a proposed new reference procedure

Given the high degree of interoperator error and poor precision of manual platelet counting, it has recently been proposed that an immunoplatelet counting method could become the new reference procedure. Platelets are identified immunologically with a suitable monoclonal antibody, and the platelet count is derived from the ratio of fluorescent platelet events to collected red blood cell (RBC) events that are also counted by a reliable and calibrated standard impedance counter (RBC ratio). In this study, we have set up a rapid and simple method for immunoplatelet counting and simultaneously compared the RBC ratio with the bead ratio derived from two different preparations of commercial calibration beads (Trucount and FlowCount beads). Comparison of the level of imprecision of the RBC ratio with either the manual count or bead ratios revealed a superior coefficient of variation of < 5% even in samples with a platelet count < 20 x 10(9)/l. The RBC ratio correlated extremely well with the existing manual phase reference method (r2 = 0.93) and especially well with three different commercial impedance counters and a dual-angle optical counter (r2 = 0.98-0.99). However, at < 100 x 10(9)/l, the correlation of the RBC ratio with the dual-angle optical count (ADVIA 120) (r2 = 0.96) was superior to all impedance counters. This suggests that automated optical counting methods may be more accurate at determining platelet counts in thrombocytopenic samples. As the RBC ratio is rapid, cheap and relatively easy to perform, we propose that this method could replace the manual count as a new international reference method.

A Randomized, Double-Blind, Placebo-Controlled Study With Pegylated Recombinant Human Megakaryocyte Growth and Development Factor (PEG-rHuMGDF) as an Adjunct to Chemotherapy for Adults With De Novo Acute Myeloid Leukemia

To determine the safety, biologic, and clinical benefits of pegylated recombinant human megakaryocyte growth and development factor (PEG-rHuMGDF; Amgen, Thousand Oaks, CA) after myelosuppressive chemotherapy in acute myeloid leukemia (AML), 108 adult patients with de novo AML were randomized to receive either PEG-rHuMGDF (2.5 μg/kg/d or 5 μg/kg/d) for up to 21 doses (group A), a single dose of 2.5 μg/kg PEG-rHuMGDF, 7 daily doses of 2.5 μg/kg PEG-rHuMGDF (group B), or placebo. The greatest biologic activity was seen in group A with a median peak platelet count of 1,084 × 109/L, occurring at a median 9 days after the last dose of study drug, compared with 517 × 109/L and 390 × 109/L in group B and placebo group, respectively. Thrombocytosis (platelets &gt;1,000 × 109/L) was seen at rates of 52%, 8%, and 9% in groups A, B, and placebo, respectively, but were not associated with any adverse event. There was no effect on median time to transfusion independent platelet recovery (≥20 × 109/L). The median time to neutrophil recovery (≥500/μL) and red blood cell transfusion requirements were similar in all groups, and there was no apparent stimulation of leukemia. PEG-rHuMGDF was biologically active and well tolerated. Further investigation of dose and scheduling is required, specifically earlier dosing before and during chemotherapy.

A Randomized, Double-Blind, Placebo-Controlled Study With Pegylated Recombinant Human Megakaryocyte Growth and Development Factor (PEG-rHuMGDF) as an Adjunct to Chemotherapy for Adults With De Novo Acute Myeloid Leukemia

To determine the safety, biologic, and clinical benefits of pegylated recombinant human megakaryocyte growth and development factor (PEG-rHuMGDF; Amgen, Thousand Oaks, CA) after myelosuppressive chemotherapy in acute myeloid leukemia (AML), 108 adult patients with de novo AML were randomized to receive either PEG-rHuMGDF (2.5 μg/kg/d or 5 μg/kg/d) for up to 21 doses (group A), a single dose of 2.5 μg/kg PEG-rHuMGDF, 7 daily doses of 2.5 μg/kg PEG-rHuMGDF (group B), or placebo. The greatest biologic activity was seen in group A with a median peak platelet count of 1,084 × 109/L, occurring at a median 9 days after the last dose of study drug, compared with 517 × 109/L and 390 × 109/L in group B and placebo group, respectively. Thrombocytosis (platelets >1,000 × 109/L) was seen at rates of 52%, 8%, and 9% in groups A, B, and placebo, respectively, but were not associated with any adverse event. There was no effect on median time to transfusion independent platelet recovery (≥20 × 109/L). The median time to neutrophil recovery (≥500/μL) and red blood cell transfusion requirements were similar in all groups, and there was no apparent stimulation of leukemia. PEG-rHuMGDF was biologically active and well tolerated. Further investigation of dose and scheduling is required, specifically earlier dosing before and during chemotherapy.

Optimal dosing and triggers for prophylactic use of platelet transfusions

Despite the reliance on platelet transfusion support in patients receiving myeloablative therapy, controversies surround platelet transfusion practices. These include the appropriate platelet dose and the threshold at which prophylactic platelet transfusions will be most effective. These issues bear directly on patient outcome (donor exposure and bleeding complications), cost effectiveness of transfusion, and maintenance of adequate platelet inventories. This review examines the recent studies that have taken on the task of resolving these questions in order to provide optimal platelet transfusion guidelines. Studies now have convincingly demonstrated that a 10,000/microL threshold for prophylactic platelet transfusion is safe and effective in uncomplicated thrombocytopenic patients. Although platelet dosages vary, in general, smaller doses are both effective and inventory-sparing in the more complicated inpatient setting, while larger platelet doses allow for an increased transfusion interval for chronic outpatient support.

The role of transfusion medicine physicians. A vanishing breed?

Physicians with interest or expertise in transfusion medicine must apply their clinical consultation and laboratory management skills to be accorded support for their activities. To establish credibility, efforts must initially be directed where patient benefit and financial gain can be documented. Focusing efforts on practice improvements and sharing the results of those efforts with physician colleagues and administrators can help ensure continued support. Transfusion medicine continues to play an important role in health care, particularly in an era of managed care and reduced resources. Investment in the activities of this discipline will pay off for patients, clinicians, and hospitals.

How to improve transfusion medicine. A treating physician's perspective

As transfusion medicine becomes more complex, cooperative strategies are gaining increasing importance in relaying information to the treating physician and in incorporating the treating physician into the education and quality control processes. The broad domain of transfusion medicine is illustrated by the variety of disciplines involved in defining the use of products such as fresh frozen plasma and the newly released solvent-detergent-treated plasma, fibrin glue and highly purified fibrin sealant, and leukoreduced and irradiated blood products. Cooperative efforts among physicians and other personnel of multiple disciplines are essential to ensure appropriate use and continuous evaluation of blood products.

Risks, costs, and alternatives to platelet transfusions

The use of platelet transfusions has increased greatly in the past decade and is likely to continue to escalate because of the risks of thrombocytopenia in patients receiving dose-intensive cancer chemotherapy, the increased use of hematopoietic progenitor cell transplantation, and the prevalence of human immunodeficiency virus infection. Despite marked advances in procedures for ensuring the safety of platelets, including intensive donor screening, infectious disease marker testing, and increased use of leukodepletion techniques, platelet transfusions carry a significant risk for immunologic disorders and transmission of bacterial, viral, and perhaps other diseases and can entail a very high cost. In addition, thrombocytopenia has the potential to interfere with delivery of chemotherapy on schedule and at the planned doses, thus potentially compromising treatment outcome. The limitations of platelet transfusions have prompted the development of agents with the potential to stimulate platelet production and thus reduce or eliminate the need for transfusions. Two such agents, interleukin-11 (IL-11) and thrombopoietin (TPO), have demonstrated promise in clinical trials. In November, 1997, IL-11 received FDA approval for the prevention of severe thrombocytopenia in high risk patients receiving myelosuppressive chemotherapy. Thrombopoietic growth factors have the potential to greatly simplify and increase the safety of transfusion medicine.

A Restrictive Platelet Transfusion Policy Allowing Long-Term Support of Outpatients With Severe Aplastic Anemia

The threshold for prophylactic platelet transfusions in patients with hypoplastic thrombopenia generally recommended in the standard literature is 20,000 platelets/μL. A more restrictive transfusion policy may be indicated in patients with chronic severe aplastic anemia (SAA) in need of long-term platelet support. We evaluated the feasibility and safety of a policy with low thresholds for prophylactic transfusions (≤5,000 platelets/μL in stable patients; 6,000 to 10,000 platelets/μL in cases with fever and/or hemorrhagic signs) combined with progressive lengthening of transfusion intervals (up to at least 7 days irrespective of the interim course of platelet counts). The study was based on a retrospective analysis of a total of 18,706 patient days with platelet counts ≤10,000/μL in patients with chronic SAA treated (for more than 3 months) on an outpatient basis. Altogether, 1,135 platelet transfusions were given, 88% at counts ≤10,000/μL and 57% at counts ≤5,000/μL. The mean transfusion interval was 10 days. During the period of observation, three major nonlethal bleeding complications occurred, which could be well controlled. We conclude that the restrictive policy with low transfusion thresholds and prolonged transfusion intervals proved feasible and safe in chronic SAA patients.

A Restrictive Platelet Transfusion Policy Allowing Long-Term Support of Outpatients With Severe Aplastic Anemia

The threshold for prophylactic platelet transfusions in patients with hypoplastic thrombopenia generally recommended in the standard literature is 20,000 platelets/μL. A more restrictive transfusion policy may be indicated in patients with chronic severe aplastic anemia (SAA) in need of long-term platelet support. We evaluated the feasibility and safety of a policy with low thresholds for prophylactic transfusions (≤5,000 platelets/μL in stable patients; 6,000 to 10,000 platelets/μL in cases with fever and/or hemorrhagic signs) combined with progressive lengthening of transfusion intervals (up to at least 7 days irrespective of the interim course of platelet counts). The study was based on a retrospective analysis of a total of 18,706 patient days with platelet counts ≤10,000/μL in patients with chronic SAA treated (for more than 3 months) on an outpatient basis. Altogether, 1,135 platelet transfusions were given, 88% at counts ≤10,000/μL and 57% at counts ≤5,000/μL. The mean transfusion interval was 10 days. During the period of observation, three major nonlethal bleeding complications occurred, which could be well controlled. We conclude that the restrictive policy with low transfusion thresholds and prolonged transfusion intervals proved feasible and safe in chronic SAA patients.