TRANSFUSION PRACTICE Utilization of cross-matched or HLA-matched platelets for patients refractory to platelet transfusion Benjamin Rioux-Massé,1 Claudia Cohn,2 Bruce Lindgren,3 Shelly Pulkrabek,2 and Jeffrey McCullough2
BACKGROUND: Use of cross matching or HLA matching for donor selection is the basis of managing patients refractory to platelet (PLT) transfusion. Because of changes in patient care, we evaluated the effect of cross matching and HLA matching in patients refractory to PLT transfusion. STUDY DESIGN AND METHODS: We identified all patients who received either HLA-matched or crossmatched PLTs during a 3-year period at our medical center. Patient records were reviewed and laboratory data were collected. One- to 4-hour corrected count increments (CCIs) were calculated for transfusions given up to 72 hours before receiving these specialized units and the HLA-matched or cross-matched units themselves. RESULTS: Thirty-two patients were identified who received a total of 354 PLT transfusions. Of these, 161 were from unselected apheresis, 152 were cross matched, and 41 were HLA selected. The median CCI for random-donor transfusions was 0 (range, 0 × 10910.5 × 109/L), for cross-matched PLT transfusions 1.7 × 109/L (0 × 109-5.1 × 109/L), and for HLA-matched transfusions 1.2 × 109/L (0 × 109-13.9 × 109/L). Only 25 and 30% of cross-match–compatible or HLA-selected units, respectively, gave 1- to 4-hour CCIs of more than 5.0 × 109/L compared to 12% of the transfusions from random donors. There were no significant differences in the 1- to 4-hour CCIs when comparing random units with HLA-selected or cross-match–compatible units. There was also no significant difference when comparing the HLA-matched and cross-match–compatible PLT units with each other. CONCLUSIONS: The use of cross-match–compatible or HLA-matched units did not provide better increments in PLT count when compared to random nonselected units. Clinical factors may overpower immunologic matching.
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P
oor response or refractoriness is a complication of platelet (PLT) transfusion therapy that can have a significant impact on PLT utilization and clinical outcome.1-12 Both immune and nonimmune factors contribute to PLT consumption and cause a PLT-refractory state.9-16 Immune refractoriness is caused mainly by HLA Class I antibodies.12,15,17-22 Algorithms have been developed to help determine etiology and management of PLT refractoriness.23-25 As the role of HLA antibodies was delineated, methods to select donors using HLA matching were developed18-21 and large pools of HLA-typed PLT donors were established by blood centers.21,26 Subsequently, alloimmunization and PLT refractoriness were linked to white blood cells present in transfused components22,27,28 and a large definitive study showed that leukoreduction could reduce the development of alloimmunization and development of PLT refractoriness.22 This led to the increased use of leukoreduced blood products. As methods for PLT antibody detection were enhanced, a cross-match procedure began to be used for PLT selection instead of using HLA-typed donors.29-36 Studies indicated that HLA and cross-matching are equally effective for selecting compatible units to overcome immunemediated refractoriness.37
ABBREVIATION: PRA = panel-reactive antigen. From the 1Centré Hospitalier de l’Université de Montréal, Montréal, Québec, Canada; and the 2Department of Laboratory Medicine & Pathology and 3Biostatistics and Bioinformatics Core, Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota. Address reprint requests to: Jeffrey McCullough, Department of Laboratory Medicine & Pathology, University of Minnesota, 420 Delaware Street SE, Minneapolis, MN 55455; e-mail: [email protected]. Received for publication January 14, 2014; revision received April 17, 2014, and accepted April 21, 2014. doi: 10.1111/trf.12739 © 2014 AABB TRANSFUSION 2014;54:3080-3087.
CROSS-MATCHED OR HLA-MATCHED PLT TRANSFUSION
While the immune factors that create a PLT-refractory state can be overcome with HLA or cross-matched units, patients may also have multiple clinical factors that cause accelerated PLT consumption. Distinguishing these immune and nonimmune factors can be difficult to impossible in complicated patients. The corrected count increment (CCI), which is used to determine an adequate response to PLT transfusions,38 does not identify the cause of refractoriness or distinguish between immune and nonimmune factors. While there is a generalized belief that a 1-hour CCI indicates an alloimmune cause for refractoriness, the evidence to back this idea is highly variable.12-15,38 Thus, a low CCI could be due to alloimmune factors or clinical factors in the patient that increase PLT consumption. During the past 20 years, treatment-related mortality after aggressive chemotherapy and hematopoietic stem cell transplantation has improved. However, some patients experience longer periods of aplasia with a resultant increase in blood utilization.39 The consequence may be a higher prevalence and burden of nonimmune PLT consumption factors. These changes may also change the clinical value of HLA-typed or cross-matched PLTs. Since selected or matched products are more costly than standard PLT units, it is important to review their current effectiveness and develop algorithms for their use. We report a 3-year retrospective analysis of patients with PLT refractoriness and response to transfusion of random, cross-match–compatible, and HLA-matched PLT units during the initial hospitalization in which PLT refractoriness occurred.
MATERIALS AND METHODS Patients We conducted a retrospective analysis of all blood bank records at the University of Minnesota Medical Center and identified 56 patients who received either cross-matched or HLA-matched PLT products during that time. Four were excluded because of restricted patient record access. Patients were included in the analysis only if an inpatient hospitalized for chemotherapy or bone marrow transplantation (BMT) weighed more than 10 kg (limit for utilization of half dose of apheresis PLT units at our institution), had a confirmed-positive immune-mediated PLT refractoriness work-up, and received transfusion with crossmatched and/or HLA-matched PLT units during that hospitalization. Thirty-two patients fulfilled these criteria and are the basis of this report. The study was approved by the local institutional review board. A positive immune PLT-refractory work-up was initiated when a patient had a posttransfusion CCI of less than 5.0 × 109/L on two or more usually consecutive occasions. The work-up was considered to be positive either with a PLT cross-match test result showing incompatibility with at least 1 unit
tested or an HLA antibody screen detecting the presence of an HLA Class I antibody against any number of antigens in a single-well test system. While tests were also performed for PLT-specific antibodies, these results were not used to define a positive immune PLT-refractory condition.
Data collection The analysis of the initial episode of PLT transfusion refractoriness was conducted for each patient. For each patient the following data were recorded for the defined hospitalization episode: age; sex; body surface area; diagnostic treatment category (chemotherapy or BMT); HLA typing (Class I); initial PLT cross-match incompatibility result, HLA Class I antibody screen, and human PLT antigen (HPA) antibody screen results; WHO Grade 3 to 4 bleeding episodes; deaths; 1- to 4-hour CCIs; and 4- to 24-hour CCIs. The CCIs included for analysis in this study are limited to the period beginning 72 hours before the first cross-matched or HLA-matched unit up to 72 hours after the last cross-matched or HLA-matched transfusion. The WHO bleeding grade of 3 or 41,2,11 was determined by study personnel during review of the medical record for the period described above.
PLT transfusion refractoriness evaluation The cross-match incompatibility screen, HLA Class I antibody screen, and HPA antibody screen were performed by the American Red Cross, Mid-America Blood Services Division. The cross-match incompatibility screen test is performed with a solid phase system for the detection of IgG antibodies to PLTs (CAPTURE-P, Immucor, Inc., Norcross, GA). The HLA Class I antibody screen and the HPA antibody screen are performed with an assay (PAKPLUS, Gen-Probe GTI Diagnostics, Inc., Waukesha, WI). The definition of immune PLT refractoriness was a positive cross-match for one or more PLT units or a positive HLA antibody test against at least one screening cell.
PLT products supply PLT products (random, cross-match–compatible, and HLA-matched units) were supplied by the American Red Cross, Mid-America Blood Services Division. All PLTs in this study were collected by apheresis. Those designated “random” were selected only based on ABO and Rh type. HLA-matched units were group A, B1U, or B1X match only.20 Cross-reactive groups were considered only in selecting HLA for B1X matches. HLA-matched units were not all tested by cross-match incompatibility. Thus, it is not known whether those units would have been compatible in the cross-match. The HLA antibody avoidance Volume 54, December 2014 TRANSFUSION
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technique was not used because the supplier database does not support this.
CCI calculation CCI calculations for all PLT transfusions were performed according to a previously published formula.1,2,11,12,22 Since the exact PLT content of each unit was not known, a PLT dose of 4 × 1011/L was used for CCI calculation for all units. PLT transfusions without a valid pre- or postcount and a reliable time of transfusion were excluded from analysis. When multiple units were transfused in a short period of time with no intervening PLT count, they had to be excluded from analysis, independently of the overall response to the multiple PLT transfusions. For some parts of this analysis, a 1- to 4-hour CCI of more than 5.0 × 109/L was considered to be a successful transfusion.
TABLE 1. Patient characteristics Number of patients Sex (male/female) Age (years), median (range) Diagnosis Acute myeloid leukemia Others* Treatment category Chemotherapy Transplant†
32 12/20 39.5 (9-67) 14 18 10 22
* Others: dyskeratosis congenita (3), acute lymphoblastic leukemia (2), myelodysplastic syndrome (2), ovarian carcinoma (2), breast carcinoma (1), chronic lymphocytic leukemia (1), thalassemia (1), non-Hodgkin’s lymphoma (1), Hodgkin’s lymphoma (1), multiple myeloma (1), Fanconi anemia (1), dystrophic epidermolysis bullosa (1), and cerebral adrenoleukodystrophy (1). † Transplant: 21 allogeneic transplants and one autologous transplant.
Statistical analysis The number of successful transfusions per patient, as determined by a CCI of more than 5.0 × 109/L (1-4 hr, 4-24 hr), was modeled as a Poisson variable. We compared the average success rate between the three types of PLT transfusions (random, cross-match–compatible, and HLA-matched units). Since some patients received both cross-matched and HLA-matched units, a generalized estimating equation model was used, which allows for repeated observations on the same patient. In this study most patients received more than one type of transfusion. The covariance structure between the repeated transfusion types was specified as unstructured for the majority of analyses. In one case where the data were very sparse, the independent variance and covariance structure was utilized. The comparisons between the three types of PLT transfusions were performed pairwise. The analysis assumes that the order in which the patient received the different types of transfusions was unrelated to whether or not the transfusion was successful.
RESULTS There were 32 patients in the study, most of whom had undergone a hematopoietic stem cell transplantation (Table 1). All patients were tested for HLA antibodies, PLTspecific antibodies, and also for cross-match incompatibility (Table 2). Nine had PLT-specific antibodies. During the period of study, the patients received a total of 354 transfusions for which pretransfusion and 1- to 4-hourposttransfusion PLT counts were available (Table 3). A total of 161 of 354 (45%) were random-donor units, 152 (42%) were selected by cross-match, and 41 (13%) were HLA matched (Table 3). The transfusions with randomdonor units were all given within 72 hours before the first use of HLA- or cross-matched units. As expected, the 1- to 4-hour CCIs from the random-donor units were low, with 3082
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TABLE 2. Type of selected PLT products provided to patients in this study Type of PLT product HLA selected Cross match selected HLA and cross match Total
Number of patients 11 10 11 32
a median of 0 (zero), and a range of 0 × 109 to 10.5 × 109/L. Cross-match–compatible units gave a median 1- to 4-hour CCI of 1.7 × 109/L and the HLA-matched transfusions gave a median 1- to 4-hour CCI of 1.2 × 109/L. While some transfusions resulted in higher CCIs (10.5 × 109, 15.1 × 109, and 13.9 × 109/L) the change in PLT count after most transfusions was small. One transfusion of a B1X match resulted in a CCI of 13.9 × 109/L while other transfusions to this patient had CCIs of zero. We arbitrarily selected a CCI of 5.0 × 109/L as representing a satisfactory response to transfusion.22 As expected, only 12% of random-donor units gave this response. While cross-matched and HLA-matched transfusions gave a higher response rate, this was disappointingly low at 25 and 29%, respectively (Table 4). Thus, as expected, most random-donor transfusions (88%) gave poor responses, but surprisingly 75 and 71% of crossmatched and HLA-selected units also gave poor responses (Table 4). The generalized estimating equation model takes into account that the same patient may have received more than one type of transfusion when comparing the average number of successful transfusions per patient for random versus cross-match compatible, random versus HLA, and cross-match compatible versus HLA (Tables 5, 6, and 7). A successful transfusion was defined as a 1- to 4-hour or 4to 24-hour CCI of more than 5 × 109/L. While the crossmatch was 2.06 times more likely than random-donor
CROSS-MATCHED OR HLA-MATCHED PLT TRANSFUSION
TABLE 3. Evaluation of CCIs between random, cross-match–compatible, and HLA-matched PLT transfusion* Selection method
Number of units
Random Cross match HLA match Total
161 152 41 354
1- to 4-hr CCI (×109/L) Median Range 0 1.7 1.2
Number of units
0-10.5 0-15.0 0-13.9
109 60 7 176
4- to 24-hr CCI (×109/L) Median Range 0 0 3.3
0-11.6 0-14.3 1.4-8.7
* CCI calculations are limited to the period up to 72 hours before the use of the first cross-matched and HLA-matched PLT unit to 72 hours after the last cross-matched and HLA-matched PLT unit.
TABLE 4. Response to transfusion using a CCI of 5.0 × 109/L as a satisfactory response 1- to 4-hr CCI > 5.0 (×109/L) Selection methods Random Cross match HLA match
Number of units
Number
%
161 152 41
19 38 12
12 25 29
4- to 24-hr CCI > 5.0 (×109/L) Number of units Number 109 60 7
%
7 11 3
6 18 43
TABLE 5. Average number of successful PLT transfusions (CCI > 5.0 × 109/L) per patient between cross-match–compatible and random units (n = 30 patients) CCI 1 to 4 hr (n = 52) 4 to 24 hr (n = 45)
Successful cross-match compatible (C) transfusions per patient 0.25 0.19
Successful random (R) transfusions per patient 0.12 0.06
Ratio (95% CI) of average number of successful transfusions (C/R) 2.06 (1.20-3.53) 2.97 (1.23-7.21)
p value 0.057 0.110
TABLE 6. Average number of successful PLT transfusions (CCI > 5.0 × 109/L) per patient between HLA-matched and random units (n = 29 patients) CCI 1 to 4 hr (n = 35) 4 to 24 hr (n = 28)
Successful HLA match (H) transfusions per patient 0.30 0.44
Successful random (R) transfusions per patient 0.12 0.06
Ratio (95% CI) of average number of successful transfusions (H/R) 2.47 (1.24-4.92) 6.86 (3.47-13.57)
p value 0.110 0.283
TABLE 7. Average number of successful PLT transfusions (CCI > 5.0 × 109/L) per patient between HLA-matched and cross-match–compatible units (n = 31 patients) CCI 1 to 4 hr (n = 39) 4 to 24 hr (n = 25)
Successful HLA match (H) transfusions per patient 0.32 0.43
Successful cross-match compatible (C) transfusions per patient 0.24 0.18
PLTs to provide a successful 1- to 4-hour result and 2.97 times more likely to provide a successful 4- to 24-hour result, the average number of successful transfusions was still low, being 0.25 for cross-matched compared to 0.12 for random-donor units (Table 5). These frequencies of successful transfusion were not different from randomdonor units, although this was a small study and may not have had adequate power. For random-donor units compared to HLA selected, the HLA-selected units were 2.47 and 6.86 times more likely to give a successful transfusion at 1 to 4 and 4 to 24 hours posttransplant, respectively (Table 6). However, this difference in this small study was
Ratio (95% CI) of average number of successful transfusions (H/C) 1.33 (0.65-2.73) 2.34 (0.68-8.08)
p value 0.564 0.266
not significant and the average number of 1- to 4-hour successful transfusions was still very low at 0.3 for HLAselected compared to 0.12 for random-donor units and 4to 24-hour transfusions 0.44 for HLA and 0.06 for random units (Table 6). When HLA-selected units were compared with cross-matched units, the HLA-selected units were 1.33 and 2.34 times more likely to give a successful 1- to 4and 4- to 24-hour transfusion (Table 7). To better understand the relative effectiveness of HLA compared to cross-matched PLT units, we examined the proportion of cross-match incompatibility against the presence of HLA antibodies. When no HLA antibodies Volume 54, December 2014 TRANSFUSION
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TABLE 8. Relationship between proportion of positive cross-matched units and HLA antibody screen HLA antibody Negative (n = 10) Positive
50% cross-matched units incompatibility 3/10
3/11
8/11†
* Number of incompatible PLT products: 1/14, 4/14, 7/14, 3/13, 2/14, 2/14, and 1/14. † Number of incompatible PLT products: 11/14, 11/14, 8/8, 14/14, 11/14, 9/14, 9/12, and 12/14.
were found in the screening test, seven of 10 patients had less than 50% cross-match–incompatible units (Table 8). Conversely, when the HLA antibody test was positive, eight of 11 patients had cross-match–incompatible rates of more than 50%. Thus, when HLA antibodies were present, there was a higher likelihood of finding crossmatch–incompatible units. Since we used a screening test for HLA antibodies, we cannot correlate the strength of the HLA antibodies, in terms of the panel-reactive antigen (PRA) with the cross-match assay. It has been reported that a PRA greater than 20% suggests PLT refractoriness;40 however, to our knowledge, data adjusting the PRA with additional information about antibody strength (mean fluorescent intensity) is currently lacking. It is also interesting to note that the detection of PLT-specific antibodies on the screening test did not correlate with refractoriness (data not shown). While it has been reported that PLT specific antibodies (HPA) can cause refractoriness,41 our limited data are not adequate to determine whether HPA antibodies are an important cause of refractoriness. In refractory patients, the value of HLA matching outweighs the detriment of ABO mismatching.20 In this study, PLTs were either ABO identical or compatible with the patient—none were incompatible containing ABO antigens to which the patients had antibodies. Since the purpose of PLT transfusions is control or prevention of bleeding, we determined the rate of WHOgraded bleeding in these patients. Despite the lack of response to PLT transfusion, only six of the 32 patients experienced WHO Grade 3 or 4 bleeding (Table 9). Five of these were hemorrhagic cystitis and one involved pulmonary hemorrhage. There were seven deaths in these 32 patients, two of which were considered by the attending physicians to be related to hemorrhage. One involved hemorrhagic cystitis and one pulmonary hemorrhage.
DISCUSSION In this study, only 25 and 29% of transfusions of crossmatched or HLA-matched PLTs provided a CCI that was considered to represent a successful transfusion. While this is better than the 12% successful random-donor 3084
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TABLE 9. Bleeding outcomes in the 32 PLT-refractory patients Outcome WHO Grade 3-4 bleeding Hemorrhagic cystitis Pulmonary hemorrhage Deaths Hemorrhagic deaths Hemorrhagic cystitis Pulmonary hemorrhage
Number 6 5 1 7 2 1 1
Percent 19
22 6
transfusions, the effectiveness of HLA- or cross-matched PLT transfusions in these patients was of limited value. However, to some extent this might not be surprising. Some PLT refractory patients with no complicating factors do not have HLA antibodies.12,15 Conversely, most patients with HLA antibodies9,22,23,35 have a poor response to transfusion, although some do have a satisfactory response.22,40,41 In original studies of HLA matching for refractory patients by Duquesnoy and colleagues,20 they showed similar responses to transfusion for different degrees of mismatch. This led to the development of files of HLA-typed donors and the implementation of HLA matching as one of the strategies for managing patents refractory to PLT transfusion. However, in those studies the range of responses for different HLA matches was similar.20 Thus, many transfusions of well-matched units gave a poor response and many poorly matched transfusions gave a good response. Overall, 20% to 50% of HLAmatched transfusions did not give a good response.19,20 The data did not allow comparison of the number of “good” responses to poor responses in individual patients since the point was to demonstrate that some mismatching could give effective transfusions. Data from others37,42 showed similar results and so failure of many wellmatched donor units is not unexpected. All of the HLAselected units in our study were A, B1U, or B1X match grade so we could have expected satisfactory mean responses from those transfusions. Pavenski and coworkers43 summarized 30 reports of the effect of HLA-matched PLT transfusions and concluded that “use of HLA matched leukoreduced PLTs was associated with a higher increment . . . compared to random-donor leukoreduced PLTs.” However, most of the studies covered in this report are from the 1970 to 1990 era and the current clinical situations may differ from those at the time covered by Pavenski and colleagues.43 As PLT antibody techniques were refined and the failure rate of up to 50% of HLA-matched transfusions was recognized, interest developed in PLT cross matching. The positive predictive value of various PLT cross-match techniques ranged from 73% to 100% and the negative predictive value from 52% to 92%.44 However, many of these studies were retrospective and some of the prospective studies did not even use fresh PLTs for cross-match
CROSS-MATCHED OR HLA-MATCHED PLT TRANSFUSION
testing. A solid-phase red blood cell (RBC) adherence assay which is now in widespread use (although periodically unavailable) originally predicted a successful transfusion outcome in 97% of patients with no clinical factors that might cause nonimmune PLT destruction34,35 and other studies36 suggested that the solid phase RBC adherence assay was superior to HLA matching, but from the aggregate experience, it is not unexpected that some transfusions that are compatible in a PLT cross-match do not give a good response. PLT-specific antibodies are not usually related to poor response to transfusions,15,22,44 but our data were not adequate to determine this. In this study, we used HLA matching but not the HLA avoidance technique in which the antigen corresponding to known HLA antibody specificities is avoided.45,46 It is possible that this could have given better responses compared with the HLA matching technique, although Petz and colleagues46 found similar results of HLA matching and the HLA antigen avoidance method. There are several limitations to our study. The number of patients and number of HLA-matched transfusions were small. Patients were not randomized to receive either HLA- or cross-matched PLTs. Cross-matched PLTs were usually used first because they were readily available whereas HLA-matched donors needed to be contacted and scheduled for donation. Even small increases in PLT count or low numbers of circulating PLTs can be effective in providing hemostasis,1 so it is possible that the HLA or cross-match transfusions were clinically effective. Hematology, oncology, and stem cell transplantation have evolved considerably since the early work on HLA selection and even the work on PLT cross-matching. Chemotherapy is more aggressive resulting in greater toxicity, stem cell transplants are more widely used with different stem cell sources especially cord blood and performed in older patients or those at higher risk. Patients are more complicated and thus may have the presence of more factors known to interfere with successful PLT transfusion. For instance, sepsis, fever, graft-versus-host disease, bleeding, antibiotics, and amphotericin therapy are established factors that reduce the transfusion response.9,12-16 The source of stem cells for transplant affects the duration to engraftment and thus cord blood transplant patients use considerably more products.39 Although we did not study this, it seems likely that these complicating factors may have overpowered the value of HLA and cross matching. A poor response to PLT transfusion often occurs in very complex patients and in one study, 80% of patients who died were refractory to PLT transfusion.47 It has been estimated that a substantial proportion of refractory patients are due to nonimmune (clinical) factors.5,9,10,13,14,16,48 This portion may be even higher presently, thus further reducing the value of specially matched PLTs. Another possible reason for a greater impact of nonimmune factors is that the widespread use of
leukoreduction has reduced the likelihood of alloimmunization, thus resulting in a higher proportion of PLT refractoriness being due to nonimmune factors. Thus, in conclusion, it is possible that the evolution in patient care especially of stem cell transplantation has led to more complicated patients with more clinical factors that have impact on the PLT posttransfusion increment. Such patients cannot be managed by immunologic matching. Immunologic matching for PLT-refractory patients may no longer be of value in many patients, although our study is small and a larger prospective randomized controlled trial is warranted. Therefore, we recommend that either or both HLA matching and cross matching be attempted for two transfusions and, if unsuccessful, regular randomdonor units be used. This approach is also consistent with recent observations that a low dose of PLTs is equally effective as the current standard dose in controlling or preventing bleeding and that bleeding is no more likely at PLT counts between 5.0 × 109 and 80.0 × 109/L.1 CONFLICT OF INTEREST The authors have disclosed no conflicts of interest.
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41.
42.
in predicting the need for HLA-matched preparations. JAMA 1980;243:435-8. Solh M, Brunstein C, Morgan S, et al. Platelet and red blood cell utilization and transfusion independence in umbilical cord blood and allogeneic peripheral blood hematopoietic cell transplants. Biol Blood Marrow Transplant 2011;17:710-6. Hogge DE, Dutcher JP, Aisner J, et al. Lymphocytic antibody is a predictor of response to random donor platlet transfuison. Am J Hematol 1983;14:363-9. Pappalardo PA, Secord AR, Quitevis P, et al. Platelet transfusion refractoriness associated with HPA-1a (PI(A1)) alloantibody without coexistent HLA antibodies successfully treated with antigen-negative platelet transfusions. Transfusion 2001;41:984-7. Grumet FC, Yankee RA. Long-term platelet support of patients with aplastic anemia-effect of splenectomy and steroid therapy. Ann Intern Med 1970;73:1-7.
CROSS-MATCHED OR HLA-MATCHED PLT TRANSFUSION
43. Pavenski K, Rebulla P, Duquesnoy R, et al. Efficacy of HLAmatched platelet transfusions for patients with hypoproliferative thrombocytopenia: a systematic review. Transfusion 2013;53:2230-42. 44. Heal JM, Blumberg N, Masel D. An evaluation of crossmatching, HLA, and ABO matching for platelet transfusions to refractory patients. Blood 1987;70:23-30. 45. Nambiar A, Duquesnoy RJ, Adams S, et al. HLAMatchmaker-driven analysis of responses to HLAtyped platelet transfusions in alloimmunized thrombocy-
46. Petz LD, Garratty G, Calhoun L, et al. Selecting donors of platelets for refactory patients on the basis of HLA antibody specificity. Transfusion 2000;40:1446-56. 47. Jones RJ, Lee KS, Beschorner WE, et al. Venoocclusive disease of the liver following bone marrow transplantation. Transplantation 1987;44:778-83. 48. Legler TJ, Fischer I, Kittmann J, et al. Frequency and causes of refractoriness in multiply transfused patients. Ann Hematol 1997;74:185-9.
topenic patients. Blood 2006;107:1680-7.
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BACKGROUND: Use of cross matching or HLA matching for donor selection is the basis of managing patients refractory to platelet (PLT) transfusion. Because of changes in patient care, we evaluated the effect of cross matching and HLA matching in patients refractory to PLT transfusion. STUDY DESIGN AND METHODS: We identified all patients who received either HLA-matched or crossmatched PLTs during a 3-year period at our medical center. Patient records were reviewed and laboratory data were collected. One- to 4-hour corrected count increments (CCIs) were calculated for transfusions given up to 72 hours before receiving these specialized units and the HLA-matched or cross-matched units themselves. RESULTS: Thirty-two patients were identified who received a total of 354 PLT transfusions. Of these, 161 were from unselected apheresis, 152 were cross matched, and 41 were HLA selected. The median CCI for random-donor transfusions was 0 (range, 0 × 10910.5 × 109/L), for cross-matched PLT transfusions 1.7 × 109/L (0 × 109-5.1 × 109/L), and for HLA-matched transfusions 1.2 × 109/L (0 × 109-13.9 × 109/L). Only 25 and 30% of cross-match–compatible or HLA-selected units, respectively, gave 1- to 4-hour CCIs of more than 5.0 × 109/L compared to 12% of the transfusions from random donors. There were no significant differences in the 1- to 4-hour CCIs when comparing random units with HLA-selected or cross-match–compatible units. There was also no significant difference when comparing the HLA-matched and cross-match–compatible PLT units with each other. CONCLUSIONS: The use of cross-match–compatible or HLA-matched units did not provide better increments in PLT count when compared to random nonselected units. Clinical factors may overpower immunologic matching.
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P
oor response or refractoriness is a complication of platelet (PLT) transfusion therapy that can have a significant impact on PLT utilization and clinical outcome.1-12 Both immune and nonimmune factors contribute to PLT consumption and cause a PLT-refractory state.9-16 Immune refractoriness is caused mainly by HLA Class I antibodies.12,15,17-22 Algorithms have been developed to help determine etiology and management of PLT refractoriness.23-25 As the role of HLA antibodies was delineated, methods to select donors using HLA matching were developed18-21 and large pools of HLA-typed PLT donors were established by blood centers.21,26 Subsequently, alloimmunization and PLT refractoriness were linked to white blood cells present in transfused components22,27,28 and a large definitive study showed that leukoreduction could reduce the development of alloimmunization and development of PLT refractoriness.22 This led to the increased use of leukoreduced blood products. As methods for PLT antibody detection were enhanced, a cross-match procedure began to be used for PLT selection instead of using HLA-typed donors.29-36 Studies indicated that HLA and cross-matching are equally effective for selecting compatible units to overcome immunemediated refractoriness.37
ABBREVIATION: PRA = panel-reactive antigen. From the 1Centré Hospitalier de l’Université de Montréal, Montréal, Québec, Canada; and the 2Department of Laboratory Medicine & Pathology and 3Biostatistics and Bioinformatics Core, Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota. Address reprint requests to: Jeffrey McCullough, Department of Laboratory Medicine & Pathology, University of Minnesota, 420 Delaware Street SE, Minneapolis, MN 55455; e-mail: [email protected]. Received for publication January 14, 2014; revision received April 17, 2014, and accepted April 21, 2014. doi: 10.1111/trf.12739 © 2014 AABB TRANSFUSION 2014;54:3080-3087.
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While the immune factors that create a PLT-refractory state can be overcome with HLA or cross-matched units, patients may also have multiple clinical factors that cause accelerated PLT consumption. Distinguishing these immune and nonimmune factors can be difficult to impossible in complicated patients. The corrected count increment (CCI), which is used to determine an adequate response to PLT transfusions,38 does not identify the cause of refractoriness or distinguish between immune and nonimmune factors. While there is a generalized belief that a 1-hour CCI indicates an alloimmune cause for refractoriness, the evidence to back this idea is highly variable.12-15,38 Thus, a low CCI could be due to alloimmune factors or clinical factors in the patient that increase PLT consumption. During the past 20 years, treatment-related mortality after aggressive chemotherapy and hematopoietic stem cell transplantation has improved. However, some patients experience longer periods of aplasia with a resultant increase in blood utilization.39 The consequence may be a higher prevalence and burden of nonimmune PLT consumption factors. These changes may also change the clinical value of HLA-typed or cross-matched PLTs. Since selected or matched products are more costly than standard PLT units, it is important to review their current effectiveness and develop algorithms for their use. We report a 3-year retrospective analysis of patients with PLT refractoriness and response to transfusion of random, cross-match–compatible, and HLA-matched PLT units during the initial hospitalization in which PLT refractoriness occurred.
MATERIALS AND METHODS Patients We conducted a retrospective analysis of all blood bank records at the University of Minnesota Medical Center and identified 56 patients who received either cross-matched or HLA-matched PLT products during that time. Four were excluded because of restricted patient record access. Patients were included in the analysis only if an inpatient hospitalized for chemotherapy or bone marrow transplantation (BMT) weighed more than 10 kg (limit for utilization of half dose of apheresis PLT units at our institution), had a confirmed-positive immune-mediated PLT refractoriness work-up, and received transfusion with crossmatched and/or HLA-matched PLT units during that hospitalization. Thirty-two patients fulfilled these criteria and are the basis of this report. The study was approved by the local institutional review board. A positive immune PLT-refractory work-up was initiated when a patient had a posttransfusion CCI of less than 5.0 × 109/L on two or more usually consecutive occasions. The work-up was considered to be positive either with a PLT cross-match test result showing incompatibility with at least 1 unit
tested or an HLA antibody screen detecting the presence of an HLA Class I antibody against any number of antigens in a single-well test system. While tests were also performed for PLT-specific antibodies, these results were not used to define a positive immune PLT-refractory condition.
Data collection The analysis of the initial episode of PLT transfusion refractoriness was conducted for each patient. For each patient the following data were recorded for the defined hospitalization episode: age; sex; body surface area; diagnostic treatment category (chemotherapy or BMT); HLA typing (Class I); initial PLT cross-match incompatibility result, HLA Class I antibody screen, and human PLT antigen (HPA) antibody screen results; WHO Grade 3 to 4 bleeding episodes; deaths; 1- to 4-hour CCIs; and 4- to 24-hour CCIs. The CCIs included for analysis in this study are limited to the period beginning 72 hours before the first cross-matched or HLA-matched unit up to 72 hours after the last cross-matched or HLA-matched transfusion. The WHO bleeding grade of 3 or 41,2,11 was determined by study personnel during review of the medical record for the period described above.
PLT transfusion refractoriness evaluation The cross-match incompatibility screen, HLA Class I antibody screen, and HPA antibody screen were performed by the American Red Cross, Mid-America Blood Services Division. The cross-match incompatibility screen test is performed with a solid phase system for the detection of IgG antibodies to PLTs (CAPTURE-P, Immucor, Inc., Norcross, GA). The HLA Class I antibody screen and the HPA antibody screen are performed with an assay (PAKPLUS, Gen-Probe GTI Diagnostics, Inc., Waukesha, WI). The definition of immune PLT refractoriness was a positive cross-match for one or more PLT units or a positive HLA antibody test against at least one screening cell.
PLT products supply PLT products (random, cross-match–compatible, and HLA-matched units) were supplied by the American Red Cross, Mid-America Blood Services Division. All PLTs in this study were collected by apheresis. Those designated “random” were selected only based on ABO and Rh type. HLA-matched units were group A, B1U, or B1X match only.20 Cross-reactive groups were considered only in selecting HLA for B1X matches. HLA-matched units were not all tested by cross-match incompatibility. Thus, it is not known whether those units would have been compatible in the cross-match. The HLA antibody avoidance Volume 54, December 2014 TRANSFUSION
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technique was not used because the supplier database does not support this.
CCI calculation CCI calculations for all PLT transfusions were performed according to a previously published formula.1,2,11,12,22 Since the exact PLT content of each unit was not known, a PLT dose of 4 × 1011/L was used for CCI calculation for all units. PLT transfusions without a valid pre- or postcount and a reliable time of transfusion were excluded from analysis. When multiple units were transfused in a short period of time with no intervening PLT count, they had to be excluded from analysis, independently of the overall response to the multiple PLT transfusions. For some parts of this analysis, a 1- to 4-hour CCI of more than 5.0 × 109/L was considered to be a successful transfusion.
TABLE 1. Patient characteristics Number of patients Sex (male/female) Age (years), median (range) Diagnosis Acute myeloid leukemia Others* Treatment category Chemotherapy Transplant†
32 12/20 39.5 (9-67) 14 18 10 22
* Others: dyskeratosis congenita (3), acute lymphoblastic leukemia (2), myelodysplastic syndrome (2), ovarian carcinoma (2), breast carcinoma (1), chronic lymphocytic leukemia (1), thalassemia (1), non-Hodgkin’s lymphoma (1), Hodgkin’s lymphoma (1), multiple myeloma (1), Fanconi anemia (1), dystrophic epidermolysis bullosa (1), and cerebral adrenoleukodystrophy (1). † Transplant: 21 allogeneic transplants and one autologous transplant.
Statistical analysis The number of successful transfusions per patient, as determined by a CCI of more than 5.0 × 109/L (1-4 hr, 4-24 hr), was modeled as a Poisson variable. We compared the average success rate between the three types of PLT transfusions (random, cross-match–compatible, and HLA-matched units). Since some patients received both cross-matched and HLA-matched units, a generalized estimating equation model was used, which allows for repeated observations on the same patient. In this study most patients received more than one type of transfusion. The covariance structure between the repeated transfusion types was specified as unstructured for the majority of analyses. In one case where the data were very sparse, the independent variance and covariance structure was utilized. The comparisons between the three types of PLT transfusions were performed pairwise. The analysis assumes that the order in which the patient received the different types of transfusions was unrelated to whether or not the transfusion was successful.
RESULTS There were 32 patients in the study, most of whom had undergone a hematopoietic stem cell transplantation (Table 1). All patients were tested for HLA antibodies, PLTspecific antibodies, and also for cross-match incompatibility (Table 2). Nine had PLT-specific antibodies. During the period of study, the patients received a total of 354 transfusions for which pretransfusion and 1- to 4-hourposttransfusion PLT counts were available (Table 3). A total of 161 of 354 (45%) were random-donor units, 152 (42%) were selected by cross-match, and 41 (13%) were HLA matched (Table 3). The transfusions with randomdonor units were all given within 72 hours before the first use of HLA- or cross-matched units. As expected, the 1- to 4-hour CCIs from the random-donor units were low, with 3082
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TABLE 2. Type of selected PLT products provided to patients in this study Type of PLT product HLA selected Cross match selected HLA and cross match Total
Number of patients 11 10 11 32
a median of 0 (zero), and a range of 0 × 109 to 10.5 × 109/L. Cross-match–compatible units gave a median 1- to 4-hour CCI of 1.7 × 109/L and the HLA-matched transfusions gave a median 1- to 4-hour CCI of 1.2 × 109/L. While some transfusions resulted in higher CCIs (10.5 × 109, 15.1 × 109, and 13.9 × 109/L) the change in PLT count after most transfusions was small. One transfusion of a B1X match resulted in a CCI of 13.9 × 109/L while other transfusions to this patient had CCIs of zero. We arbitrarily selected a CCI of 5.0 × 109/L as representing a satisfactory response to transfusion.22 As expected, only 12% of random-donor units gave this response. While cross-matched and HLA-matched transfusions gave a higher response rate, this was disappointingly low at 25 and 29%, respectively (Table 4). Thus, as expected, most random-donor transfusions (88%) gave poor responses, but surprisingly 75 and 71% of crossmatched and HLA-selected units also gave poor responses (Table 4). The generalized estimating equation model takes into account that the same patient may have received more than one type of transfusion when comparing the average number of successful transfusions per patient for random versus cross-match compatible, random versus HLA, and cross-match compatible versus HLA (Tables 5, 6, and 7). A successful transfusion was defined as a 1- to 4-hour or 4to 24-hour CCI of more than 5 × 109/L. While the crossmatch was 2.06 times more likely than random-donor
CROSS-MATCHED OR HLA-MATCHED PLT TRANSFUSION
TABLE 3. Evaluation of CCIs between random, cross-match–compatible, and HLA-matched PLT transfusion* Selection method
Number of units
Random Cross match HLA match Total
161 152 41 354
1- to 4-hr CCI (×109/L) Median Range 0 1.7 1.2
Number of units
0-10.5 0-15.0 0-13.9
109 60 7 176
4- to 24-hr CCI (×109/L) Median Range 0 0 3.3
0-11.6 0-14.3 1.4-8.7
* CCI calculations are limited to the period up to 72 hours before the use of the first cross-matched and HLA-matched PLT unit to 72 hours after the last cross-matched and HLA-matched PLT unit.
TABLE 4. Response to transfusion using a CCI of 5.0 × 109/L as a satisfactory response 1- to 4-hr CCI > 5.0 (×109/L) Selection methods Random Cross match HLA match
Number of units
Number
%
161 152 41
19 38 12
12 25 29
4- to 24-hr CCI > 5.0 (×109/L) Number of units Number 109 60 7
%
7 11 3
6 18 43
TABLE 5. Average number of successful PLT transfusions (CCI > 5.0 × 109/L) per patient between cross-match–compatible and random units (n = 30 patients) CCI 1 to 4 hr (n = 52) 4 to 24 hr (n = 45)
Successful cross-match compatible (C) transfusions per patient 0.25 0.19
Successful random (R) transfusions per patient 0.12 0.06
Ratio (95% CI) of average number of successful transfusions (C/R) 2.06 (1.20-3.53) 2.97 (1.23-7.21)
p value 0.057 0.110
TABLE 6. Average number of successful PLT transfusions (CCI > 5.0 × 109/L) per patient between HLA-matched and random units (n = 29 patients) CCI 1 to 4 hr (n = 35) 4 to 24 hr (n = 28)
Successful HLA match (H) transfusions per patient 0.30 0.44
Successful random (R) transfusions per patient 0.12 0.06
Ratio (95% CI) of average number of successful transfusions (H/R) 2.47 (1.24-4.92) 6.86 (3.47-13.57)
p value 0.110 0.283
TABLE 7. Average number of successful PLT transfusions (CCI > 5.0 × 109/L) per patient between HLA-matched and cross-match–compatible units (n = 31 patients) CCI 1 to 4 hr (n = 39) 4 to 24 hr (n = 25)
Successful HLA match (H) transfusions per patient 0.32 0.43
Successful cross-match compatible (C) transfusions per patient 0.24 0.18
PLTs to provide a successful 1- to 4-hour result and 2.97 times more likely to provide a successful 4- to 24-hour result, the average number of successful transfusions was still low, being 0.25 for cross-matched compared to 0.12 for random-donor units (Table 5). These frequencies of successful transfusion were not different from randomdonor units, although this was a small study and may not have had adequate power. For random-donor units compared to HLA selected, the HLA-selected units were 2.47 and 6.86 times more likely to give a successful transfusion at 1 to 4 and 4 to 24 hours posttransplant, respectively (Table 6). However, this difference in this small study was
Ratio (95% CI) of average number of successful transfusions (H/C) 1.33 (0.65-2.73) 2.34 (0.68-8.08)
p value 0.564 0.266
not significant and the average number of 1- to 4-hour successful transfusions was still very low at 0.3 for HLAselected compared to 0.12 for random-donor units and 4to 24-hour transfusions 0.44 for HLA and 0.06 for random units (Table 6). When HLA-selected units were compared with cross-matched units, the HLA-selected units were 1.33 and 2.34 times more likely to give a successful 1- to 4and 4- to 24-hour transfusion (Table 7). To better understand the relative effectiveness of HLA compared to cross-matched PLT units, we examined the proportion of cross-match incompatibility against the presence of HLA antibodies. When no HLA antibodies Volume 54, December 2014 TRANSFUSION
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TABLE 8. Relationship between proportion of positive cross-matched units and HLA antibody screen HLA antibody Negative (n = 10) Positive
50% cross-matched units incompatibility 3/10
3/11
8/11†
* Number of incompatible PLT products: 1/14, 4/14, 7/14, 3/13, 2/14, 2/14, and 1/14. † Number of incompatible PLT products: 11/14, 11/14, 8/8, 14/14, 11/14, 9/14, 9/12, and 12/14.
were found in the screening test, seven of 10 patients had less than 50% cross-match–incompatible units (Table 8). Conversely, when the HLA antibody test was positive, eight of 11 patients had cross-match–incompatible rates of more than 50%. Thus, when HLA antibodies were present, there was a higher likelihood of finding crossmatch–incompatible units. Since we used a screening test for HLA antibodies, we cannot correlate the strength of the HLA antibodies, in terms of the panel-reactive antigen (PRA) with the cross-match assay. It has been reported that a PRA greater than 20% suggests PLT refractoriness;40 however, to our knowledge, data adjusting the PRA with additional information about antibody strength (mean fluorescent intensity) is currently lacking. It is also interesting to note that the detection of PLT-specific antibodies on the screening test did not correlate with refractoriness (data not shown). While it has been reported that PLT specific antibodies (HPA) can cause refractoriness,41 our limited data are not adequate to determine whether HPA antibodies are an important cause of refractoriness. In refractory patients, the value of HLA matching outweighs the detriment of ABO mismatching.20 In this study, PLTs were either ABO identical or compatible with the patient—none were incompatible containing ABO antigens to which the patients had antibodies. Since the purpose of PLT transfusions is control or prevention of bleeding, we determined the rate of WHOgraded bleeding in these patients. Despite the lack of response to PLT transfusion, only six of the 32 patients experienced WHO Grade 3 or 4 bleeding (Table 9). Five of these were hemorrhagic cystitis and one involved pulmonary hemorrhage. There were seven deaths in these 32 patients, two of which were considered by the attending physicians to be related to hemorrhage. One involved hemorrhagic cystitis and one pulmonary hemorrhage.
DISCUSSION In this study, only 25 and 29% of transfusions of crossmatched or HLA-matched PLTs provided a CCI that was considered to represent a successful transfusion. While this is better than the 12% successful random-donor 3084
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TABLE 9. Bleeding outcomes in the 32 PLT-refractory patients Outcome WHO Grade 3-4 bleeding Hemorrhagic cystitis Pulmonary hemorrhage Deaths Hemorrhagic deaths Hemorrhagic cystitis Pulmonary hemorrhage
Number 6 5 1 7 2 1 1
Percent 19
22 6
transfusions, the effectiveness of HLA- or cross-matched PLT transfusions in these patients was of limited value. However, to some extent this might not be surprising. Some PLT refractory patients with no complicating factors do not have HLA antibodies.12,15 Conversely, most patients with HLA antibodies9,22,23,35 have a poor response to transfusion, although some do have a satisfactory response.22,40,41 In original studies of HLA matching for refractory patients by Duquesnoy and colleagues,20 they showed similar responses to transfusion for different degrees of mismatch. This led to the development of files of HLA-typed donors and the implementation of HLA matching as one of the strategies for managing patents refractory to PLT transfusion. However, in those studies the range of responses for different HLA matches was similar.20 Thus, many transfusions of well-matched units gave a poor response and many poorly matched transfusions gave a good response. Overall, 20% to 50% of HLAmatched transfusions did not give a good response.19,20 The data did not allow comparison of the number of “good” responses to poor responses in individual patients since the point was to demonstrate that some mismatching could give effective transfusions. Data from others37,42 showed similar results and so failure of many wellmatched donor units is not unexpected. All of the HLAselected units in our study were A, B1U, or B1X match grade so we could have expected satisfactory mean responses from those transfusions. Pavenski and coworkers43 summarized 30 reports of the effect of HLA-matched PLT transfusions and concluded that “use of HLA matched leukoreduced PLTs was associated with a higher increment . . . compared to random-donor leukoreduced PLTs.” However, most of the studies covered in this report are from the 1970 to 1990 era and the current clinical situations may differ from those at the time covered by Pavenski and colleagues.43 As PLT antibody techniques were refined and the failure rate of up to 50% of HLA-matched transfusions was recognized, interest developed in PLT cross matching. The positive predictive value of various PLT cross-match techniques ranged from 73% to 100% and the negative predictive value from 52% to 92%.44 However, many of these studies were retrospective and some of the prospective studies did not even use fresh PLTs for cross-match
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testing. A solid-phase red blood cell (RBC) adherence assay which is now in widespread use (although periodically unavailable) originally predicted a successful transfusion outcome in 97% of patients with no clinical factors that might cause nonimmune PLT destruction34,35 and other studies36 suggested that the solid phase RBC adherence assay was superior to HLA matching, but from the aggregate experience, it is not unexpected that some transfusions that are compatible in a PLT cross-match do not give a good response. PLT-specific antibodies are not usually related to poor response to transfusions,15,22,44 but our data were not adequate to determine this. In this study, we used HLA matching but not the HLA avoidance technique in which the antigen corresponding to known HLA antibody specificities is avoided.45,46 It is possible that this could have given better responses compared with the HLA matching technique, although Petz and colleagues46 found similar results of HLA matching and the HLA antigen avoidance method. There are several limitations to our study. The number of patients and number of HLA-matched transfusions were small. Patients were not randomized to receive either HLA- or cross-matched PLTs. Cross-matched PLTs were usually used first because they were readily available whereas HLA-matched donors needed to be contacted and scheduled for donation. Even small increases in PLT count or low numbers of circulating PLTs can be effective in providing hemostasis,1 so it is possible that the HLA or cross-match transfusions were clinically effective. Hematology, oncology, and stem cell transplantation have evolved considerably since the early work on HLA selection and even the work on PLT cross-matching. Chemotherapy is more aggressive resulting in greater toxicity, stem cell transplants are more widely used with different stem cell sources especially cord blood and performed in older patients or those at higher risk. Patients are more complicated and thus may have the presence of more factors known to interfere with successful PLT transfusion. For instance, sepsis, fever, graft-versus-host disease, bleeding, antibiotics, and amphotericin therapy are established factors that reduce the transfusion response.9,12-16 The source of stem cells for transplant affects the duration to engraftment and thus cord blood transplant patients use considerably more products.39 Although we did not study this, it seems likely that these complicating factors may have overpowered the value of HLA and cross matching. A poor response to PLT transfusion often occurs in very complex patients and in one study, 80% of patients who died were refractory to PLT transfusion.47 It has been estimated that a substantial proportion of refractory patients are due to nonimmune (clinical) factors.5,9,10,13,14,16,48 This portion may be even higher presently, thus further reducing the value of specially matched PLTs. Another possible reason for a greater impact of nonimmune factors is that the widespread use of
leukoreduction has reduced the likelihood of alloimmunization, thus resulting in a higher proportion of PLT refractoriness being due to nonimmune factors. Thus, in conclusion, it is possible that the evolution in patient care especially of stem cell transplantation has led to more complicated patients with more clinical factors that have impact on the PLT posttransfusion increment. Such patients cannot be managed by immunologic matching. Immunologic matching for PLT-refractory patients may no longer be of value in many patients, although our study is small and a larger prospective randomized controlled trial is warranted. Therefore, we recommend that either or both HLA matching and cross matching be attempted for two transfusions and, if unsuccessful, regular randomdonor units be used. This approach is also consistent with recent observations that a low dose of PLTs is equally effective as the current standard dose in controlling or preventing bleeding and that bleeding is no more likely at PLT counts between 5.0 × 109 and 80.0 × 109/L.1 CONFLICT OF INTEREST The authors have disclosed no conflicts of interest.
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