Tocilizumab reduces hypercoagulation in COVID-19 - Perspectives from the coagulation and immunomodulation Covid assessment (Coag-ImmCovA) clinical trial.

BACKGROUND: Despite medical interventions, COVID-19 continues to persist at pandemic proportions. A hypercoagulation state was rapidly observed in the severely ill, and the incidence of thromboembolic events remains elevated. Interleukin inhibitors have demonstrated positive effects on the hyperactivation of the immune system in COVID-19, with the interleukin-6 inhibitor tocilizumab showing promising results in reducing mortality. Nevertheless, the impact of interleukin inhibitors on the coagulation system remains incompletely understood. METHODS: In this clinical trial conducted in Stockholm, Sweden, interleukin inhibitors, namely anakinra (ANA) or tocilizumab (TOCI), were randomly administered in addition to standard care (SC) to hospitalized patients with COVID-19. A control group received only SC. The primary outcome sought to measure effects on global hemostasis, as indicated by changes in functional coagulation tests, specifically Rotational Thromboelastometry (ROTEM) or Overall Hemostatic Potential (OHP), visualized through scanning electron microscopy images. Secondary outcomes included effects on conventional coagulation laboratory tests. RESULTS: The study enrolled 74 patients who were randomized to receive either ANA or TOCI in addition to SC, or SC alone. In the TOCI group, ROTEM variables exhibited less hypercoagulation after 29 days compared with ANA or SC treatment groups, characterized by prolonged clot formation time and decreased clot firmness. OHP decreased, but there were no significant differences among the three treatment groups. Plasma fibrinogen levels, initially elevated, decreased significantly in TOCI recipients over time. CONCLUSION: Tocilizumab treatment demonstrated a significant reduction of hypercoagulation in hospitalized COVID-19 patients, by improvements in both global coagulation tests and conventional laboratory tests, in comparison with anakinra or SC alone. This finding underscores the significance of tocilizumab as a viable treatment option in severe COVID-19 cases, with the potential to decrease thrombosis incidence.

The role of complement and extracellular vesicles in the development of pulmonary embolism in severe COVID-19 cases.

Complement and extracellular vesicles (EVs) association with thrombogenic tendencies is acknowledged, but limited evidence exists for their link to COVID-19 venous thromboembolism. This study aims to examine the relationship between pulmonary embolism and the expression of complement and other proteins related to thrombogenesis in severe Covid-19 patients. We included prospectively 207 severe COVID-19 patients and retrospectively screened for pulmonary embolism (PE). This analysis comprises 20 confirmed PE cases and 20 matched patients without PE. Blood samples taken at the admission in the intensive care unit were analyzed for complement using ELISA. EVs derived from neutrophils, endothelium, or platelets, as well carrying complement or tissue factor were analyzed using flow cytometry. Complement levels were markedly elevated, with a notable increase in C3a and Terminal Complement Complex. The most prevalent EV population was identified as tissue factor (TF)-carrying EVs which peaked in patients with PE during ICU days 4-9. However, for both the complement and analyzed EV populations, no statistically significant differences were found between the patients who developed pulmonary embolism and those who did not. In conclusion, complement factors and EVs expressing tissue factor, along with EVs derived from endothelial cells and platelets, are elevated in severe COVID-19 patients, regardless of the presence of pulmonary embolism. However, the involvement of complement and procoagulant EVs in peripheral plasma in the development of pulmonary embolism is still unclear and requires further investigation.

Global Hemostatic Methods to Tailor Treatment With Bypassing Agents in Hemophilia A With Inhibitors- A Single-Center, Pilot Study.

For patients with hemophilia A and high-titer inhibitors treated with bypassing agents there are no reliable methods to assess treatment effect. We investigated the utility of global hemostatic methods in assessing treatment with bypassing agents (rFVIIa or activated prothrombin complex [aPCC]). All patients with hemophilia A and inhibitors followed at the Coagulation Unit or the Pediatric Coagulation Unit at Karolinska University Hospital aged 6 years and above were eligible for this noninterventional study. Baseline plasma samples were spiked with bypassing agents in increasing concentrations (aPCC 50 U/kg, 100 U/kg, 150 U/kg, and rFVIIa 90 µg/kg and 270 µg/kg) in vitro. For patients treated with factor concentrates or bypassing agents follow-up samples were collected (in vivo tests). The samples were analyzed using overall hemostatic potential (OHP), and calibrated automated thrombogram, Calibrated Automated Thrombogram (CAT). Nine patients with hemophilia A with inhibitors were included. Spiking with rFVIIa normalized the coagulation potential in 6/8 samples, in 3 only with high dose. Only one sample did not improve adequately after spiking with aPCC. The improvement in hemostasis was reliably shown by both CAT and OHP. The baseline potential was, however, more often measurable by OHP compared to CAT. Factor concentrate had been administered to 5 patients normalizing the hemostatic potential in vivo in 2 (without spiking). The hemostatic improvement induced by spiking with rFVIIa or aPCC is shown by OHP and CAT, but the results have to be evaluated in larger cohorts.

Effect of prothrombin Belgrade mutation, causing antithrombin resistance, on fibrin clot properties.

INTRODUCTION: Prothrombin Belgrade mutation is the result of the c.1787G>A substitution in the prothrombin gene. It is located in the antithrombin and sodium binding site and leads to impaired inactivation of thrombin by antithrombin, resulting in antithrombin resistance and thrombotic disorders. However, it negatively affects sodium binding and may have hypocoagulant effects. Considering that prothrombin Belgrade mutation mechanism is still not fully elucidated and that sodium binding is important for thrombin affinity towards fibrinogen, our aim was to determine whether this mutation affects fibrin clot formation and lysis. METHODS: Using HEK293T cell line, recombinant wild type and mutated prothrombin were generated by transient transfection. Samples that correspond to plasma of a non-carrier, heterozygous and homozygous carriers were reconstituted using prothrombin deficient plasma and recombinant proteins. Reconstituted samples were used in OHP assay (Overall Hemostasis Potential) to determine kinetic profiles of coagulation and fibrinolysis. Clot turbidity assay was performed to observe kinetics of clot formation and lysis more closely. Fibrin clots formed in reconstituted plasma samples were analyzed by confocal microscopy to determine density of fibrin network. Fibrin clots were additionally observed using electron microscopy to determine thickness of individual fibrin fibers. RESULTS: No significant difference found in OHP, OCP, OFP, and fibrin network density between wild type, heterozygous, and homozygous carrier reconstituted plasma samples. There were significant differences between samples for slope and slope time parameters in kinetic profiles and fibrin fiber thickness. CONCLUSIONS: Results indicate that prothrombin Belgrade mutation has no significant impact on fibrinolysis, however it may affect kinetics of clot formation and its architecture.

Clinical Implications of Discrepancy between One-Stage Clotting and Chromogenic Factor IX Activity in Hemophilia B.

BACKGROUND: Discrepancy in factor IX activity (FIX:C) between one-stage assay (OSA) and chromogenic substrate assay (CSA) in patients with hemophilia B (PwHB) introduces challenges for clinical management. AIM: To study the differences in FIX:C using OSA and CSA in moderate and mild hemophilia B (HB), their impact on classification of severity, and correlation with genotype. METHODS: Single-center study including 21 genotyped and clinically characterized PwHB. FIX:C by OSA was measured using ActinFSL (Siemens) and CSA by Biophen (Hyphen). In addition, in vitro experiments with wild-type FIX were performed. Reproducibility of CSA was assessed between three European coagulation laboratories. RESULTS: FIX:C by CSA was consistently lower than by OSA, with 10/17 PwHB having a more severe hemophilia type by CSA. OSA displayed a more accurate description of the clinical bleeding severity, compared with CSA. A twofold difference between OSA:CSA FIX:C was present in 12/17 PwHB; all patients had genetic missense variants in the FIX serine protease domain. Discrepancy was also observed with diluted normal plasma, most significant for values below 0.10 IU/mL. Assessment of samples with low FIX:C showed excellent reproducibility of the CSA results between the laboratories. CONCLUSION: FIX:C was consistently higher by OSA compared with the CSA. Assessing FIX:C by CSA alone would have led to diagnosis of a more severe hemophilia type in a significant proportion of patients. Our study suggests using both OSA and CSA FIX:C together with genotyping to classify HB severity and provide essential information for clinical management.

Extracellular vesicles in plasma and cerebrospinal fluid in patients with COVID-19 and neurological symptoms.

INTRODUCTION: Increased levels of extracellular vesicles (EVs) are associated with haemostatic disturbances in various clinical settings. However, their role in COVID-19 patients is still not fully clear. In the present study we investigated EVs in plasma from patients with COVID-19 and neurological symptoms in relation to the activation of coagulation. METHODS: Nineteen COVID-19 patients with neurological symptoms and twenty-three aged-matched healthy individuals were included. Global coagulation assays were performed and levels of EVs were determined by flow-cytometry in plasma and cerebrospinal fluid (CSF). RESULTS: A procoagulant state characterized by significantly increased overall coagulation- (OCP) and overall haemostatic potential (OHP), diminished overall fibrinolytic potential (OFP) together with a denser fibrin structure was found in patients with COVID-19. Flow cytometry revealed elevated levels of plasma circulating EVs derived from neutrophils (MPO+) and platelets (CD61+), as well as EVs expressing phosphatidylserine (PS+) and complement component C5b-9 (TCC+) in patients with COVID-19 compared with controls. The concentrations of PS+, CD61+ and TCC+ EVs were positively correlated with OCP and OHP in COVID-19 patients. Moreover, we identified CD61+, MPO+ and endothelial cell-derived EVs, as well as EVs exposing PS and TCC in the CSF of patients suffering from neurological symptoms during COVID-19. CONCLUSION: The unique finding in this study was the presence of EVs in the CSF of COVID-19 patients with neurologic manifestations as well as higher expression of complement protein on circulating plasma EVs. EVs may indicate blood-brain barrier damage during SARS-COV-2 infection.

Elevated plasma complement factor H related 5 protein is associated with venous thromboembolism.

Venous thromboembolism (VTE) is a common, multi-causal disease with potentially serious short- and long-term complications. In clinical practice, there is a need for improved plasma biomarker-based tools for VTE diagnosis and risk prediction. Here we show, using proteomics profiling to screen plasma from patients with suspected acute VTE, and several case-control studies for VTE, how Complement Factor H Related 5 protein (CFHR5), a regulator of the alternative pathway of complement activation, is a VTE-associated plasma biomarker. In plasma, higher CFHR5 levels are associated with increased thrombin generation potential and recombinant CFHR5 enhanced platelet activation in vitro. GWAS analysis of ~52,000 participants identifies six loci associated with CFHR5 plasma levels, but Mendelian randomization do not demonstrate causality between CFHR5 and VTE. Our results indicate an important role for the regulation of the alternative pathway of complement activation in VTE and that CFHR5 represents a potential diagnostic and/or risk predictive plasma biomarker.

Biological Variation in Rotational Thromboelastometry in Patients with Atrial Fibrillation Receiving Rivaroxaban.

Rotational thromboelastometry (ROTEM) is a viscoelastic hemostasis test used primarily in the management of bleeding after trauma or in cardiac surgery. To allow safe and valid clinical interpretation of test results, objective specifications for analytical performance are needed, which are generally based on biological variation within (CVI) and between (CVG) individuals. The aim of this study was to evaluate biological variation in ROTEM in patients receiving rivaroxaban. Sixty patients with atrial fibrillation on stable rivaroxaban therapy were included, from whom blood was collected on six occasions: three times at trough and three at peak rivaroxaban concentrations. ROTEM® Extem and LowTF were measured as well as rivaroxaban concentration, PT, APTT, and anti-Xa. Within- (CVI) and between-subject (CVG) biological estimates were calculated. Knowledge of these biological variation components will help to establish the appropriate objective analytical performance specifications for ROTEM analysis.

[Routine screening with APTT is not indicated before surgery]. / Rutinmässig screening med APTT är inte indicerad före operation.

Activated partial thromboplastin time (APTT) is widely practiced in preoperative screening. The value of using this test to predict the risk of perioperative bleeding is not well documented in Sweden. In this article, a literature review is performed to determine whether unselected APTT testing can predict abnormal perioperative bleeding. The current literature does not support coagulation screening with APTT in routine perioperative bleeding assessment, as preoperative screening with APTT has a low sensitivity for detection of clinically significant bleeding disorder. While a comprehensive bleeding history is crucial, the APTT test should only be performed on patients with a history of increased bleeding tendency. The conclusion of this literature review is that patients with a negative bleeding history do not require routine screening with APTT prior to surgery, which, if implemented, would lead to a more cost-effective perioperative routine.

Platelet function testing: Current practice among clinical centres in Northern Europe.

INTRODUCTION: Platelet function tests are used to screen and diagnose patients with possible inherited platelet function defects (IPFD). Some acquired platelet dysfunction may be caused by certain drugs or comorbidities, which need to be excluded before testing. AIMS: To identify current practice among centres performing platelet function tests in Northern Europe. METHODS: A total of 14 clinical centres from Sweden (six), Finland (two), Denmark (two), Norway (one), Estonia (two) and Iceland (one) completed the survey questionnaire, the population capture area of about 29.5 million. RESULTS: Six of the 14 (42.8%) centres providing platelet function assessment represent comprehensive treatment centres (EUHANET status). A Bleeding score (BS) or ISTH bleeding assessment tool (ISTH BAT score) is evaluated in 11/14 (78.6%) centres and family history in all. Five/14 centres (35.7%) use structured preanalytical patient instructions, and 10/14 (71.4%) recorded questionnaire on the preassessment of avoidance of any drugs or natural products affecting platelet functions. Preliminary investigations of screening tests of coagulation are performed in 10/14 (71.4%), while in 4/14 (28.6%), the diagnostic work-up of IPFD and von Willebrand disease (VWD) is performed simultaneously. The work-up of IPFD includes peripheral blood smear in 10/14 (71.4%), platelet aggregometry in all, flow cytometry in 10/14 (71.4%) and Platelet Function Analysis (PFA) in 3/11 (28.6%). Molecular genetic diagnosis is available in 7/14 (50%) centres. CONCLUSIONS: The considerable variability in the current practice illustrates the need for harmonization between the Northern European centres according to the international registers (i.e. EUHASS) and IPFD guidelines (ISTH, EHA).

Using a low-molecular weight heparin-calibrated anti-factor Xa assay to assess the concentration of apixaban and rivaroxaban.

INTRODUCTION: Direct oral anticoagulant (DOAC)-inhibiting factor Xa (FXa-DOAC) are being increasingly used as prophylaxis of venous thromboembolism and for prevention of stroke in patients with atrial fibrillation. In contrast to vitamin K antagonists, DOACs do not require monitoring in general. However, it is sometimes of value in the acute setting, for instance when considering a reversal agent in uncontrolled bleeding in patients on DOAC. METHODS: We evaluated if a low-molecular weight heparin (LMWH)-calibrated anti-factor Xa assay could be used to estimate FXa-DOAC concentration in the concentration range <100 ng/mL by spiking known concentrations of FXa-DOAC and from those result calculate the FXa-DOAC concentration from the response of the LMWH assay. This procedure was then evaluated by comparing the result with a drug-calibrated chromogenic assay and liquid chromatography tandem mass spectrometry (LC-MS/MS) on clinical plasma samples from patients treated with apixaban or rivaroxaban. RESULTS: Although the measuring range was narrower for the LMWH-calibrated assay, concentrations recalculated from the LMWH assay was comparable with those measured by the drug-calibrated method when compared with LC-MS/MS. CONCLUSION: We suggest that an LMWH-calibrated anti-factor Xa assay can be used after characterization of the response of FXa-DOACs to give guidance on the concentration of apixaban and rivaroxaban. Shorter turnaround time than LC-MS/MS and the greater availability than drug-calibrated chromogenic assays could make this a valuable option in the acute setting.

Predictive Ability of a Clinical-Genetic Risk Score for Venous Thromboembolism in Northern and Southern European Populations.

Venous thromboembolism (VTE) is a complex, multifactorial problem, the development of which depends on a combination of genetic and acqfiguired risk factors. In a Spanish population, the Thrombo inCode score (or TiC score), which combines clinical and genetic risk components, was recently proven better at determining the risk of VTE than the commonly used model involving the analysis of two genetic variants associated with thrombophilia: the Factor V Leiden (F5 rs6025) and the G20210A prothrombin (F2 rs1799963). The aim of the present case-control study was to validate the VTE risk predictive capacity of the TiC score in a Northern European population (from Sweden). The study included 173 subjects with VTE and 196 controls. All were analyzed for the genetic risk variants included in the TiC gene panel. Standard measures -receiver operating characteristic (ROC) area under the curve (AUC), sensitivity, specificity, and odds ratio (OR)-were calculated. The TiC score returned an AUC value of 0.673, a sensitivity of 72.25%, a specificity of 60.62%, and an OR of 4.11. These AUC, sensitivity, and OR values are all greater than those associated with the currently used combination of genetic variants. A TiC version adjusted for the allelic frequencies of the Swedish population significantly improved its AUC value (0.783). In summary, the TiC score returned more reliable risk estimates for the studied Northern European population than did the analysis of the Factor V Leiden and the G20210A genetic variations in combination. Thus, the TiC score can be reliably used with European populations, despite differences in allelic frequencies.

Apixaban concentration variability and relation to clinical outcomes in real-life patients with atrial fibrillation.

In some clinical situations, measurements of anticoagulant effect of apixaban may be needed. We investigated the inter- and intra-individual apixaban variability in patients with atrial fibrillation and correlated these results with clinical outcome. We included 62 patients receiving either 5 mg (A5, n = 32) or 2.5 mg (A2.5, n = 30) apixaban twice-daily. We collected three trough and three peak blood samples 6-8 weeks apart. Apixaban concentration was measured by liquid chromatography-tandem mass-spectrometry (LC-MS/MS) and by anti-Xa. Patients on A2.5 were older, had lower creatinine clearance, higher CHA2DS2VASc (4.7 ± 1.0 vs. 3.4 ± 1.7) and lower trough (85 ± 39 vs. 117 ± 53 ng/mL) and peak (170 ± 56 vs. 256 ± 91 ng/mL) apixaban concentrations than patients on A5 (all p < 0.01). In patients on A5, LC-MS/MS showed a significant difference between through levels and between peak levels (p < 0.01). During apixaban treatment, 21 patients suffered bleeding (2 major). There was no association between bleeding and apixaban concentrations or variability. Four patients who suffered thromboembolic event had lower peak apixaban concentrations than patients without it (159 ± 13 vs. 238 ± 88 ng/mL, p = 0.05). We concluded, that there was a significant intra- and inter-individual variability in apixaban trough and peak concentrations. Neither variability nor apixaban concentrations were associated with clinical outcomes.

Platelet Count Rose While D-Dimer Levels Dropped as Deaths and Thrombosis Declined-An Observational Study on Anticoagulation Shift in COVID-19.

BACKGROUND: High levels of D-dimer and low platelet counts are associated with poor outcome in coronavirus disease 2019 (COVID-19). As anticoagulation appeared to improve survival, hospital-wide recommendations regarding higher doses of anticoagulation were implemented on April 9, 2020. OBJECTIVES: To investigate if trends in D-dimer levels and platelet counts were associated with death, thrombosis, and the shift in anticoagulation. METHODS: Retrospective cohort study of 429 patients with COVID-19 at Karolinska University Hospital. Information on D-dimer levels and platelet counts was obtained from laboratory databases and clinical data from medical records. RESULTS: Thirty-day mortality and thrombosis rates were 19% and 18%, respectively. Pulmonary embolism was common, 65/83 (78%). Increased D-dimer levels in the first week in hospital were significantly associated with death and thrombosis (odds ratio [OR]: 6.06; 95% confidence interval [CL]: 2.10-17.5 and 3.11; 95% CI: 1.20-8.10, respectively). If platelet count increased more than 35 × 109/L per day, the mortality and thrombotic risk decreased (OR: 0.16; 95% CI: 0.06-0.41, and OR: 0.36; 95% CI: 0.17-0.80). After implementation of updated hospital-wide recommendations, the daily mean significantly decreased regarding D-dimer levels while platelet counts rose; -1.93; 95% CI: -1.00-2.87 mg/L FEU (fibrinogen-equivalent unit) and 65; 95% CI: 54-76 ×109/L, and significant risk reductions for death and thrombosis were observed; OR: 0.48; 95% CI: 0.25-0.92 and 0.35; 95% CI: 0.17-0.72. CONCLUSION: In contrast to D-dimer levels, increase of platelet count over the first week in hospital was associated with improved survival and reduced thrombotic risk. The daily mean levels of D-dimer dropped while the platelet counts rose, coinciding with increased anticoagulation and a decline in thrombotic burden and mortality.

The in vitro addition of idarucizumab to plasma samples from patients increases thrombin generation.

Dabigatran interferes with many coagulation tests. To overcome this obstacle the use of idarucizumab as an in vitro antidote to dabigatran has been proposed. The aim of this study was to test the effect of idarucizumab as an in vitro antidote to dabigatran in ex vivo plasma samples from routine clinical patients examined by a thrombin generation assay (TGA). From 44 patients with atrial fibrillation five blood samples were collected. Thrombin generation was measured in all samples before and after the addition of idarucizumab. When idarucizumab was added to baseline plasma (no dabigatran), it caused a significantly shorter Lag Time and Time to Peak Thrombin, and a higher Peak Thrombin and Endogenous Thrombin Potential (ETP) of TGA. Similar results were obtained when idarucizumab was added to dabigatran-containing plasma, with TGA parameters comparable to baseline + idarucizumab plasma, but not to baseline plasma. In summary, our study showed that in vitro addition of idarucizumab to plasma samples from patients increases thrombin generation. The use of idarucizumab to neutralize dabigatran in patient plasma samples as well as the clinical relevance of in vitro increased thrombin generation induced by idarucizumab needs further investigation.

Genetics and Hemostatic Potential in Persons with Mild to Moderate Hemophilia A with a Discrepancy between One-Stage and Chromogenic FVIII Assays.

BACKGROUND: Factor VIII (FVIII) activity (FVIII:C) can be measured by different methods including one-stage clotting assays (OSAs) and chromogenic assays (CSAs). Discrepancy between FVIII:C assays is known and associated with genetic variations causing mild and moderate hemophilia A (HA). We aimed to study the discrepancy phenomenon and to identify associated genetic alterations. Further, we investigated if hemostatic global assays could discriminate the group with discrepant FVIII:C from them. METHODS: The study contained plasma samples from 45 patients with HA (PwHA) from Hemophilia Centers in Stockholm, Sweden, and Belgrade, Serbia. We measured FVIII:C with OSA and CSA, sequenced the F8 gene, and performed two global hemostatic assays; endogenous thrombin potential and overall hemostatic potential. RESULTS: Nineteen of 45 PwHA had a more than twofold higher FVIII:C using OSA compared to CSA and were considered discrepant. Thirty-four causal mutations were detected, where of five had not previously been associated with assay discrepancy. These novel mutations were p.Tyr25Cys, p.Phe698Leu, p.Met699Leu, p.Ile1698Thr, and Ala2070Val. We found no difference between discrepant and nondiscrepant cases with either of the global assays. CONCLUSION: There was a discrepancy between FVIII:C assays in almost half of the PwHA, which for some could lead to missed HA diagnoses or misclassification of severity. Genotyping confirmed that mutations associated with FVIII:C discrepancy cluster in the A domains of F8, and five mutations not previously associated with FVIII:C discrepancy was identified. Global hemostatic assays did not contribute to distinguish assay discrepancy in PwHA.

Overall hemostasis potential and aPTT-clot waveform analysis as powerful laboratory diagnostic tools for identification of hemophilia A patients with unexpected bleeding phenotype.

INTRODUCTION: Traditionally used laboratory methods do not always accurately reflect bleeding severity in hemophilia A (HA) patients. The ability of three global assays for identifying patients with unexpected bleeding phenotype was investigated. METHODS: Overall hemostasis potential (OHP), aPTT-clot waveform analysis (aPTT-CWA), endogenous thrombin potential (ETP), FVIII activities, and prothrombin fragment 1 + 2 concentrations were measured in 62 HA patients (30 severe and 32 non-severe) and 27 male controls. Bleeding phenotype was determined using our proposed scoring system including age at first joint bleed, number of target joints, and number of joint/muscle bleeds per year. Bleeding score ≤ 4 defined patients with mild bleeding phenotype (N = 27); score ≥ 5 defined severe bleeding phenotype (N = 35). RESULTS: The receiver operating characteristic analysis performed for distinguishing patients with severe and mild bleeding phenotype yielded following values of area under the curve: 0.910 (FVIII); 0.891 (aPTT-CWA parameter DELTA); 0.769 (OHP); and 0.634 (ETP). Unexpected bleeding phenotype was identified in 11/62 HA patients: 8/32 (25%) non-severe HA patients had severe, while 3/30 (10%) severe HA patients had mild bleeding phenotype, and global assays enabled the identification of all these patients. OHP and DELTA were revealed as the most reliable parameters for bleeding phenotype determination (10/11 and 9/11 unexpected results, respectively). CONCLUSION: This study emphasizes OHP and aPTT-CWA as a powerful laboratory diagnostic tool in identifying HA patients with unexpected bleeding presentations, with the best results achieved by combining both assays. Global assays should not completely replace FVIII activity measurement but should be a part of the HA diagnostic algorithm.

Non-phthalate plasticizer DEHT preserves adequate blood component quality during storage in PVC blood bags.

BACKGROUND AND OBJECTIVES: Commercial blood bags are predominantly made of polyvinyl chloride (PVC) plasticized with di(2-ethylhexyl) phthalate (DEHP). DEHP is favourable for storage of red blood cells (RBC). Historically, removal of DEHP from blood bags has been linked to unacceptable haemolysis levels. Oncoming regulatory restrictions for DEHP due to toxicity concerns increase the urgency to replace DEHP without compromising RBC quality. Di(2-ethylhexyl) terephthalate (DEHT) is one suggested substitute. The aim of this study was to compare PVC-DEHT to PVC-DEHP blood bags using additive solutions saline-adenine-glucose-mannitol (SAGM) and phosphate-adenine-glucose-guanosine-saline-mannitol (PAGGSM), to determine whether DEHT can maintain acceptable component quality. MATERIALS AND METHODS: RBC concentrates (N = 64), platelet concentrates (N = 16) and fresh frozen plasma (N = 32) were produced from whole blood collected into either DEHT or DEHP plasticized systems. Using a pool-and-split study design, pairs of identical RBC content were created within each plasticizer arm and assigned either SAGM or PAGGSM. Storage effects were assessed weekly for 49 days (RBC), 7 days (platelets) and before/after freezing (plasma). RESULTS: Though haemolysis was slightly higher in DEHT, all study arms remained below half of the European limit 0·8%. K+ was lower in DEHT than in DEHP independent of additive solution. The metabolic parameters were not influenced by choice of plasticizer. Platelet activation/metabolism and plasma content were similarly preserved. CONCLUSION: Our study demonstrates that the plasticizer DEHT provides adequate blood component quality. We propose DEHT as a strong future candidate for replacement of DEHP in blood bags.