Association of ABO blood group with bleeding severity in patients with bleeding of unknown cause

Examining variability in the diagnosis and management of people with bleeding disorders of unknown cause: communication from the ISTH SSC Subcommittee on von Willebrand Factor

BACKGROUND

Bleeding disorder of unknown cause (BDUC) is characterized by a bleeding phenotype in the setting of normal hemostatic testing. No standardized diagnostic criteria or treatment algorithms exist for people with BDUC. To address the unmet need, the International Society on Thrombosis and Haemostasis von Willebrand Factor Scientific Subcommittee performed a real-world survey aimed at addressing knowledge gaps, developing consensus pathways, and ultimately improving care.

OBJECTIVES

We sought to determine current international clinical practices in the investigation, registration, and treatment of people with BDUC internationally.

METHODS

An online structured survey was conducted of healthcare providers who managed patients with bleeding disorders using the ISTH RedCap tool.

RESULTS

Two hundred sixteen respondents from 39 countries were included in the final analysis. The clinical assessment of those with a possible bleeding disorder varied, with only 55% excluding hypermobility but high levels (80%) of bleeding assessment tool usage. In hemostatic testing, only the prothrombin time and activated partial thromboplastin time tests gained universal support. Tranexamic acid was favored for prophylaxis for minor (71%)/major (59%) surgeries and pregnancy (58%), but advice on the treatment if bleeding occurred was heterogeneous. The management of heavy menstrual bleeding in women despite combined oral contraceptive pill use also proved challenging, with healthcare providers selecting multiple alternative strategies.

CONCLUSION

Significant variation exists in the recognition, registration, and management of people with BDUC worldwide. This survey emphasizes the need for consensus pathways to diagnose and treat BDUC to standardize and improve care for patients internationally.

Bleeding Disorder of Unknown Cause: A Diagnosis of Exclusion

Patients with an unexplained mild to moderate bleeding tendency are diagnosed with bleeding disorder of unknown cause (BDUC), a classification reached after ruling out other mild to moderate bleeding disorders (MBD) including von Willebrand disease (VWD), platelet function defects (PFDs), coagulation factor deficiencies (CFDs), and non-hemostatic causes for bleeding. This review outlines our diagnostic approach to BDUC, a diagnosis of exclusion, drawing on current guidelines and insights from the Vienna Bleeding Biobank (VIBB). According to guidelines, we diagnose VWD based on VWF antigen and/or activity levels ≤50 IU/dL, with repeated VWF testing if VWF levels are <80 IU/dL. This has been introduced in our clinical routine after our findings of diagnostically relevant fluctuations of VWF levels in a high proportion of MBD patients. PFDs are identified through repeated abnormalities in light transmission aggregometry (LTA), flow cytometric mepacrine fluorescence, and glycoprotein expression analysis. Nevertheless, we experience diagnostic challenges with regard to reproducibility and unspecific alterations of LTA. For factor (F) VIII and FIX deficiency, a cutoff of 50% is utilized to ensure detection of mild hemophilia A or B. We apply established cutoffs for other rare CFD being aware that these do not clearly reflect the causal role of the bleeding tendency. Investigations into very rare bleeding disorders due to hyperfibrinolysis or increase in natural anticoagulants are limited to cases with a notable family history or distinct bleeding phenotypes considering cost-effectiveness. While the pathogenesis of BDUC remains unknown, further explorations of this intriguing area may reveal new mechanisms and therapeutic targets.

Standardization of definition and management for bleeding disorder of unknown cause: communication from the SSC of the ISTH

In many patients referred with significant bleeding phenotype, laboratory testing fails to define any hemostatic abnormalities. Clinical practice with respect to diagnosis and management of this patient cohort poses significant clinical challenges. We recommend that bleeding history in these patients should be objectively assessed using the International Society on Thrombosis and Haemostasis (ISTH) bleeding assessment tool. Patients with increased bleeding assessment tool scores should progress to hemostasis laboratory testing. To diagnose bleeding disorder of unknown cause (BDUC), normal complete blood count, prothrombin time, activated partial thromboplastin time, thrombin time, von Willebrand factor antigen, von Willebrand factor function, coagulation factors VIII, IX, and XI, and platelet light transmission aggregometry should be the minimum laboratory assessment. In some laboratories, additional specialized hemostasis testing may be performed to identify other rare causes of bleeding. We recommend that patients with a significant bleeding phenotype but normal laboratory investigations should be registered with a diagnosis of BDUC in preference to other terminology. Global hemostatic tests and markers of fibrinolysis demonstrate variable abnormalities, and their clinical significance remains uncertain. Targeted genomic sequencing examining candidate hemostatic genes has a low diagnostic yield. Underlying BDUC should be considered in patients with heavy menstrual bleeding since delays in diagnosis often extend to many years and negatively impact quality of life. Treatment options for BDUC patients include tranexamic acid, desmopressin, and platelet transfusions.

Activated protein C and free protein S in patients with mild to moderate bleeding disorders

BACKGROUND

Underlying mechanisms for bleeding and impaired thrombin generation (TG) and plasma clot formation (PCF) in patients with mild to moderate bleeding disorders (MBDs) are still to be elucidated, especially in bleeding disorder of unknown cause (BDUC). The role of the natural anticoagulants activated protein C (APC) and free protein S (PS) has not yet been investigated in this patient population.

AIMS

To analyze antigen levels of APC and PS in patients with MBDs and BDUC and investigate associations to clinical bleeding phenotype and severity as well as and hemostatic capacity.

METHODS

Antigen levels of APC and free PS were measured in 262 patients from the Vienna Bleeding Biobank (VIBB), a single-center cohort study, by ELISA and compared to 61 healthy controls (HC).

RESULTS

Antigen levels of APC were higher in MBD patients than in HC when adjusted for age, sex and BMI (median (IQR) 33.1 (20.6-52.6) and 28.6 (16.4-47.2) ng/mL). This was most pronounced in patients with BDUC (35.3 (21.7-54.3) ng/mL). No differences in PS antigen levels between patients and HC were seen overall, or according to specific diagnoses. Further, no association between APC or PS and bleeding severity or global tests of hemostasis or TG were identified, while paradoxically APC weakly correlated with shorter lag time and time to peak of PCF in BDUC.

CONCLUSION

Our data demonstrate increased antigen levels of APC in BDUC, which might contribute to the bleeding tendency in some patients and could be a future therapeutic target in BDUC.

Impact of Additional Administration of von Willebrand Factor Concentrates to Thrombocyte Transfusion in Perioperative Bleeding in Cardiac Surgery

Background

Von Willebrand factor (vWF) is an important part of blood coagulation since it binds platelets to each other and to endothelial cells. In traumatic and surgical haemorrhage, both blood cells and plasmatic factors are consumed, leading to consumption coagulopathy and fluid resuscitation. This often results in large amounts of crystalloids and blood products being infused. Additional administration of vWF complex and platelets might mitigate this problem. We hypothesize that administration of vWF concentrate additionally to platelet concentrates reduces blood loss and the amount of blood products (platelets, red blood cells [RBC], fresh frozen plasma [FFP]) administered.

Methods

We conducted a monocentric 6-year retrospective data analysis of cardiac surgery patients. Included were all patients receiving platelet concentrates within 48 h postoperatively. Patients who additionally received vWF concentrates were allocated to the intervention group and all others to the control group. Groups were compared in mixed regression models correcting for known confounders, based on nearest neighbour propensity score matching. Primary endpoints were loss of blood (day one and two) and amount of needed blood products on day one and two (platelets, RBC, FFP). Secondary endpoints were intensive care unit (ICU) and in-hospital length of stay, ICU and in-hospital mortality, and absolute difference of platelet counts before and after treatment.

Results

Of 497 patients analysed, 168 (34%) received vWF concentrates. 121 patients in both groups were considered for nearest neighbour matching. Patients receiving additional vWF were more likely to receive more blood products (RBC, FFP, platelets) in the first 24 h after surgery and had around 200 mL more blood loss at the same time.

Conclusion

In this retrospective analysis, no benefit in additional administration of vWF to platelet concentrates on perioperative blood loss, transfusion requirement (platelets, RBC, FFP), length of stay, and mortality could be found. These findings should be verified in a prospective randomized controlled clinical trial (www.clinicaltrials.gov identifier NCT04555785).

The necessity of repeat testing for von Willebrand disease in adult patients with mild to moderate bleeding disorders

BACKGROUND

In patients with mild-to-moderate bleeding disorders (MBD), von Willebrand disease (VWD) is diagnosed at von Willebrand factor (VWF) levels ≤50 IU/dL. Although VWF levels are unstable, repeated testing for VWD diagnosis is not necessarily advised in recent guidelines.

OBJECTIVES

To analyze the relevance of repeated VWF testing to diagnose VWD in patients with MBD.

METHODS

Data of 277 patients with MBD from the Vienna Bleeding Biobank with at least 2 separate assessments of VWF antigen (VWF:Ag) and activity (VWF:Act) were analyzed.

RESULTS

In repeated VWF measurements, 36 patients (13.0%) had "changing" VWF levels (≤/>50 IU/dL), 27 (9.7%) had persistent levels ≤50 IU/dL ("pathologic"), and 214 (77.3%) had levels >50 IU/dL ("normal"). Of the 36 changing patients, 22 (61%) were diagnosed with VWD at baseline, whereas the others only met VWD diagnostic criteria at repeated measurements. Using logistic regression, we estimated a probability of change of 26.4% (95% CI, 12.5-47.4) at baseline VWF levels of 30 IU/dL, 50.8% (95% CI, 35.6-65.8) at 50 IU/dL, 18.8% (95% CI, 12.3-27.6) at 60 IU/dL, and 1.2% (95% CI, 0.3-4.9) at 80 IU/dL. Baseline VWF was a strong predictor for changing status (Χ2 = 49.9; P < .001), while age, sex, Vicenza score, and blood type O had limited added value (Χ2 = 5.1; P = .278). Baseline VWF:Ag or VWF:Act cutoffs of 80 IU/dL had negative predictive values of 98.1% and 99.1% for changing status, respectively.

CONCLUSION

Our data emphasize an overlap between patients with VWD and MBD with bleeding disorder of unknown cause and underline the need for repeated VWF testing, especially in patients with VWF levels <80 IU/dL.

Investigating patients for bleeding disorders when most of the "usual" ones have been ruled out

A State of the Art lecture titled "Investigating Patients for Bleeding Disorders When Most of the Usual Ones Have Been Ruled Out" was presented at the International Society on Thrombosis and Haemostasis Congress in 2023. Mild to moderate bleeding disorders (MBDs) in patients in whom no diagnosis of an established disorder, such as platelet function defect, von Willebrand disease, or a coagulation factor deficiency, can be identified are classified as bleeding disorders of unknown cause (BDUCs). Prospective data from the Vienna Bleeding Biobank and other studies have revealed a high proportion of BDUCs of up to 70% among patients with MBD who have a similar bleeding phenotype as other MBDs. As BDUC is a diagnosis of exclusion, the accuracy of the diagnostic workup is essential. For example, repeated testing for von Willebrand disease should be considered if von Willebrand factor values are <80 IU/dL. Current evidence does not support the clinical use of global assays such as thromboelastography, platelet function analyzer, or thrombin generation potential. Rare and novel bleeding disorders due to genetic variants in fibrinolytic factors or natural anticoagulants are rare and should only be analyzed in patients with specific phenotypes and a clear family history. In BDUC, blood group O was identified as a risk factor for increased bleeding severity and bleeding risk after hemostatic challenges. Future studies should improve the phenotypical characterization and ideally identify novel risk factors in BDUC, as a multifactorial pathogenesis is suspected. Finally, we summarize relevant new data on this topic presented during the 2023 International Society on Thrombosis and Haemostasis Congress.

Thrombophilia gene mutations predict venous thromboembolism in ambulatory cancer patients receiving chemotherapy

BACKGROUND

Inherited thrombophilia and cancer both independently increase the risk of venous thromboembolism (VTE). However, whether the increased VTE risk associated with inherited thrombophilia exists in cancer patients is less clear.

OBJECTIVES

Our objective was to determine the influence of inherited thrombophilia on VTE and bleeding risk in moderate-to-high-risk ambulatory cancer patients receiving chemotherapy.

METHODS

We conducted a post hoc analysis using blood samples from patients enrolled in the AVERT trial to determine if previously recognized thrombophilia gene mutations (prothrombin factor [F] II G20210A, FXI, fibrinogen gamma, serpin family A member 10, FV K858R, FXIII, FV Leiden [FVL], and ABO blood) were associated with VTE or bleeding during the 7-months after starting chemotherapy. Logistic regression was used to compare heterozygous and homozygous mutations (combined) to wild-type. VTE rates, bleeding rates, and risk differences for mutations stratified by prophylactic anticoagulation use were calculated.

RESULTS

Of the 447 patients, there were 39 VTE and 39 bleeding events. The odds of VTE were significantly increased with FVL mutation and non-O blood type (odds ratio [OR]: 5.2; 95% CI: 1.9-14.7 and OR: 2.7; 95% CI: 1.2-6.1, respectively). The use of anticoagulation prophylaxis resulted in complete protection in FVL patients, whereas those not receiving anticoagulation had a VTE rate of 119 per 100 patient-years. Lower VTE rates were also observed in non-O blood type patients taking prophylactic anticoagulation. No other thrombophilia genes tested were significantly associated with VTE or bleeding.

CONCLUSION

Our results indicate that FVL mutation and ABO blood type may be important VTE predictors in cancer patients starting chemotherapy.

Bleeding disorder of unknown cause: Results from Iranian study

BACKGROUND

Definite diagnosis of patients with mild to moderate bleeding is challenging. Some studies reported that even more than 50% of their patients remained undiagnosed which is classified as a Bleeding disorder of unknown cause (BDUC). This study aims to document the clinical characteristics and proportion of patients with BDUC in the Iranian Comprehensive Hemophilia Care Center (ICHCC) one of the referral centers for diagnosis of congenital bleeding disorder in Iran.

METHODS

This study was conducted on 397 patients who were referred with a bleeding manifestation to ICHCC from 2019 to 2022. Demographic and laboratory data were documented for all patients. Bleeding questionnaires including ISTH-Bleeding Assessment tool (ISTH-BAT) and the Molecular and Clinical Markers for the Diagnosis and Management of Type 1 (MCMDM-1 (ISTH-BAT, MCMDM-1, and the Pictorial Bleeding Assessment Chart (PBLAC) were filled out for all patients. The data were analyzed by the statistical package for social science (SPSS version 22, SPSS, Chicago, Illinois, USA).

RESULTS

BDUC was diagnosed in 200 patients and 197 patients reached the final diagnosis. Hemophilia, von Willebrand disease (VWD), factor (F) VII deficiency, and platelet functional disorders (PFDs) were confirmed in 54, 49, 34, and 15 of the patients, respectively. No significant difference was found in bleeding scores between patients with BDUC and those with confirmed disease. In contrast, after setting cut-off (ISTH-BAT for males ≥ 4 and females ≥ 6 and MCMDM-1 for males ≥ 3 and females ≥ 5) clinically significant difference was found. There was no association between having a positive consanguineous marriage and setting a diagnosis; however, significant associations were seen for having a positive family history of bleeding. Age (OR =0.977, 95% CI.965-0.989), gender (BDUC female, 151/200; final diagnosis female, 95/197) (OR=3.3, 95% CI 2.16-5.06), family history (OR = 3.19, 95% CI 1.99-5.11), and consanguineous marriage (OR=1.59, 95% CI 1.03-2.45) were considered as a risk factor for categorizing the patients with BDUC or final diagnosis.

CONCLUSION

The findings are mainly in line with previous studies about BDUC patients. The large number of patients with BDUC underlines the incompleteness of available routine laboratory tests and shows the necessity of progress in the development of reliable diagnostic tools to identify underlying bleeding disorders.

Evaluation of Clinical Manifestations of Hemorrhoidal Disease, Carried Out Surgeries and Prolapsed Anorectal Tissues: Associations with ABO Blood Groups of Patients

Hemorrhoidal disease (HD) is a chronic multifactorial disease. Increased abdominal pressure, along with hyperperfusion, neovascularization, overexpression of inflammatory mediators, and dysbiosis, contributes to the development of HD. The deterioration of the anchoring connective tissue with reduced collagen content and altered collagen ratios, dilatation of blood vessels and thrombosis, muscle injury, and inflammation gradually lead to clinically manifesting prolapse and bleeding from hemorrhoids. The associations of the ABO blood types with a disease have been investigated for the upper gastrointestinal tract only. This study aimed to evaluate HD clinical manifestations, surgeries carried out, and the status of prolapsed anorectal tissues by exploring the associations with the patients' ABO blood groups. Clinical and various morphological methods, combined with extensive bioinformatics, were used. The blood type 0, grade III and IV HD individuals constituted the largest group in a moderately-sized cohort of equally represented males and females studied and submitted to surgical treatment of hemorrhoids. There were significantly more complaints reported by HD females compared to males (p = 0.0094). The Longo technique appeared mostly used, and there were proportionally more surgeries performed below the dentate line for HD individuals with blood type 0 compared to other blood type patients (24% vs. 11%). HD males were found to present with significantly more often inflamed rectal mucosa (p < 0.05). Loosening and weakening of collagenous components of the rectal wall combined with vascular dilation and hemorrhage was found to differ in 0 blood type HD individuals compared to other types. HD males were demonstrated to develop the ruptures of vascular beds significantly more often when compared to HD females (p = 0.0165). Furthermore, 0 blood type HD males were significantly more often affected by a disease manifested with tissue hemorrhage compared to the 0 blood type HD females (p = 0.0081). Collectively, the local status of chronically injured anorectal tissue should be considered when applying surgical techniques. Future studies could include patients with HD grades I and II to gain a comprehensive understanding of the disease progression, allowing for a comparison of tissue changes at different disease stages.

Health-related quality of life is impaired in bleeding disorders of unknown cause: results from the Vienna Bleeding Biobank

Background

Bleeding disorder of unknown cause (BDUC) is a diagnosis of exclusion after extensive investigation of coagulation and platelet function and is commonly seen among patients with mild-to-moderate bleeding disorders. Despite increasing awareness among treating physicians, little is known about the health-related quality of life (HrQoL) in BDUC.

Objectives

To investigate HrQoL in patients with BDUC in comparison to the general population and patients diagnosed with other established bleeding disorders.

Methods

Patients with mild-to-moderate bleeding disorders from the Vienna Bleeding Biobank, a prospective cohort study, were contacted via mail and phone to complete the 36-Item Health Survey Questionnaire form.

Results

In total, 333/657 (50.7%) patients completed the 36-Item Health Survey Questionnaire. Patients with BDUC (n = 207, 62%) had significantly impaired HrQoL both in physical (47.8 vs 49.2) and mental health parameters (42.9 vs 51.0) compared to the general population (n = 2914, 56% females), which remained after adjustment for sex and age in multivariable linear regression. The impairment in HrQoL, compared to patients with von Willebrand disease, platelet function defects, or mild clotting factor deficiencies, did not prevail after adjustment for age and sex. In patients with BDUC, age and the presence of at least 1 comorbidity were associated with impaired physical health but not sex or bleeding severity. Of all analyzed bleeding symptoms, only joint bleeding was associated with impaired physical health and gastrointestinal bleeding with mental health in BDUC.

Conclusion

The impairments in HrQoL in patients with BDUC emphasize the burden of BDUC on mental and physical well-being, encouraging early recognition and better counseling of patients with BDUC.

Risk factors for future bleeding in patients with mild bleeding disorders: longitudinal data from the Vienna Bleeding Biobank

BACKGROUND

The future bleeding risk, especially after hemostatic challenges, and thus the requirement for hemostatic treatment in patients with mild-to-moderate bleeding disorders (MBDs) is largely unknown.

OBJECTIVES

This study aimed to prospectively examine the recurrence of bleeding symptoms and clinical risk factors for future bleeding in patients with MBD, including patients with bleeding disorder of unknown cause (BDUC).

METHODS

Bleeding symptoms of patients with MBD included in the Vienna Bleeding Biobank were re-evaluated at in-person follow-up visits or by mail.

RESULTS

In total, 392 patients, including 62.8% with BDUC, were investigated for the recurrence of bleeding events. During the follow-up time of median (IQR) 4.3 years (2.6-6.7), 72% of patients had at least 1 bleeding event. Most persistent bleeding manifestations were hematomas (n = 146/245, 59.6%) and bleeding from small wounds (n = 69/141, 48.9%), followed by epistaxis (n = 42/132, 31.8%), oral mucosal bleeding (n = 26/87, 29.9%), and joint bleeding (n = 7/14, 50.0%). Patients with previous postinterventional bleeding had a significantly increased risk for bleeding events after surgery (n = 33/114, 29.0 %) or tooth extraction (n = 16/39, 41.0%). A high bleeding score (OR [95% CI], 1.14 [1.05 to 2.94], per 1 unit) and follow-up time (OR [95% CI], 1.23 [1.12 to 1.36], per 1 year) were independently associated with any bleeding event. For bleeding after hemostatic challenges, blood group O (OR, 3.17 [1.57 to 6.40]), previous postsurgical bleeding (OR, 2.40 [1.06 to 5.46]), and an established diagnosis (OR, 2.07 [1.04 to 4.10]) were independent risk factors.

CONCLUSION

Patients with MBD have a high risk for recurrent bleeding. This encourages prophylactic hemostatic treatment in patients with MBD, particularly when they face hemostatic challenges.

Correlation between Blood Type 0 and Risk of Chronic Subdural Hematoma Recurrence: A Single Center Retrospective Cohort Study

Chronic subdural hematoma (cSDH) is a common disease in the neurological and neurosurgical world. The recommended treatment for cSDH patients with moderate or severe neurological symptoms is surgical evacuation, but cSDH frequently recurs. The patient’s ABO blood type may influence the outcome. This study aims to evaluate the correlation between cSDH recurrence and blood type O. We performed a retrospective analysis of the data of patients with cSDH who were surgically treated. Recurrence was defined as the need for re-operation within the first 12 weeks after the initial surgery. We analyzed standard demographic data, duration and type of surgery, ABO blood types, and the re-operation rate. Univariate and multivariate analyses were conducted. A total of 229 patients were included. The recurrence of hematoma was identified in 20.5% of patients. Blood type O was found to be significantly associated with cSDH recurrence leading to re-operation within 12 weeks (p = 0.02, OR 1.9, 95% CI 1.1–3.5). Thrombocyte aggregation inhibition and oral anticoagulants were not predictors of cSDH recurrence. Patients with blood type O in our cohort were identified to be at higher risk of cSDH recurrence and may, therefore, be a more vulnerable patient group. This finding needs further evaluation in larger cohorts.

Clinical Predictors and Prediction Models for rFVIII-Fc Half Life in Real-World People with Severe Hemophilia A

The half life of recombinant factor VIII-Fc (rFVIII-Fc) for people with hemophilia A (PwHA) varies greatly. Understanding the factors influencing the variation and assessment of rFVIII-Fc half life is important for personalized treatment. Eighty-five severe-type PwHA with rFVIII-Fc treatment receiving an evaluation of half life by the Web-Accessible Population Pharmacokinetic (PK) Service—Hemophilia during 2019–2021 were retrospectively enrolled. The 50-patient PK profiles before 2021 were used for analysis and developing prediction models of half life, and the 35-patient PK profiles in 2021 were used for external validation. The patients in the development cohort were aged 8–64, with a median rFVIII-Fc half life of 20.75 h (range, 8.25–41.5 h). By multivariate linear regression analysis, we found two, four, and five predictors of rFVIII-Fc half life for the blood groups non-O, O patients, and overall patients, respectively, including VWF:Ag, BMI, VWF:activity/VWF:Ag ratio, body weight, O blood group, inhibitor history, HCV infection, and hematocrit. The three prediction equations of rFVIII-Fc half life (T) were respectively developed as T for non-O group patients = −0.81 + 0.63 × (BMI, kg/m2) + 6.07 × (baseline VWF:Ag, IU/mL), T for O group patients = −0.68 + 13.30 × (baseline VWF:Ag, IU/mL) + 0.27 × (BW, kg) − 1.17 × (BMI, kg/m2) + 16.02 × (VWF:activity/VWF:Ag ratio), and T for overall patients = −1.76 + 7.24 × (baseline VWF:Ag, IU/mL) − 3.84 × (Inhibitor history) + 2.99 × (HCV infection) − 2.83 × (O blood group) + 0.30 × (Hct, %), which explained 51.97%, 75.17%, and 66.38% of the half life variability, respectively. For external validation, there was a significant correlation between the predicted and observed half lives in the validation cohort. The median half life deviation was +1.53 h, +1.28 h, and +1.79 h for the equations of non-O group, O group, and overall group patients, respectively. In total, eight predictors influencing rFVIII-Fc half life were identified. Prediction equations of rFVIII-Fc half life were developed for the non-O and O blood groups and overall PwHA with a good degree of external validation. The equations could be applied to patients aged 8–64 without the need for PK blood sampling and clinically valuable for personalized therapy.

Risk factors for 30-day postoperative surgical site hematoma requiring evacuation after resection of brain metastases

OBJECTIVE

To identify the risk factors for a 30-day postoperative surgical site hematoma requiring evacuation (POH) after surgical resection of brain metastases.

METHODS

Patients who underwent surgical resection of brain metastases between 2011 and 2019 at our institution were included. Risk factors for a 30-day POH were identified using a multivariate logistic regression model.

RESULTS

A total of 158 patients were included in the analysis. The mean (SD) age of the study population was 59.3 (12.0) years, and 82 (53.2%) patients were female. The incidence of a 30-day POH was 8.2% (13 patients). There was no statistically significant association between the occurrence of a 30-day POH and overall mortality (p = 0.100). On multivariate analysis, there was a statistically significant association between a 30-day POH and younger age (OR=0.91; 95% CI=0.83, 0.99; p = 0.035), higher BMI (OR=1.61; 95% CI=1.16, 2.46; p = 0.010), and blood type AB (OR=21.7; 95% CI=1.66, 522; p = 0.031). On receiver operating characteristic analysis, a threshold BMI of 25.1 kg/m² and threshold age of 57 gave the optimum balance of sensitivity and specificity in predicting the occurrence of a 30-day POH.

CONCLUSIONS

Patients below 57 years old, who have a BMI of above 25, and/or have blood type AB were at higher risk of developing a 30-day POH after surgical resection of brain metastases. Additional care in intraoperative hemostasis and postoperative monitoring may be indicated among patients who have these risk factors.

Impact of ABO Blood Group on Thromboembolic and Bleeding Complications in Patients with Left Ventricular Assist Devices

BACKGROUND

 The ABO blood group system is linked to hemostasis via its relationship with von Willebrand factor (VWF) and factor VIII (FVIII). In the current study, we investigated the association of the ABO system with clinical outcomes as well as VWF and platelet function in patients with left ventricular assist devices (LVADs).

METHODS

 Bleeding and thromboembolic complications were assessed in 111 patients during 1 year after LVAD implantation. In 67 LVAD patients, VWF antigen, VWF activity, VWF ristocetin cofactor, VWF collagen-binding, and FVIII activity were assessed. Platelet surface P-selectin and activated glycoprotein IIb/IIIa were determined by flow cytometry, and soluble P-selectin was measured with an enzyme-linked immunoassay. Platelet aggregation was assessed by light transmission and impedance aggregometry.

RESULTS

 Thirty-six patients (32.4%) experienced a bleeding and 22 patients (19.8%) a thromboembolic event. In univariate analyses, patients with blood group O had numerically more bleeding complications and less thromboembolic events as compared to patients with blood group non-O (both p ≥ 0.05). After multivariable adjustment, blood group O was significantly associated with a higher risk of bleeding (hazard ratio 2.42 [95% confidence interval 1.03-5.70], p = 0.044) but not linked to thromboembolic complications.

CONCLUSION

 Patients with blood group O had significantly lower levels of VWF and FVIII (all p < 0.05), whereas P-selectin expression in response to thrombin-receptor activating peptide and soluble P-selectin were higher as compared to patients with blood group non-O (both p < 0.05). LVAD patients with blood group O are at an increased bleeding risk, potentially due to lower VWF and FVIII levels.

Platelet function and soluble P-selectin in patients with primary immune thrombocytopenia

BACKGROUND

The bleeding phenotype in immune thrombocytopenia (ITP) is heterogeneous, but usually mild and only partly dependent on the severity of thrombocytopenia. Platelet reactivity has previously been suggested to underly the mild phenotype.

METHODS

Platelet function was assessed as basal and agonist-induced surface expression of P-selectin and activation of GPIIb/IIIa via flow cytometry, and soluble (s)P-selectin levels were assessed in plasma of 77 patients with primary ITP, 19 hemato-oncologic thrombocytopenic controls (TC) and 20 healthy controls (HC). The association of platelet function with laboratory and clinical parameters such as bleeding manifestations at inclusion and previous thrombosis was analyzed.

RESULTS

ITP patients showed tendency towards increased surface P-selectin and elevated levels of activated GPIIb/IIIa. Platelet activation after stimulation with all agonists including TRAP-6, ADP, arachidonic acid and CRP was decreased compared to HC. Compared to TC, only GPIIb/IIIa activation but not surface P-selectin was higher in ITP. Levels of soluble (s)P-selectin were significantly higher in ITP patients compared to TC, but similar to HC. Higher sP-selectin levels were associated with blood group O and current therapy, with highest levels in TPO-RA treated patients. Platelet reactivity was not associated with platelet count or size, platelet antibodies, treatment regime, or blood group. No correlation between platelet activation with the bleeding phenotype or previous thrombotic events could be observed.

CONCLUSION

ITP patients did not have hyper-reactive platelets compared to HC, but partly higher reactivity compared to TC. Further studies are needed to understand the underlying mechanism behind the bleeding and pro-thrombotic phenotype in ITP. 250/250.

Tissue factor pathway inhibitor is a potential modifier of bleeding risk in factor XI deficiency

BACKGROUND

Factor (F) XI deficiency is associated with increased bleeding risk in some individuals. Neither FXI levels nor clinical clotting assays predict the bleeding risk. Compared with controls, FXI-deficient bleeders have reduced clot formation, decreased fibrin network density, and increased susceptibility to fibrinolysis. Tissue factor pathway inhibitor (TFPI) was recently implicated as a modifying factor in individuals with bleeding of unknown cause.

OBJECTIVES

To determine the potential of TFPI in modifying the bleeding risk in FXI-deficient individuals.

METHODS

The effects of TFPI on thrombin generation and clot formation, structure, and fibrinolysis in FXI-deficient plasma were measured in vitro in the absence or presence of inhibitory anti-TFPI antibody or exogenous recombinant TFPIα. Total plasma TFPI concentration was measured in 2 independent cohorts of controls and FXI-deficient individuals classified as bleeders or nonbleeders (cohort 1: 10 controls and 16 FXI-deficient individuals; cohort 2: 48 controls and 57 FXI-deficient individuals) and correlated with ex vivo plasma clot formation and fibrinolysis parameters associated with bleeding risk.

RESULTS

In an in vitro FXI deficiency model, inhibition of TFPI enhanced thrombin generation and clot formation, increased the network density, and decreased fibrinolysis, whereas an increase in TFPI had the opposite effects. Compared with controls, plasma from FXI-deficient bleeders had higher TFPI concentration. Total plasma TFPI concentrations correlated with parameters from ex vivo clotting and fibrinolysis assays that differentiate FXI-deficient bleeders and nonbleeders.

CONCLUSION

Coagulation and fibrinolysis parameters that differentiate FXI-deficient nonbleeders and bleeders were altered by plasma TFPIα. Total plasma TFPI was increased in FXI-deficient bleeders. TFPI may modify the bleeding risk in FXI-deficient individuals.

ABO blood group antigens and differential glycan expression: Perspective on the evolution of common human enzyme deficiencies

Enzymes catalyze biochemical reactions and play critical roles in human health and disease. Enzyme variants and deficiencies can lead to variable expression of glycans, which can affect physiology, influence predilection for disease, and/or directly contribute to disease pathogenesis. Although certain well-characterized enzyme deficiencies result in overt disease, some of the most common enzyme deficiencies in humans form the basis of blood groups. These carbohydrate blood groups impact fundamental areas of clinical medicine, including the risk of infection and severity of infectious disease, bleeding risk, transfusion medicine, and tissue/organ transplantation. In this review, we examine the enzymes responsible for carbohydrate-based blood group antigen biosynthesis and their expression within the human population. We also consider the evolutionary selective pressures, e.g. malaria, that may account for the variation in carbohydrate structures and the implications of this biology for human disease.

Platelet Dysfunction in Blood Donors Detected by Platelet Function Analyzer PFA-100™

Background

Platelet transfusions may be indicated to prevent and treat bleeding in patients with quantitative or qualitative platelet defects. Millions of platelet components are transfused worldwide. It is well known that platelet dysfunction predicts blood loss after surgery. Hence, the quality of the platelet donation and the resulting platelet concentrate are critical for the transfusion. The aim of this study is to assess platelet function in well-qualified blood donors.

Methodology

Blood samples from 275 blood donors were collected in 0.129 M (3.8%) sodium citrate tubes prior to routine blood donation. Platelet function was assessed by measuring the closure time (CT) on the platelet function analyzer (PFA-100™; Siemens Health Diagnostics, Marburg, Germany) using collagen/epinephrine (CEPI) and collagen/ADP (CDP) cartridges.

Results

Using the PFA-100™, 20.4% of donors had an abnormal platelet function test, of whom 9.4% had prolonged CT with two cartridges, 7% had only prolonged CEPI CTs consistent with aspirin-like defect, and 4% had prolonged CADP CTs only. We found no closure (>300 seconds) in 6.54% of donors, including 1.45% with the CEPI cartridge, 2.9% with the CADP cartridge, and 2.18% with CEPI and CADP cartridges. Level of von Willebrand factor ristocetin cofactor (vWF: RCo) activity was 112% (56-168%). Of the factors examined (age, sex, cigarette smoking, blood donation type, ABO, and Rhesus blood group), only blood group O was significantly linked with impaired platelet function test in qualified blood donors (p = 0.023; odds ratio = 1.981; 95% confidence interval (1.091-3.595)).

Conclusions

Some qualified blood donors present abnormal platelet function results. More research is required to provide greater insight into the impact of platelet dysfunction in blood donors on the clinical efficacy of their platelet components. This study has confirmed that the influence of ABO blood group on the CT PFA-100™is not wholly dependent on vWF.

An Investigation of ABO Blood Type and the Platelet Delta Granule Storage Pool

Individuals with bleeding tendencies are more likely to have blood type O than blood types A, B, or AB. Platelet storage pool deficiencies are a lesser-known group of bleeding disorders which often go undiagnosed and may account for a significant number of patients with unexplained bleeding defects. We hypothesized that patients with platelet δ-storage pool deficiency might also have a predominance of type O blood. A retrospective review of medical records of 2,020 patients with unexplained bleeding and evaluated for δ-storage pool deficiency was performed. Correlations between dense granule numbers, blood type, and von Willebrand factor were analyzed for statistical differences. 51.5% of blood samples were blood type O compared to an incidence of 44.0% in the U.S. population. There was a significant association of vWF and blood type O but not with the delta storage pool. There is a preponderance of blood type O in the study population compared to the U.S. population. There is no statistically significant link between blood type O and lower dense granule numbers in this study.

Thrombomodulin in patients with mild to moderate bleeding tendency

Introduction

A massive increase of soluble thrombomodulin (sTM) due to variants in the thrombomodulin gene (THBD) has recently been identified as a novel bleeding disorder.

Aim

To investigate sTM levels and underlying genetic variants as a cause for haemostatic impairment and bleeding in a large number of patients with a mild to moderate bleeding disorder (MBD), including patients with bleeding of unknown cause (BUC).

Patients and methods

In 507 MBD patients, sTM levels, thrombin generation and plasma clot formation were measured and compared to 90 age‐ and sex‐matched healthy controls. In patients, genetic analysis of the THBD gene was performed.

Results

No difference in sTM levels between patients and controls was found overall (median ([IQR] 5.0 [3.8‐6.3] vs. 5.1 [3.7‐6.4] ng/ml, p = .762), and according to specific diagnoses of MBD or BUC, and high sTM levels (≥95th percentile of healthy controls) were not overrepresented in patients. Soluble TM levels had no impact on bleeding severity or global tests of haemostasis, including thrombin generation or plasma clot formation. In the THBD gene, no known pathogenic or novel disease‐causing variants affecting sTM plasma levels were identified in our patient cohort.

Conclusion

TM‐associated coagulopathy appears to be rare, as it was not identified in our large cohort of patients with MBD. Soluble TM did not arise as a risk factor for bleeding or altered haemostasis in these patients.

How I treat. Bleeding Disorder of Unknown Cause (BDUC)

Recent studies have demonstrated that only 30% of patients referred for assessment of a possible bleeding tendency will eventually be diagnosed with a mild bleeding disorder (MBD) such as von Willebrand disease (VWD) or platelet function defect (PFD). Rather, the majority of such patients will be diagnosed with Bleeding Disorder of Unknown Cause (BDUC). There remains an important unmet need to define consensus regarding the clinical and laboratory criteria necessary for a formal BDUC diagnosis. Nevertheless, BDUC already accounts for more than 10% of patients registered in some Haemophilia Comprehensive Care centres. Accumulating recent data suggest that BDUC is also being diagnosed with increasing frequency. Increased BAT scores are widely utilized to differentiate significant from trivial symptoms in patients with mucocutaneous bleeding. Objective assessment of bleeding phenotype using a standardised bleeding assessment tool (BAT) therefore represents a fundamental first step in the diagnosis of BDUC. Since BDUC is a diagnosis by exclusion, accurate quantification of bleeding phenotype is critical as this will be the primary determinant upon which a diagnosis of BDUC is reached. Importantly, BAT scores suggest that patients with BDUC display bleeding phenotypes comparable to those seen in patients with VWD or PFD respectively. Despite the prevalence of BDUC, diagnosis and management of these patients commonly pose significant clinical dilemmas. In this manuscript, we consider these challenges in the context of a number of typical case studies, discuss the available evidence and outline our approach to the management of these patients.

Preoperative bleeding risk assessment with ISTH-BAT and laboratory tests in patients undergoing elective surgery: A prospective cohort study

BACKGROUND

Patients with inherited haemorrhagic disorders may bleed during surgery. No questionnaire on bleeding diathesis has been yet validated for the preoperative period and current guidelines provide conflicting recommendations.

AIM

We aimed to assess if preoperative assessment with ISTH-BAT (International Society on Thrombosis and Haemostasis Bleeding Assesment Tool) and laboratory screening tests is useful to identify mild previously undiagnosed bleeding disorders (BDs) and to predict bleeding complications in selected patients undergoing elective surgery.

METHODS

Consecutive patients undergoing elective surgery received ISTH-BAT evaluation and laboratory screening for platelet count, Prothrombin Time (PT) and activated Partial Thromboplastin Time (aPTT). Subjects with an abnormal ISTH-BAT and/or laboratory results underwent further testing, and they were compared with a 1:1 random gender-, age- and type of surgery- matched control group.

RESULTS

Overall, 1502 consecutive surgical patients (1186 adults, 316 children) were enrolled. Of these, 83 (5.5%, 95% confidence interval 4.4-6.8) patients (37 adults and 46 children) had an abnormal ISTH-BAT, and/or prolonged PT and/or prolonged aPTT and/or low platelet count; of them, one subject had low von Willebrand factor level, three Factor XII deficiency and four anticardiolipin and/or antiB2GPI antibodies. No major bleeding was reported in these 83 patients and their controls.

CONCLUSION

ISTH-BAT and laboratory screening tests do not accurately detect mild BDs in selected patients undergoing elective surgery.

Natural anticoagulants: A missing link in mild to moderate bleeding tendencies

Introduction

There is a growing interest in natural anticoagulants as a cause of mild to moderate bleeding disorders (MBDs), particularly in patients with bleeding of unknown cause (BUC), which is defined as having a mild to moderate bleeding phenotype without a definite diagnosis despite exhaustive and repeated laboratory investigations. Recently, abnormalities in two natural anticoagulant pathways, thrombomodulin (TM), and tissue factor pathway inhibitor (TFPI), were identified in single patients or families as the underlying cause for a bleeding tendency.

Aim

The objective of this review is to discuss the current understanding of the role of natural anticoagulants in MBDs using available clinical and translational data.

Methods

A Cochrane Library and PubMed (MEDLINE) search focusing on selected natural anticoagulants and their role in MBDs was conducted.

Results

Data on the influence of natural anticoagulants including protein C, protein S, antithrombin, TM, and TFPI or factors with anticoagulant properties like fibrinogen gamma prime (γ’) on MBDs are scarce. Observations from sepsis treatment and from translational research highlight their importance as regulators of the haemostatic balance, especially via the activated protein C‐related pathway, and suggest a role in some MBDs.

Conclusion

Similar to the distinct genetic variants of natural anticoagulants linked to thrombosis, we hypothesize that novel variants may be associated with a bleeding tendency and could be identified using next generation sequencing.

Fibrinolysis and bleeding of unknown cause

Patients with bleeding of unknown cause (BUC) present with a variety of mild to moderate bleeding symptoms, but no hemostatic abnormalities can be found. Hyperfibrinolysis is rarely evaluated as the underlying cause for bleeding in clinical practice, and well-established global assays for abnormal fibrinolysis are lacking. Few patients with definitive fibrinolytic disorders, including α2-antiplasmin deficiency, plasminogen activator inhibitor 1 deficiency, or Quebec platelet disorder, have been reported. This review aims to summarize data on established fibrinolytic disorders and to discuss assessments of fibrinolysis in prior bleeding cohorts. Furthermore, we review available global tests with the potential to measure fibrinolysis, such as turbidity fibrin clot assays and rotational thromboelastometry, and their relevance in the workup of patients with BUC. We conclude that, due to the lack of adequate global tests, hyperfibrinolysis might be an underdiagnosed cause for a bleeding disorder. The diagnosis of hyperfibrinolytic bleeding disorders would improve patient care as effective treatment with antifibrinolytic agents is available.