Hemostasis Using Prothrombin Complex Concentrate in Patients Undergoing Cardiac Surgery: Systematic Review with Meta-Analysis.

OBJECTIVE: The purpose of present study was to comprehensívely explore the efficacy and safety of prothrombín complex concentrate (PCC) to treat massíve bleedíng in patíents undergoing cardiac surgery. METHODS: PubMed®, Embase, and Cochrane Líbrary databases were searched for studíes ínvestigating PCC administratíon duríng cardiac surgery published before September 10, 2022. Mean dífference (MD) wíth 95% confidence interval (CI) was applíed to analyze continuous data, and dichotomous data were analyzed as risk ratio (RR) with 95% CI. RESULTS: Twelve studies were included in the meta-analysis. Compared with other non-PCC treatment regimens, PCC was not assocíated with elevated mortality (RR=1.18, 95% CI=0.86-1.60, P=0.30, I2=0%), shorter hospital stay (MD=-2.17 days; 95% CI=-5.62-1.28, P=0.22, I2=91%), reduced total thoracic drainage (MD=-67.94 ml, 95% CI=-239.52-103.65, P=0.44, I2=91%), thromboembolíc events (RR=1.10, 95% CI=0.74-1.65, P=0.63, I2=39%), increase ín atríal fibríllatíon events (RR=0.73, 95% CI=0.52-1.05, P=0.24, I2=29%), and myocardial infarction (RR=1.10, 95% CI=0.80-1.51, P=0.57, I2=81%). However, PCC use was associated with reduced intensive care unit length of stay (MD=-0.81 days, 95% CI=-1.48- -0.13, P=0.02, I2=0%), bleeding (MD=-248.67 ml, 95% CI=-465.36- -31.97, P=0.02, I2=84%), and intra-aortic balloon pump/extracorporeal membrane oxygenation (RR=0.65, 95% CI=0.42-0.996, P=0.05, I2=0%) when compared with non-PCC treatment regimens. CONCLUSION: The use of PCC in cardiac surgery did not correlate with mortality, length of hospítal stay, thoracic drainage, atríal fibríllatíon, myocardíal ínfarction, and thromboembolíc events. However, PCC sígnificantly improved postoperatíve intensíve care unít length of stay, bleedíng, and intra-aortic balloon pump/ extracorporeal membrane oxygenation outcomes ín patients undergoing cardíac surgery.

Isolated Prothrombin Deficiency: A Case Report of a Rare Coagulation Disorder and Review of Literature.

Congenital prothrombin deficiency is a rare hemorrhagic disorder, frequent in areas with high degrees of consanguinity as it is autosomal recessive in nature. Clinical manifestations are highly variable, ranging from mild episodes of bleeding to severe hemorrhages. Here, we report a child with isolated prothrombin deficiency who presented with a history of pain and soreness in the prepuce associated with bleeding. Laboratory evaluation showed an altered coagulation profile with a prothrombin activity level of 29.8%, indicative of factor-II deficiency. This case highlights the importance of coagulation screening in all patients before even minor invasive procedures and the role of a detailed coagulation profile in confirming a diagnosis in the case of abnormal screening tests.

International Normalized Ratio Predicts Recurrence and Bleeding in Patients With Acute Venous Thromboembolism Who Undergo Direct Oral Anticoagulants.

Prothrombin time/international normalized ratio (PT/INR) is related to both antithrombotic effect and risk of bleeding. Its role in the prediction of venous thromboembolism (VTE) recurrence and bleeding for patients with acute VTE who undergo direct oral anticoagulants (DOACs) treatment is unclear, despite previous studies revealed some association between them. The predictive efficiency of INR for VTE recurrence and bleeding were analyzed in a retrospective cohort with VTE patients who underwent DOACs treatment. Then its predictive efficiency for VTE recurrence and bleeding were validated in a prospective cohort with the acquired cutoffs range, and compared with anti-Xa level, DASH and VTE-BLEED scores. In the retrospective cohort (n = 1083), the sensitivity and specificity of INR for the prediction of VTE recurrence were 79.4% and 92.8%, respectively. The area under the curve (AUC) was 0.881 (0.803-0.960)(P = .025). The cutoff value of INR was 0.9. The sensitivity and specificity of INR for the prediction of bleeding were 85.7% and 77.9%, respectively. The AUC was 0.876 (0.786-0.967)(P < .001). The cutoff value of INR was 2.1. In the prospective cohort (n = 202), the calibration showed that there were 4 (50%) patients with VTE recurrence, 156 (97.5%) patients with non-recurrence and bleeding (non-R&B), and 20 (58.8%) patients with bleeding in the low (INR < 0.9)(n = 8), intermediate (0.9 ≤ INR ≤ 2.1)(n = 160), and high (INR > 2.1)(n = 34) groups, respectively. The baseline PT/INR value at the initiation of DOACs treatment is an independent predictor for VTE recurrence and bleeding in patients with acute VTE who undergo DOACs treatment.

Evaluation of modified fixed dose four-factor prothrombin complex concentrate for warfarin reversal.

Non-activated four-factor prothrombin complex concentrate (4 F-PCC) has emerged as the preferred reversal strategy for patients on warfarin with life-threatening bleeding. Current dosing recommendations for 4 F-PCC require pre-treatment international normalized ratio (INR) and bodyweight values, resulting in ordering and administration delays. Studies have shown that alternative dosing regimens are safe and efficacious. This retrospective, single-center, pre- and post-protocol analysis was conducted to assess the efficacy of a pharmacist driven modified fixed-dose 4 F-PCC regimen versus package insert weight- and INR-based dosing regimen for warfarin reversal. The primary outcome was achievement of INR less than two. Secondary outcomes included dose and cost of 4 F-PCC, a time analysis, incidence of concomitant vitamin K administration, and incidence of thrombosis within seven days of 4 F-PCC. There were 195 patients included in the analysis, with 74 in the pre-cohort and 121 in the post-cohort. Baseline characteristics were similar between cohorts with the most common indication for warfarin use being atrial fibrillation (48.6% versus 47.1%) and reversal being intracerebral hemorrhage (68.9% versus 43.0%). Achievement of the primary endpoint occurred in 92% versus 95% (p = 0.097) of patients. A statistically significant difference was seen between cohorts regarding median dose and cost of 4 F-PCC administered (p < 0.001). Eleven thromboembolic events occurred with three events in the pre-cohort and eight events in the post-cohort (p = 0.453). A fixed-dose of 1500IU of 4 F-PCC was effective in reversing INR to less than two in most patients regardless of reversal indication with minimal thrombotic risks.

Unified Methodology for the Primary Preclinical In Vivo Screening of New Anticoagulant Pharmaceutical Agents from Hematophagous Organisms.

The development of novel anticoagulants requires a comprehensive investigational approach that is capable of characterizing different aspects of antithrombotic activity. The necessary experiments include both in vitro assays and studies on animal models. The required in vivo approaches include the assessment of pharmacokinetic and pharmacodynamic profiles and studies of hemorrhagic and antithrombotic effects. Comparison of anticoagulants with different mechanisms of action and administration types requires unification of the experiment scheme and its adaptation to existing laboratory conditions. The rodent thrombosis models in combination with the assessment of hemostasis parameters and hematological analysis are the classic methods for conducting preclinical studies. We report an approach for the comparative study of the activity of different anticoagulants in vivo, including the investigation of pharmacodynamics and the assessment of hemorrhagic effects (tail-cut bleeding model) and pathological thrombus formation (inferior vena cava stenosis model of venous thrombosis). The reproducibility and uniformity of our set of experiments were illustrated on unfractionated heparin and dabigatran etexilate (the most common pharmaceuticals in antithrombic therapy) as comparator drugs and an experimental drug variegin from the tick Amblyomma variegatum. Variegin is notorious since it is a potential analogue of bivalirudin (Angiomax, Novartis AG, Basel, Switzerland), which is now being actively introduced into antithrombotic therapy.

The association of the prothrombin A19911G single-nucleotide polymorphism and the risk of venous thromboembolism: A systematic review and meta-analysis.

BACKGROUND: The study employed meta-analysis to provide a comprehensive synthesis of evidence regarding the association between the prothrombin A19911G polymorphism and the risk of venous thromboembolism (VTE). METHOD: The databases were searched to identify studies investigating the association between the prothrombin A19911G polymorphism and the risk of VTE. Meta-analysis was conducted using Stata 14.0 software. RESULTS: A total of five literature studies were included, involving 14,001 participants. Meta-analysis demonstrated that prothrombin A19911G polymorphism increased the risk of VTE (G vs A: OR = 1.17, 95% CI = 1.11-1.22, p < .00001; GG + AG vs AA: OR = 1.22, 95% CI = 1.13-1.31, p < .00001; GG vs AG + AA: OR = 1.23, 95% CI = 1.14-1.33, p < .00001; AG vs AA: OR = 1.15, 95% CI = 1.06-1.25, p = .0006; GG vs AA: OR = 1.34, 95% CI = 1.22-1.48, p < .00001). CONCLUSION: The polymorphism of prothrombin A19911G enhances the susceptibility to VTE.

Short-term treatment with cholestyramine increases long-acting anticoagulant rodenticide clearance from rabbits without affecting plasma vitamin K1 levels nor blood coagulation.

Administration of high dose vitamin K1 (VK1) overcomes coagulopathy and bleeding elicited by acute poisoning with long-acting anti-coagulant rodenticides (LAARs). However, long-term (months) treatment is required due to long LAAR biological half-lives that may lead to poor compliance and recurrent coagulopathy. The half-lives of LAARs are extended by slow metabolism, and similar to warfarin, are thought to undergo enterohepatic recirculation. We now show that treatment with the bile acid sequestrant cholestyramine (CSA) administered concomitantly with VK1 decreases plasma LAAR levels and increases LAAR fecal excretion. Daily CSA treatment for 14 days did not reduce plasma VK1 levels, nor increase prothrombin time. Collectively, these data show that CSA accelerates LAAR clearance from rabbits without adverse effects on VK1 anti-coagulation, and could provide an additional therapeutic option for treatment of LAAR poisoning.

Deep Vein Thrombosis as the Presenting Sign in an Adolescent With New-Onset Type 2 Diabetes.

Prothrombin G20210A mutation occurs in only 2% to 3% of the population, but usually does not become apparent unless the individual exhibits another risk factor for clotting. A risk factor such as hyperglycemia in the setting of diabetes mellitus may accelerate this clotting process, even at a very young age. In this case report, we discuss a 15-year-old boy presenting with left calf swelling and pain, found to have extensive deep vein thrombosis in the setting of hyperglycemia and a newly discovered prothrombin G20210A mutation. Venous thromboembolism in the setting of type 2 diabetes mellitus has not been described in children.

Effect of Reduced INR in Early Pregnancy on the Occurrence of Preeclampsia: A Retrospective Cohort Study.

To investigate the effect of reduced early-pregnancy activated partial thrombin time (APTT), prothrombin time (PT), and international standardized ratio (INR) on the risk of preeclampsia. A total of 8549 pregnant women with singleton births were included. Early pregnancy APTT, PT, and INR levels, with age, birth, prepregnancy body mass index, fibrinogen (FBG), thrombin time (TT), D-dimer (DD2), antithrombin III (ATIII), fibrin degradation products (FDP) as confounders, generalized linear model of APTT, the relative risk of PT and INR when INR reduction. After adequate adjustment for confounders, the relative risk of preeclampsia was 0.703 for every 1 s increase in plasma PT results in early pregnancy, and for every 0.1 increase in plasma INR results, the relative risk of preeclampsia was 0.767. With a PT less than the P25 quantile (<11 s), the relative risk of preeclampsia was 1.328. The relative risk of preeclampsia at an INR less than the P25 quantile (<0.92) was 1.24. There was no statistical association between APTT on the risk of preeclampsia. The relative risk of preeclampsia is strongly associated with a decrease in PT and INR in early pregnancy. PT and INR in early pregnancy were a potential marker in the risk stratification of preeclampsia. Focusing on reduced PT and INR levels in early pregnancy can help to identify early pregnancies at risk for preeclampsia.

Zinc supplementation with polaprezinc was associated with improvements in albumin, prothrombin time activity, and hemoglobin in chronic liver disease.

Zinc deficiency occurs in a variety of diseases, including chronic liver disease (CLD). We investigated the correlation between zinc levels and biochemical and hematological tests in CLD and the effect of zinc supplementation with polaprezinc on these values. The first study (Study 1) was a retrospective observational study of 490 patients with CLD not receiving zinc supplementation, with data available from September 2009 to August 2021. Univariate and multiple regression analysis showed that serum zinc levels correlated most strongly with albumin (Alb) and also significantly with prothrombin time activity (PT%) and hemoglobin (Hb). A subsequent study (Study 2) focused on patients with advanced CLD who used polaprezinc for more than 90 days between January 2005 and August 2021. Using a self-controlled design with the 6-month period prior to polaprezinc as the control period, comparisons showed that Alb (p<0.0001), PT% (p<0.0005), and Hb (p<0.01) were significantly improved in the polaprezinc-treated patients compared to the control group. In conclusion, serum zinc levels were correlated with serum Alb, Hb, and PT% in patients with CLD, and zinc supplementation with polaprezinc was associated with improvements in Alb, Hb, and PT% within at least 6 months.

The frequency and timing of sepsis-associated coagulopathy in the neonatal intensive care unit.

Introduction: Sepsis is a common cause of morbidity and mortality in the neonatal intensive care unit (NICU). The frequency and severity of sepsis-associated coagulopathy as well as its relationship to illness severity are unclear. Methods: We performed a single-center, retrospective, observational cohort study of all infants admitted to the University of Florida Health (UF Health), level IV NICU between January 1st 2012 to March 1st 2020 to measure the frequency of sepsis-associated coagulopathy as well as its temporal relationship to critical illness in the NICU population. All clinical data in the electronic health record were extracted and deposited into an integrated data repository that was used for this work. Results: We identified 225 new sepsis episodes in 216 patients. An evaluation for sepsis-associated coagulopathy was performed in 96 (43%) episodes. Gram-negative pathogen, nSOFA score at evaluation, and mortality were greater among episodes that included a coagulopathy evaluation compared with those that did not. Abnormal coagulation results were common (271/339 evaluations; 80%) and were predominantly prothrombin times. Intervention (plasma or cryoprecipitate) followed a minority (84/271; 31%) of abnormal results, occurred in 40/96 (42%) episodes that were often associated with >1 intervention (29/40; 73%), and coincided with thrombocytopenia in 37/40 (93%) and platelet transfusion in 27/40 (68%). Shapley Additive Explanations modeling demonstrated strong predictive performance for the composite outcome of death and/or treatment for coagulopathy in neonates (f1 score 0.8, area under receiver operating characteristic curve 0.83 for those with abnormal coagulation values). The three most important features influencing the composite outcome of death or treatment for coagulopathy included administration of vasoactive medications, hematologic dysfunction assessed by the maximum nSOFA platelet score, and early sepsis (≤72 h after birth). Conclusions: A coagulopathy evaluation was performed in a minority of NICU patients with sepsis and was associated with greater illness severity and mortality. Abnormal results were common but infrequently associated with intervention, and intervention was contemporaneous with thrombocytopenia. The most important feature that influenced the composite outcome of death or treatment for coagulopathy was the administration of vasoactive-inotropic medications. These data help to identify NICU patients at risk of sepsis-associated coagulopathy.

A simple method to resolve rate constants when the binding mechanism obeys induced fit or conformational selection.

Many interactions involving a ligand and its molecular target are studied by rapid kinetics using a stopped-flow apparatus. Information obtained from these studies is often limited to a single, saturable relaxation that is insufficient to resolve all independent rate constants even for a two-step mechanism of binding obeying induced fit (IF) or conformational selection (CS). We introduce a simple method of general applicability where this limitation is overcome. The method accurately reproduces the rate constants for ligand binding to the serine protease thrombin determined independently from the analysis of multiple relaxations. Application to the inactive zymogen precursor of thrombin, prethrombin-2, resolves all rate constants for a binding mechanism of IF or CS from a single, saturable relaxation. Comparison with thrombin shows that the prethrombin-2 to thrombin conversion enhances ligand binding to the active site not by improving accessibility through the value of kon but by reducing the rate of dissociation koff. The conclusion holds regardless of whether binding is interpreted in terms of IF or CS and has general relevance for the mechanism of zymogen activation of serine proteases. The method also provides a simple test of the validity of IF and CS and indicates when more complex mechanisms of binding should be considered.

Evaluation of D-dimer and prothrombin time in alcohol related liver cirrhosis with comparison of machine learning analyses.

OBJECTIVES: Liver cirrhosis (LC) can be caused by obesity, alcohol consumption, viral infection, and autoimmune disease. Early diagnosis and management of LC is important for patient quality of life. Non-invasive diagnostic methods are useful for predicting the current status and mortality risk of LC. The purpose of this study is to identify relevant diagnostic factors measured in routine laboratory test of alcohol-related liver cirrhosis (ALC) patients. METHODS: This study analyzed data from 127 patients with ALC, including their laboratory test results and clinical information, including coagulation parameters, hematologic parameters, and biochemical parameters. These data were used to compare the performance of the prediction models from three machine learning algorithms including K-nearest neighbor (KNN), support vector machine (SVM), and random forest (RF). RESULTS: Higher Model for End-stage Liver Disease (MELD) score were associated with prothrombin time (PT) and D-dimer. Logistic and multiple linear regression analyses revealed significant factors predicting mortality in the MELD group. Machine learning approaches were used to predict death in ALC patients using some laboratory parameters associated with mortality. The prediction model based on SVM exhibited better prediction performance than others. CONCLUSION: PT and D-dimer were the factors that were most strongly associated with 90-day mortality, and machine learning methods can create prediction models with good predictive power.

Effect of low- versus high-dose 4-factor prothrombin complex concentrate in factor Xa inhibitor-associated bleeding: A qualitative systematic review.

DISCLAIMER: In an effort to expedite the publication of articles, AJHP is posting manuscripts online as soon as possible after acceptance. Accepted manuscripts have been peer-reviewed and copyedited, but are posted online before technical formatting and author proofing. These manuscripts are not the final version of record and will be replaced with the final article (formatted per AJHP style and proofed by the authors) at a later time. PURPOSE: The purpose of this review is to evaluate current literature on the treatment of factor Xa inhibitor-associated bleeds with 4-factor prothrombin complex concentrate (4F-PCC), with a focus on the effect of low versus high dosing of 4F-PCC on hemostatic efficacy and safety outcomes. SUMMARY: A search of PubMed and EBSCOhost was performed to identify studies evaluating patients with a factor Xa inhibitor-bleed treated with 4F-PCC at either low or high doses. Studies of patients receiving alternative reversal agents such as fresh frozen plasma and andexanet alfa or where no comparator group was evaluated were excluded from the analysis. To assess the effect of these 4F-PCC dosing strategies, the primary outcome of interest was hemostatic efficacy. Four studies meeting inclusion criteria were included in this review. In each of the included studies, similar rates of hemostatic efficacy, hospital mortality, and venous thromboembolism were observed in the low- and high-dose cohorts. CONCLUSION: These results suggest low- and high-dose 4F-PPC may confer similar clinical effectiveness and safety; however, these findings should be evaluated and confirmed with future prospective studies.

The Contribution of Inherited Thrombophilia to Venous Thromboembolism in Cancer Patients.

Although the relationship between venous thromboembolism (VTE) and cancer has been a subject of study, knowledge of the contribution of thrombophilia to thrombosis in patients with cancer is still very limited. The aim of this article is to collect present knowledge on the contribution of inherited thrombophilia to VTE in cancer patients. We performed a search in Google Scholar and PubMed and selected 21 from 76 returned articles. Then we made a narrative review of the selected articles. We describe 11 studies on the contribution of inherited thrombophilia to VTE in cancer patients in general and 10 on that contribution in specific types of cancer: 1 in colorectal cancer, 4 in breast cancer, 1 in gynecologic cancer and 4 in hematopoietic malignancies. All studies investigate the relation of factor V Leiden (FVL) to VTE, 13 that of the prothrombin G20210A mutation (PTG20210A) and 7 studies also investigate other inherited thrombophilias, such methylenetetrahydrofolate reductase gene mutations, although only 2 investigate the contribution of deficiencies of the natural anticoagulants. Studies are very heterogeneous, in design and sample size and conclusions differ considerably. There is no consensus on the contribution of inherited thrombophilia to VTE in cancer patients except for acute lymphoblastic leukemia in children. Probably, that contribution is not the same for all types of cancer and more studies are needed to bring more knowledge on this subject.

Post-lumbar puncture cerebral vein thrombosis.

Lumbar puncture (LP) is rarely complicated by cerebral vein thrombosis (CVT), especially if other risk factors coexist. We describe the case of a 28-year-old woman who developed CVT after corticosteroid treatment and LP performed for suspected multiple sclerosis. The day after LP, she developed intense headache and on Day 8 generalized tonic-clonic seizures. A brain computed tomography scan showed thrombosis of the superior sagittal sinus and cortical veins. Thrombophilia screening showed heterozygous G20210A prothrombin mutation. Anticoagulant therapy with low molecular weight heparin and then warfarin was administered until Day 16 after LP, when a brain magnetic resonance imaging showed a subdural hematoma. Warfarin was interrupted and dabigatran was started. The patient recovered completely, both from the initial thrombotic event and the hemorrhagic complication. This case highlights the importance to keep in mind CVT in the differential diagnosis of post-LP headache not responsive to standard therapy, and suggests that dabigatran can be considered an effective and safe treatment of CVT.

Real-World Safety and Effectiveness of a 4-Factor Prothrombin Complex Concentrate in Japanese Patients Experiencing Major Bleeding: A Post-marketing Surveillance Study.

INTRODUCTION: Limited data are available regarding the safety and effectiveness of 4-factor prothrombin complex concentrate (4F-PCC) in patients experiencing major hemorrhage or requiring expeditious surgical intervention, both globally and within Japan. METHODS: We executed a prospective, observational post-marketing surveillance study of patients receiving 4F-PCC for the first time between September 19, 2017 and August 15, 2018 in Japan. Patients were subjected to a comprehensive follow-up for a duration of 4 weeks. RESULTS: Of 1381 eligible patients, 1271 (92%) received a vitamin K antagonist. Among these, 58% were aged ≥ 75 years, 49% manifested atrial fibrillation, 17% presented with valvular heart disease, and 6% exhibited venous thromboembolism. The median (range) international normalized ratio was 2.67 (0.96-27.11) at baseline and 1.21 (0.45-6.61) at first measurement post-administration of 4F-PCC. The most common reason for 4F-PCC administration was intracranial hemorrhage (59.6%), followed by gastrointestinal bleeding (6.6%). Hemostatic effectiveness was achieved in 85.8% of patients. The incidences of adverse drug reactions (ADRs) and serious ADRs were 3.9% and 2.8%, respectively. Thromboembolic events (TEEs) occurred in 20 (1.5%) patients, with a mean onset of 10 days. The majority of TEEs were classified as nervous system disorders (55%). At the time of TEE, only 13% of patients resumed anticoagulant therapy. CONCLUSION: The incidence of TEEs following treatment with 4F-PCC did not surpass those observed in phase 3 trials. No novel safety signals were identified. The safety and effectiveness of 4F-PCC in Japanese real-world practice were in harmony with the observations of prior studies.

Prothrombin conversion and thrombin decay in patients with cirrhosis-role of prothrombin and antithrombin deficiencies.

BACKGROUND: Thrombin generation (TG) in the presence of thrombomodulin (TG-TM) in the plasma of patients with cirrhosis (PWC) is tilted toward a hypercoagulable phenotype. Low protein C and elevated factor VIII levels play a role, but other determinants, such as the prothrombin/antithrombin pair, must also be studied. OBJECTIVES: The objectives were (i) to quantitatively assess the subprocesses (prothrombin conversion and thrombin decay) and (ii) to understand the underlying mechanism by studying TG dynamics after prothrombin and antithrombin plasma level correction in PWC. METHODS: We studied TG-TM in plasma samples of 36 healthy controls (HCs) and 41 PWC with prothrombin and antithrombin levels of <70% and after their correction. We initiated coagulation with an intermediate picomolar concentration of tissue factor. We determined the overall thrombin potential, prothrombin conversion, and thrombin decay. RESULTS: TG-TM was increased in PWC compared with HC due to impaired thrombin inhibition. Indeed, thrombin decay capacity (min-1) decreased from 0.37 (0.35-0.40) in HC to 0.33 (0.30-0.37) in the Child-Turcotte-Pugh A (CTP-A; P = .09), 0.27 (0.26-0.30) in the CTP-B (P < .001), and 0.20 (0.19-0.20) in the CTP-C (P < .001) group. Concomitant correction of prothrombin and antithrombin increased endogenous thrombin potential with prothrombin conversion surpassing thrombin decay. By contrast, when we corrected only antithrombin, TG-TM was normalized and even consistent with a hypocoagulable phenotype in the CTP-C group. CONCLUSION: Our results highlight that in PWC, hypercoagulability (evidenced in the presence of TM) is due to impaired thrombin decay, whereas low prothrombin levels do not translate into decreased prothrombin conversion, likely due to altered TM-activated protein C negative feedback.

Viewpoint: The value of non-criteria antiphospholipid antibodies.

In 2006, at a meeting in Sydney, Australia, consensus was reached by an international group of specialists to establish a number of serological criteria that identify patients with a history of thrombosis or pregnancy complications as having antiphospholipid syndrome (APS). These criteria were originally formulated for research purposes and to compare clinical trials in different centres. However, these same criteria are now generally used and accepted for the diagnosis and treatment of patients. The practice of using these criteria for direct patient care requires that these criteria are based on sound scientific evidence. Indeed, for all the autoantibodies that are officially included in the serological criteria, it has been shown that they induce thrombosis and fetal loss when infused into mice. There are also a number of additional autoantibodies that have been identified in these patients but for these antibodies there was not enough evidence to meet the official APS criteria in 2006. Seventeen years have now passed since the consensus meeting, therefore, this review examines whether additional studies performed with these 'non-criteria' autoantibodies have provided sufficient results to suggest the inclusion of these autoantibodies in the official serological criteria of APS.