Routine Coagulation Screening Tests Research Articles

Utilization of International Normalized Ratio-Derived Formula to Predict Plasma Rivaroxaban Level - Validation Study and Real-World Experience

Introduction: Specific assay of plasma rivaroxaban level are not always readily available with short turn-around-time which hampered the management of urgent clinical situations. The response of routine coagulation screening tests show huge lot-to-lot differences with the plasma rivaroxaban level. International normalized ratio (INR) is a standardized measurement taking into account of lot-to-lot variations of PT reagents. In this study, we aimed to build a predictive formula of plasma rivaroxaban levels from INR value and validated in real world clinical situations. Method: The study period was 1 st January 2018 to 31 st December 2021. Ninety-four patients who taking rivaroxaban participated in the study. Patients were randomized into testing cohort and validation cohorts. The prediction formula was built from the testing cohort and then validated in validation cohort. The predictive performance was further validated on real-world clinical requests. Results: The baseline characteristics of both cohorts were well-balance. There was significant correlation between the plasma rivaroxaban level and PT in both the testing and validation cohorts (Testing cohort: R square 0.838, p < 0.01; Validation cohort: R square 0.836, p < 0.01). The plasma rivaroxaban level showed significant correlation with APTT in both the testing and validation cohorts (Testing cohort: R square 0.744, p < 0.01; Validation cohort: R square 0.654, p < 0.01). There was also significant correlation between INR and plasma rivaroxaban levels in both the testing and validation cohorts (Testing cohort: R square 0.819, p <0.01; Validation cohort: R square 0.816, p < 0.01). Both INR and plasma rivaroxaban levels were undergone natural logarithmic transformation. We choose the quadratic model to determine the relationship between the natural log of plasma rivaroxaban level and the natural log of INR as it had highest R square value (R square 0.850, p<0.01). The formula is: ln (plasma rivaroxaban level) = 2.96+7.87 X ln (INR) - 5.04X (ln (INR))^2. The root mean square error (RMSE) of the predictive formula for the testing and validation cohorts were 61.81 ng/ml and 69.32 ng/ml, respectively. We received a total of 43 requests for plasma rivaroxaban assay involved 29 patients during the study period (Table 1). Three patients had multiple requests for plasma DOAC level assays during this period. The cut-off INR value was 1.3 for administration of antidote for rivaroxaban, which corresponded to a rivaroxaban level of 75 ng/ml. The sensitivity and specificity for using this INR cut-off value to determine the threshold plasma rivaroxaban level (75 ng/ml) for administration of reversal agents were 95% (95%CI: 85.4 -100%) and 87.5% (95%CI:71.3-100%) respectively in real world clinical situations (Table 2). Conclusion: Plasma rivaroxaban level can be calculated from prediction formula by INR value with satisfactory accuracy and the INR cut-off value derived from it can be used to guide the decision for administration of reversal agents with excellent sensitivity and specificity.

Utility of International Society on Thrombosis and Hemostasis Bleeding Assessment Tool (ISTH-BAT) in Patients with Inherited Bleeding Disorders: A Cross-Sectional Study from Southern India.

The International Society on Thrombosis and Hemostasis bleeding assessment tool (ISTH-BAT) was developed to record bleeding symptoms and aid in patient diagnosis. This study was done to investigate the utility of ISTH-BAT in patients suspected to have inherited bleeding disorders. This cross-sectional study was conducted in a tertiary care hospital in Southern India over 3 and 1/2years. A trained investigator administered the ISTH-BAT questionnaire to 432 patients undergoing evaluation for inherited bleeding disorder prior to routine coagulation screening and confirmatory tests and to 131 healthy volunteers as controls. Among patients, 42(9.7%) had primary hemostatic defect, 150(34.7%) had secondary hemostatic defects and 229(53%) had normal screening coagulogram with mean bleeding scores (BS) being 5.9, 6.9, and 4.2 respectively and the proportion of patients with abnormal BS being 69%, 88.7% and 59.4% respectively; the latter qualifying as unknown hemostatic defect. 11(2.5%) with acquired hemostatic defect on workup were excluded. The mean BS was 1.52 among healthy volunteers. Common bleeding patterns were epistaxis (73.8%), cutaneous bleeding (52.4%), hematuria (54.8%), menorrhagia (50%) in primary hemostatic defect; cutaneous bleeding (72%), muscle hematoma (58.7%), hemarthrosis (46.7%), menorrhagia (58.7%) in secondary hemostatic defects and epistaxis (45.9%), cutaneous bleeding (62.4%), menorrhagia (30.7%) in normal screening coagulogram group. Grade of bleeding was mostly 2 and sometimes 4 in primary, 2-4 in secondary and 1-2 in normal screening coagulogram group. ISTH-BAT is a valuable tool to record lifelong bleeding history. The pattern and score give clues regarding the nature and severity of the bleeding disorder.

Bleeding after tonsillectomy

Oropharyngeal hemorrhage after tonsillectomy is one of the most common postprocedural ENT emergencies that require immediate attention. Management choices depend on the severity of bleeding, underlying platelet or coagulation disorders, and the patient’s maturity and age. Treatment range from simple observation to an emergent need to both secure the airway and stop the hemorrhage. The workup of the hemorrhagic patient will be discussed from the preoperative to postoperative time period. Surgical techniques in response to various acuity will be discussed to fully elucidate options to control the hemorrhage.

A comparison study of routine coagulation screening tests (PT and APTT) by three automated coagulation analyzers

Background: In recent times, growing coagulation test volume and constricted personnel budgets have enhanced interest in automated coagulation analyzers. Objective: (i) To compare the reliability of routine coagulation test [prothrombin time (PT) and activated partial thromboplastin time (APTT)] using mechanical, photo-optical, and nephelemetric methods by three automated coagulation analyzers. (ii) To evaluate the performance of a newly installed fully automatic coagulation analyzer [STA Compact Max (Stago)] and compare the consistency of its testing results with the confirmed clinical automatic coagulation analyzer at our department (Sysmex and ACL Top). Materials and Methods: Trisodium citrated (3.2%) 60 blood samples, which came to special (coagulation) laboratory with request of PT and APTT (with or without anticoagulant, abnormal, and normal/controls), Transfusion Medicine and Immunohematology Department, Christian Medical College, Vellore, Tamil Nadu, India, were included into study randomly. Sample were run on Sysmex CS2000i (Sysmex Corporation, Japan), photo-optical clot detection; ACL Top (Instrumentation Laboratory, USA), nephelometry clot detection method; and STA Compact Max (Stago, USA), viscosity-based (mechanical) clot detection. Result: Correlation was determined using Bland and Altman analysis, which demonstrated a good agreement between Sysmex CS2000i, ACL Top, and STA Compact Max for PT and APTT. A total of 10 samples (16.7%) with visually observed interferences were identified and tested on all three analyzers and showed good agreement with optical and mechanical methods. Conclusion: This study showed good agreement between newly installed STA Compact Max based on mechanical endpoint detection method with already standardized Sysmex CS 2000i and ACL Top, which work on photo-optical endpoint detection method, for evaluation of screening coagulation tests such as PT and APTT even in case of variables such as partially lysed/icteric samples. Three automated analyzers can be used interchangeably.

Role of coagulation profile in the management of patient with epistaxis

Epistaxis is a common emergency in otorhinolaryngology. Most patients with epistaxis don’t have an identifiable cause. The role of routine coagulation screening in the management of patients with epistaxis is unclear. The aim of this study was to observe the significance of routine coagulation screening tests in patients suffering from epistaxis. There are various treatment modalities for epistaxis. The study concludes that there is no role for routine coagulation profile in all the patients with epistaxis, which should only be performed when clinically indicated and most of the patients with epistaxis are managed with simple measures. DOI: http://dx.doi.org/10.3126/jcmc.v4i3.11937Journal of Chitwan Medical College 2014; 4(3):32-33

Novel heterozygous dysfibrinogenemia, Sumida (AαC472S), showed markedly impaired lateral aggregation of protofibrils and mildly lower functional fibrinogen levels

IntroductionWe encountered a 6-year-old girl with systemic lupus erythematosus. Although no bleeding or thrombotic tendency was detected, routine coagulation screening tests revealed slightly lower plasma fibrinogen levels, as determined by functional and antigenic measurements (functional/antigenic ratio=0.857), suggesting hypodysfibrinogenemia. Materials and methodsDNA sequence and functional analyses were performed on purified plasma fibrinogen, and recombinant variant fibrinogen was synthesized in Chinese hamster ovary cells based on the results obtained. ResultsDNA sequencing revealed a heterozygous AαC472S substitution (mature protein residue number) in the αC-domain. AαC472S fibrinogen indicated the presence of additional disulfide-bonded molecules, and markedly impaired lateral aggregation of protofibrils in spite of slightly lower functional plasma fibrinogen levels. Scanning electron microscopic observations showed a thin fiber fibrin clot, and t-PA and plasminogen-mediated clot lysis was similar to that of a normal control. Recombinant variant fibrinogen-producing cells demonstrated that destruction of the Aα442C-472C disulfide bond did not prevent the synthesis or secretion of fibrinogen, whereas the variant Aα chain of the secreted protein was degraded faster than that of the normal control. ConclusionOur results suggest that AαC472S fibrinogen may cause dysfibrinogenemia, but not hypofibrinogenemia. The destruction and steric hindrance of the αC-domain of variant fibrinogen led to the impaired lateral aggregation of protofibrils and t-PA and plasminogen-mediated fibrinolysis, as well as several previously reported variants located in the αC-domain, and demonstrated the presence of disulfide-bonded molecules.

Recombinant γT305A fibrinogen indicates severely impaired fibrin polymerization due to the aberrant function of hole ‘a’ and calcium binding sites

IntroductionWe examined a 6-month-old girl with inherited fibrinogen abnormality and no history of bleeding or thrombosis. Routine coagulation screening tests showed a markedly low level of plasma fibrinogen determined by functional measurement and also a low level by antigenic measurement (functional/antigenic ratio=0.295), suggesting hypodysfibrinogenemia. Materials and methodsDNA sequence analysis was performed, and γT305A fibrinogen was synthesized in Chinese hamster ovary cells based on the results. We then functionally analyzed and compared with that of nearby recombinant γN308K fibrinogen. ResultsDNA sequence analysis revealed a heterozygous γT305A substitution (mature protein residue number). The γT305A fibrinogen indicated markedly impaired thrombin-catalyzed fibrin polymerization both in the presence or absence of 1mM calcium ion compared with that of γN308K fibrinogen. Protection of plasmin degradation in the presence of calcium ion or Gly-Pro-Arg-Pro peptide (analogue for so-called knob ‘A’) and factor XIIIa-catalyzed fibrinogen crosslinking demonstrated that the calcium binding sites, hole ‘a’ and D:D interaction sites were all markedly impaired, whereas γN308Kwas impaired at the latter two sites. Molecular modeling demonstrated that γT305 is localized at a shorter distance than γN308 from the high affinity calcium binding site and hole ‘a’. ConclusionOur findings suggest that γT305 might be important for construction of the overall structure of the γ module of fibrinogen. Substitution of γT305A leads to both dysfibrinogenemic and hypofibrinogenemic characterization, namely hypodysfibrinogenemia. We have already reported that recombinant γT305A fibrinogen was synthesized normally and secreted slightly, but was significantly reduced.

Dabigatran Effects on the International Normalized Ratio, Activated Partial Thromboplastin Time, Thrombin Time, and Fibrinogen: A Multicenter, In Vitro Study

Patients receiving the direct thrombin inhibitor dabigatran may have selected anticoagulation assays performed as part of routine care. The effect of dabigatran on the international normalized ratio (INR), activated partial thromboplastin time (aPTT), thrombin time (TT), and fibrinogen requires clarification. To describe the effect of dabigatran on selected assays in North America and the United Kingdom. Pooled normal plasma enriched with dabigatran at concentrations of 25, 50, 75, 100, 125, 150, 200, 300, 400, and 500 ng/mL were sent blinded to 19 centers in the US, the UK, and Canada to assess the effect of dabigatran on routine coagulation screening tests, the INR, aPTT, TT, and fibrinogen. Data were returned from 16 centers. For effects on INR, Neoplastine CI Plus and Simplastin HTF were the most sensitive and Thromborel S the least sensitive to increasing dabigatran concentrations. For the aPTT, all reagents demonstrated decreasing sensitivity to increasing dabigatran concentrations. Measured fibrinogen either demonstrated no change or factitious decrease with increasing dabigatran concentrations. Commercial TT methods were very sensitive to low concentrations of dabigatran, with 9 of 10 reporting sites exceeding test limits at dabigatran concentrations of 100 ng/mL. The INR, aPTT, and TT rise as dabigatran concentrations increase. Both the INR and aPTT increase in a linear pattern with marginal slopes, creating challenges in using these assays as reliable means for assessing the amount of dabigatran present. The commercial TT assay is very sensitive at low concentrations of dabigatran. Fibrinogen test results may be either unaffected or lower in the presence of dabigatran.

Acute traumatic coagulopathy

Recent therapeutic and observational studies have demonstrated improved survival with better management of haemostasis early after injury. This review delineates our current understanding of the clinical importance, aetiology and pathophysiology of acute traumatic coagulopathy (ATC). Trauma causes an acute disruption of the equilibrium between all components of haemostasis (coagulation, anticoagulation, fibrinolysis, platelets and endothelium). In patients with a combination of severe tissue damage and systemic hypoperfusion, this will progress rapidly to an endogenous coagulopathy that is independently associated with worse outcomes. New discoveries of the interactions between neurohormonal, vascular, and coagulation systems are beginning to explain how this haemostatic impairment develops and offer novel targets for therapeutic manipulation. Routine coagulation screening tests are ineffective for diagnosing ATC and guiding resuscitation in real-time. Viscoelastic coagulation tests (such as ROTEM or TEG) have emerged as practical, rapid and sensitive diagnostic modalities. Their role in therapeutic targeting requires further validation. Conventional concepts of traumatic coagulopathy as a late occurring condition in response to iatrogenic haemodilution are redundant. ATC is an endogenous impairment of haemostasis that begins at the moment of injury. Further outcome improvements are possible with better understanding of the process by which this coagulopathy develops and how it may be inhibited.

Stellenwert von Gerinnungsstörungen bei Patienten mit Epistaxis

Epistaxis can have a variety of different local or systemic causes. It is the cardinal symptom of von Willebrand disease (VWD), the most frequent congenital bleeding disorder with a prevalence of approximately 1%. The usual routine coagulation screening tests (PT, APTT, platelet count) are not sufficient to diagnose VWD, factor XIII (FXIII)-deficiency or platelet dysfunction. A prospective study was conducted implementing enhanced coagulation screening for bleeding disorders in a total of 100 inpatients admitted for epistaxis. A bleeding disorder was found in 13%. In eight patients VWD was diagnosed, in six patients FXIII-deficiency was found, and in one patient both. The prevalence of bleeding disorders in patients with epistaxis is higher than in the general population. Epistaxis can be the primary symptom of chronic inflammatory disease or malignant disease. A thorough anamnesis is necessary and in cases of doubt additional testing for underlying disorders is recommended.

Coagulation monitoring and management of anticoagulation during cardiac assist device support

Background The incidence of clinically significant thromboembolic events due to the use of cardiac assist device systems remains high. Despite the considerable advances in cardiac assist device technology, the monitoring and management of the hypercoagulable coagulation status, resulting from foreign surfaces of the assist device system, altered rheologic conditions, and blood stasis in the recipient heart remain a challenge. Moreover septic complications and insufficient anticoagulation are responsible for thromboembolic events. Methods In addition to standard coagulation analysis, functional coagulation tests were performed including the use of a thrombelastographic monitoring system (ROTEG) and a platelet function analyzer (PFA-100). Results Severe biventricular ischemic heart failure developed in a 58-year-old man with acute myocardial infarction and he needed a biventricular assist device for a bridge to cardiac transplantation. Although the patient received acenocoumarol (Sintrom; Novartis Pharma, Vienna, Austria) and acetylsalicylic acid (Aspisol; Bayer AG, Leverkusen, Germany) as usual, ROTEG and the PFA-100 detected hypercoagulability while routine coagulation screening tests showed hypocoagulability. Moreover thrombus formation surrounding the canula of the left ventricular assist device was detected. Antithrombotic therapy with clopidogrel (Plavix) was initiated. Coagulation was closely monitored with modified thrombelastography and the PFA-100 to achieve sufficient but not overwhelming anticoagulation therapy. Three months after biventricular assist device implantation the patient underwent successful transplantation with no major blood loss. Conclusions Thrombelastography should be the standard form of monitoring in such patients to decrease the risk of thromboembolic events and prevent bleeding complications.

The need for routine pre-operative coagulation screening tests (prothrombin time PT/partial thromboplastin time PTT) for healthy children undergoing elective tonsillectomy and/or adenoidectomy

In some medical centers, the routine pre-operative evaluation of healthy children undergoing elective tonsillectomy and/or adenoidectomy (T and A) includes coagulation screening tests (PT, prothrombin Time; PTT, partial thromboplastin time; and INR, international normalized ratio). In this retrospective study, we determined whether there is a positive correlation between prolonged PT/PTT/INR tests in healthy children, with no prior medical history of coagulation problems, and bleeding during surgery and/or bleeding in the month following surgery. We reviewed the records of 416 elective T and A surgeries performed at the Soroka University Medical Center in Beer-Sheva, Israel, over the course of 1999. One hundred and twenty-one (29.1%) patients had preoperative prolonged PT values but only four (3.3%) of these patients experienced light bleeding during surgery. Seven (5.8%) of the 121 patients with prolonged PT tests experienced bleeding episodes during the 1st month subsequent to the surgery. Of the 65 (15.6%) patients who had prolonged pre-operative INR values, only three (4.6%) experienced light bleeding during surgery. Two (3.1%) patients with prolonged INR values experienced light bleeding during the 1st month subsequent to surgery. Sixty-one (14.7%) patients had prolonged first preoperative PTT values, only five of whom (8.2%) experienced light bleeding during surgery. Two (3.3%) of the 61 with prolonged PTT values experienced light bleeding during the 1st month subsequent to surgery. We therefore concluded that pre-operative coagulation screening tests provide low sensitivity and low bleeding predictive value. As such, routine coagulation tests before T &A are not indicated unless a medical history of bleeding tendency is suspected.

Coagulation Parameters in Maternal and Cord Blood at Delivery

A wide range of hemostatic variables were studied in 300 maternal/neonatal pairs at the time of delivery and also in 375 healthy nonpregnant women who served as controls. There was significant prol...

Failure of Routine Coagulation Screening Tests to Detect Heterozygous State of Bovine Factor XI Deficiency.

In a survey of coagulation, biochemical and hematological parameters in cattle homozygous (deficient), heterozygous (carrier) and non-affected (normal) for Factor XI deficiency, only the Activated Partial Thromboplastin Time (APTT) results correlated with plasma Factor XI activity levels. The APTT results and the thrombokinetics for the deficient animals were markedly different from the results of either the carrier or normal animals. However, the APTT assay was shown not to be sufficiently sensitive to differentiate between the normal and carrier state for the coagulation disorder. Not only was there no statistical difference between the mean APTT results for the normal and carrier animals, but the thrombokinetics for fibrin clot formation for the two groups were also similar.

Evidence for intravascular coagulation in systemic onset, but not polyarticular, juvenile rheumatoid arthritis.

After observing a child with systemic onset juvenile rheumatoid arthritis (S-JRA) who developed purpura fulminans in association with disseminated intravascular coagulation, with subsequent gangrene and autoamputation, we undertook a prospective study of coagulation parameters in children with JRA. Ten consecutive children with S-JRA, 10 children with rheumatoid factor-negative, polyarticular juvenile rheumatoid arthritis (P-JRA), and 10 age- and sex-matched controls were studied. Routine coagulation screening tests were performed, as were tests for plasma fibrinopeptide A (a sensitive measure of intravascular thrombin generation), factor VIII-related antigen (an endothelial cell protein), and platelet factor 4 (a platelet-secreted protein). Our studies suggest that activation of intravascular coagulation is common in systemic onset JRA, but not in rheumatoid factor-negative, polyarticular disease. The coagulopathy may cause severe morbidity. In addition, marked elevations of plasma factor VIII-related antigen suggest perturbation of endothelial cells and vascular involvement in S-JRA, but not in P-JRA. Normal ranges of platelet factor 4 indicate that intravascular platelet consumption does not occur in either type of JRA, despite the thrombocytosis common in both.