Assessment of the Validity of the INR System for Patients with Liver Impairment

Early prediction of decompensation (EPOD) score: Non-invasive determination of cirrhosis decompensation risk

BACKGROUND & AIMS

Decompensation is a hallmark of disease progression in cirrhotic patients. Early detection of a phase transition from compensated cirrhosis to decompensation would enable targeted therapeutic interventions potentially extending life expectancy. This study aims to (a) identify the predictors of decompensation in a large, multicentric cohort of patients with compensated cirrhosis, (b) to build a reliable prognostic score for decompensation and (c) to evaluate the score in independent cohorts.

METHODS

Decompensation was identified in electronic health records data from 6049 cirrhosis patients in the IBM Explorys database training cohort by diagnostic codes for variceal bleeding, encephalopathy, ascites, hepato-renal syndrome and/or jaundice. We identified predictors of clinical decompensation and developed a prognostic score using Cox regression analysis. The score was evaluated using the IBM Explorys database validation cohort (N = 17662), the Penn Medicine BioBank (N = 1326) and the UK Biobank (N = 317).

RESULTS

The new Early Prediction of Decompensation (EPOD) score uses platelet count, albumin, and bilirubin concentration. It predicts decompensation during a 3-year follow-up in three validation cohorts with AUROCs of 0.69, 0.69 and 0.77, respectively, and outperforms the well-known MELD and Child-Pugh score in predicting decompensation. Furthermore, the EPOD score predicted the 3-year probability of decompensation.

CONCLUSIONS

The EPOD score provides a prediction tool for the risk of decompensation in patients with cirrhosis that outperforms well-known cirrhosis scores. Since EPOD is based on three blood parameters, only, it provides maximal clinical feasibility at minimal costs.

Targeting von Willebrand factor in liver diseases: A novel therapeutic strategy?

Acute and chronic liver disease are associated with substantial alterations in the hemostatic system. Evidence from both experimental and clinical studies suggests that anticoagulants slow the progression of liver disease. Efficacy of those anticoagulant drugs is, in part, attributed to a reduction of microthrombi formation within the liver. Although anticoagulant drugs show promising results, bleeding risk associated with these drugs is an obvious drawback, particularly in patients with a complex coagulopathy driven by decreased liver function. Identifying therapies that reduce intrahepatic thrombosis with minimal bleeding risk would significantly advance the field. Among the hemostatic alterations observed in patients are substantially increased levels of the platelet-adhesive protein von Willebrand factor (VWF). In contrast, levels of A Disintegrin and Metalloproteinase with Thrombospondin motifs, the enzyme that regulates VWF activity, are significantly reduced in patients with liver disease. Highly elevated VWF levels are proposed to accelerate intrahepatic thrombus formation and thus be a driver of disease progression. Strong clinical evidence suggesting a link between liver disease and changes in VWF is now being matched by emerging mechanistic data showing a detrimental role for VWF in the progression of liver disease. This review focuses on clinical and experimental evidence supporting a connection between VWF function and the progression of acute and chronic liver diseases. Furthermore, with the recent anticipated approval of several novel therapies targeting VWF, we discuss potential strategies and benefits of targeting VWF as an innovative therapy for patients with liver disease.

Anticoagulation in patients with advanced liver disease: an open issue

Liver disease has been long considered as a risk factor for bleeding for the presence of prolongation of global tests of clotting activation and low platelet count. For this reason, the use of anticoagulants in patients with liver disease and an indication to anticoagulation, such as atrial fibrillation of venous thrombosis, has been poorly considered. Furthermore, recent studies underscored the fact that patients with chronic liver disease may experience thrombosis in portal as well as systemic circulation and treatment with anticoagulants should be considered. The introduction of direct oral anticoagulants has increased therapeutic options for thromboprophylaxis; however, evidence on their safety and efficacy in specific populations, such as patients with liver disease, is still scarce and needs further investigation. Thus, atrial fibrillation patients with coexistent liver disease have been excluded from clinical trials with direct oral anticoagulants. Here, we provide an overview on mechanisms of thrombosis in patients with advanced chronic liver disease and a summary of evidence on the use of oral anticoagulants in patients with liver disease and portal vein thrombosis or atrial fibrillation.

Incidence of bleeding in patients with atrial fibrillation and advanced liver fibrosis on treatment with vitamin K or non-vitamin K antagonist oral anticoagulants

OBJECTIVES

To investigate the incidence of bleeding events in atrial fibrillation (AF) patients treated with vitamin K (VKAs) or non-vitamin K antagonist oral anticoagulants (NOACs) screened for the presence of liver fibrosis (LF).

BACKGROUND

Previous studies provided conflicting results on bleeding risk in AF patients with liver disease on VKAs, and no data on NOACs in this setting are available.

METHODS

Post-hoc analysis of a prospective, observational multicentre study including 2330 AF outpatients treated with VKAs (n = 1297) or NOACs (n = 1033). Liver damage was quantified by the FIB-4 score (>3.25), a validated marker of LF. The primary endpoint was the incidence of any bleeding, according to ISTH classification.

RESULTS

A high FIB-4 was present in 129 (5.5%) patients: 77 (5.9%) on VKA and 52 (5.0%) on NOACs (p = 0.344). During follow-up, 357 (15.3%) patients experienced a bleeding: 261 (80 major and 180 minor) with VKAs (7.2%/year), and 96 (40 major and 56 minor) with NOACs (6.4%/year). In VKA-treated patients, but not in those on NOACs, FIB-4 >3.25 was associated with higher major bleeding (14.3% vs. 5.6%, log-rank test p < 0.001). Multivariable Cox regression model showed that FIB-4 was associated with major bleeding only in VKA-treated patients (HR: 3.075, 95% CI 1.626-5.818, p = 0.001). On multivariable analysis, FIB-4 was not significantly associated with CVEs neither in VKA or NOAC-treated patients.

CONCLUSION

We found a significant association between LF and major bleedings in AF patients treated with VKA, which was not evident in patients on NOACs.

MELD score as a predictor of mortality, length of hospital stay, and disease burden: A single-center retrospective study in 39,323 inpatients

The laboratory-based model for end-stage liver disease (MELD) score reflects the function of the kidney, liver, and extrinsic coagulation pathway and might be used as a general prognostic tool for the assessment of patients. We therefore aimed to investigate a potential association of the MELD score with mortality, length of hospital stay (LOS), and disease burden in a general patient population.We performed a retrospective observational study at a tertiary referral center. From January 2012 through December 2013, all consecutive inpatients aged 18 years were eligible for the study; patients with missing MELD parameters on hospital admission and/or treatments influencing the international normalized ratio, that is, novel oral anticoagulants and vitamin K antagonists, were excluded. The MELD score on hospital admission was calculated retrospectively. The primary outcome measure was in-hospital all-cause mortality; secondary outcome measures were LOS and the number of comorbidities.A total of 39,323 inpatients were included in the final analysis. On admission, MELD scores of 15 to 19, 20 to 29, and ≥30 points (reference <15 points) showed increased hazard ratios (HRs) for in-hospital mortality in uni- and multivariable analysis with an adjusted HR of 2.52 (95% confidence interval [CI], 1.81-3.49; P < .001), 2.70 (95% CI, 1.89-3.84; P < .001), and 8.00 (95% CI, 3.91-16.39; P < .001), respectively. Increased MELD scores of 15 to 19, 20 to 29, and ≥30 points were positively associated with LOS and the number of comorbidities in uni- and multivariable analysis.In our study population consisting of adult inpatients, the MELD score on hospital admission was significantly associated with mortality, LOS, and the number of comorbidities. We suggest to prospectively validate the MELD score in inpatients as part of clinical decision support systems.

The Utility of Viscoelastic Testing in Patients Undergoing IR Procedures

Whole-blood viscoelastic testing can identify patient-specific coagulation disturbances, allowing for targeted repletion of necessary coagulation factors and differentiation between coagulopathy and surgical bleeding that requires intervention. Viscoelastic testing complements standard coagulation tests and has been shown to decrease transfusion requirements and improve survival in bleeding patients. Viscoelastic testing also can be used to predict bleeding and improve the care of patients undergoing interventional radiology (IR) procedures.

A survey of coagulation laboratory practices and satisfaction ratings of member laboratories of the Thailand National External Quality Assessment Scheme for blood coagulation

INTRODUCTION

The Thailand National External Quality Assessment Scheme (NEQAS) for blood coagulation was established in 2005. The objective of this study was to collect data of coagulation laboratory practices and satisfaction of NEQAS member.

METHODS

Two hundred seventy-six questionnaires were sent to laboratories that are members of NEQAS to obtain data relating to coagulation laboratory practice and satisfaction in 2014. Data from this survey were compared with data from the survey conducted in 2005 to evaluate levels of improvement.

RESULTS

Of 276 questionnaires sent, 212 (76.8%) were returned. Improvements were characterized by the number of laboratories that (i) decreased use of 3.8% sodium citrate as anticoagulant; (ii) implemented use of at least two control levels for internal quality control; and (iii) implemented reporting of reference values with results, as well as establishing their own reference range and using geometric mean as the denominator for international normalized ratio calculation. For overall satisfaction, 179 of 206 (86.9%) participant laboratories reported being satisfied or very satisfied.

CONCLUSION

Improvements in coagulation laboratory practices in Thailand were observed in every step of the total testing process. However, additional improvements are still needed, such as determination and use of a local reference range.

Effect of diseases on response to vitamin K antagonists

INTRODUCTION

The purpose of this review article is to summarize the literature on diseases that are documented to have an effect on response to warfarin and other VKAs.

METHODS

We searched the English literature from 1946 to September 2015 via PubMed, EMBASE, and Scopus for the effect of diseases on response vitamin K antagonists including warfarin, acenocoumarol, phenprocoumon, and fluindione.

DISCUSSION

Among many factors modifying response to VKAs, several disease states are clinically relevant. Liver disease, hyperthyroidism, and CKD are well documented to increase response to VKAs. Decompensated heart failure, fever, and diarrhea may also elevate response to VKAs, but more study is needed. Hypothyroidism is associated with decreased effect of VKAs, and obese patients will likely require higher initial doses of VKAs.

CONCLUSION

In order to minimize risks with VKAs while ensuring efficacy, clinicians must be aware of the effect of disease states when prescribing these oral anticoagulants.

Portal vein thrombosis: When to treat and how?

Portal vein thrombosis is an unusual thrombotic condition not frequently seen in the general population; however, it has a higher prevalence in special circumstances such as in liver cirrhosis and hepatic or pancreatic malignancy. It also can be associated with significant morbidity and mortality. In this review, we discuss the current data available to guide therapy in the setting of different associated co-morbidities, hypercoagulable states, and associated thrombosis of the remaining splanchnic circulation. We discuss indications for anticoagulation, including the choice of anticoagulants, as well as the role of conservative 'wait and watch' and invasive therapies, such as thrombolysis, thrombectomy, and transjugular intrahepatic portosystemic shunt.

Monitoring anticoagulation in patients with an unreliable prothrombin time/international normalized ratio: factor II versus chromogenic factor X testing

The international normalized ratio (INR) can be unreliable in patients with lupus anticoagulants (LACs) or other conditions affecting baseline testing. Alternative methods to assess anticoagulation on warfarin through measures of vitamin K-dependent factor activity by clot based or chromogenic assays may be necessary. In this patient population, the ideal method is unknown. Thirty-six patients stable on warfarin with LAC or unreliable INR testing had an INR, a prothrombin time-based clotting assay for factor II (FII) activity, and a chromogenic assay for factor X (CFX) activity were performed simultaneously. Eighty-nine sets of measurements were obtained of which 83 sets included all three assays. CFX and FII levels were well correlated (r = 0.92) in all patients and in 26 patients with a documented antiphospholipid antibody (r = 0.93). Parallel testing was seen in 99% of FII assays. Sixty-one percent of CFX and 57% of FII were within the therapeutic range. In 32 CFX and FII pairs wherein assessment of anticoagulation was discordant, 16 CFX agreed with INR and 13 FII agreed with INR (McNemar's, χ = 0.14, P = 0.7). The number of times tests were discrepant was not statistically different between CFX and FII (P = 0.36). CFX and FII activity are well correlated in patients that require alternative monitoring of warfarin. Either test can be used in this population.

Hepatic coagulopathy-intricacies and challenges; a cross-sectional descriptive study of 110 patients from a superspecialty institute in North India with review of literature

Hemostatic defect in chronic liver disease (CLD) is complex involving opposing factors of primary hemostasis, coagulation, and fibrinolysis. The concept of causal relationship between abnormal tests and clinical bleeding is unclear. This study was undertaken to evaluate and correlate clinical bleeding and the commonly used laboratory tests for hemostasis in CLD patients including the subgroup of acute on chronic liver failure (ACLF) patients and test the reproducibility of international normalized ratio (INR) using different reagents. This was a cross-sectional descriptive study wherein clinical records and laboratory data from 110 patients (95 CLD, 15 ACLF) over a 6-month period were analysed. Variceal bleeding (33.3%) was the commonest followed by mucosal/skin bleeds (5.4%). Thrombocytopenia seen in 70.9% patients was mostly mild (48.2%) to moderate (14.5%). Prothrombin time (PT) prolongation was seen in 81.8% with significant variation in PT/INR using different reagents. Adverse outcome in the form of disseminated intravascular coagulation, septic shock or death was seen in 13.6% patients (eight ACLF and seven CLD). There was no correlation of bleeding with prolonged PT/INR, decreased platelet count and adverse clinical outcome. However, individually, there was significant but weak correlation between variceal bleeding and lower platelet count and superficial bleeding and prolonged PT. Correction of PT/INR post-fresh frozen plasma was significant but platelet count postplatelet concentrate transfusion was not. ACLF patients compared with CLD patients had greater PT prolongation and adverse outcome but no increase in bleeding. Routine tests, although globally deranged inadequately reflect haemostatic imbalance in CLD and poorly predict bleeding risk.

Pathology consultation on anticoagulation monitoring: factor X-related assays

OBJECTIVES

To review various anticoagulation therapies and related laboratory monitoring issues, with a focus on factor X-related chromogenic assays.

METHODS

A case-based approach is used to review pertinent published literatures and product inserts of anticoagulation drugs and to look back on clinical use of factor X-related chromogenic assays.

RESULTS

The number of anticoagulants available to clinicians has increased greatly in the past decade. Whether and how these anticoagulants should be monitored are areas of uncertainty for clinicians, which can lead to misuse of laboratory assays and suboptimal patient management. Factor X-related assays are of particular concern because of the similar and often confusing test names. Based on a common clinical case scenario and literature review regarding anticoagulant monitoring, an up-to-date discussion and review of the various factor X-related assays are provided, focusing on the differences in test designs and clinical utilities between the chromogenic anti-Xa and chromogenic factor X activity assays.

CONCLUSIONS

Anticoagulation therapy and related laboratory monitoring are rapidly evolving areas of clinical practices. A good knowledge of relevant laboratory assays and their clinical applications is necessary to help optimize patient care.

Transiently increased variation between a Point-of-Care and laboratory INR method after a long period of correlation: a case study demonstrating the need for ongoing correlation of POC with the central laboratory

OBJECTIVES

To perform long-term comparison between laboratory Stago and Point-of-Care (POC) i-STAT methods for determining the international normalized ratio (INR).

METHODS

This was a multicenter method comparison of patient INR results and factors related to performance variance.

RESULTS

For 5 years, the assays demonstrated close patient correlation within and above the 3.5 INR therapeutic range cutoff (bias, 0.23 INR units). Patient results above 3.5 INR were bimodal, with 60% demonstrating an i-STAT INR bias of less than 0.5. Several patient conditions were associated with the presence of a higher i-STAT bias. In year 6, a broader range i-STAT bias developed, increasing to 0.73 INR units. The increased bias persisted for 3 years, then returned to initial levels following i-STAT adjustments. The substantial increase in i-STAT bias after a long period of stability was partly corrected by renewed correlation to the international reference preparation. Additional assay drift is discussed in relation to thromboplastin reagents and other testing variables.

CONCLUSIONS

This study emphasizes the need for continual laboratory correlation with POC devices and caution in using published comparisons.

The international normalized ratio according to Owren in liver disease: interlaboratory assessment and determination of international sensitivity index

INTRODUCTION

The international normalized ratio (INR) is used to prioritize liver disease patients for transplantation. Previous studies have shown high interlaboratory variability in Quick-based INR determinations in samples of patients with liver disease. We assessed Owren-based INR reagents for analyzing INR in patients with liver disease. Further, we determined the difference between international sensitivity index (ISI) for patients on vitamin K antagonists (ISIVKA) and ISI for patients with liver disease (ISIliver).

PATIENTS AND METHODS

Twenty patients with liver disease were included, 10 with INR 1.8-3.6 (group A1) and 10 with INR 1.2-1.5 (group C1). Plasma from these patients was analyzed for Owren-based INR in eight Swedish laboratories using either of following reagents: SPA+, Owrens PT or Nycotest PT. To determine ISI liver, the reference thromboplastin RBT/05 and additional 41 patients with liver disease and 20 normal controls were included. ISIVKA was determined according to the WHO procedure. The difference between the ISIVKA and ISIliver was calculated.

RESULTS

The coefficients of variance for the Owren based INR methods were 6.2% in group A1, 3.9 % in group C1 and 5.3% for all patients. The difference between ISIVKA and ISIliver were -0.4%, -0.7% and -0.2% for SPA+, Owrens PT and Nycotest PT respectively.

CONCLUSIONS

Interlaboratory variation in INR analyses according to Owren in patients with liver disease is low and the difference between ISIVKA and ISIliver is below 10% with this method. ISIVKA can therefore be used in the INR calibration, for the Owren reagents studied, when analyzing plasma from patients with liver disease.

Important predictor of mortality in patients with end-stage liver disease

Prognosis is an essential part of the baseline assessment of any disease. For predicting prognosis of end-stage liver disease, many prognostic models were proposed. Child-Pugh score has been the reference for assessing the prognosis of cirrhosis for about three decades in end-stage liver disease. Despite of several limitations, recent large systematic review showed that Child-Pugh score was still robust predictors and it's components (bilirubin, albumin and prothrombin time) were followed by Child-Pugh score. Recently, Model for end-stage liver disease (MELD) score emerged as a "modern" alternative to Child-Pugh score. The MELD score has been an important role to accurately predict the severity of liver disease and effectively assess the risk of mortality. Due to several weakness of MELD score, new modified MELD scores (MELD-Na, Delta MELD) have been developed and validated. This review summarizes the current knowledge about the prognostic factors in end-stage liver disease, focusing on the role of Child-Pugh and MELD score.

Portal vein thrombosis: a clinician-oriented and practical review

With advances in modern imaging techniques, portal vein thrombosis (PVT) is being increasingly diagnosed. It has a wide ranging clinical spectrum from being an asymptomatic state to a potentially life-threatening situation. It is not unusual to find it as an incidental finding in the abdominal imagings done for other reasons. It is commonly associated with cirrhosis and abdominal malignancies and also has a strong association with prothrombotic disorders. It is often difficult for the clinicians to decide whether PVT is acute or chronic. This poses great challenges to its management strategies that include anticoagulants, thrombolysis, and surgical options. Timely diagnosis and appropriate management have great bearings on its outcomes of morbidity and mortality. In this clinician-oriented review, we have provided a concise review of clinical aspects of PVT and discussed various management strategies while addressing the common questions that come to a physician's mind dealing with such a patient.

Management of anticoagulation for portal vein thrombosis in individuals with cirrhosis: a systematic review

Non-neoplastic portal vein thrombosis (PVT) is an increasingly recognized complication of liver cirrhosis. It is often diagnosed fortuitously and can be either partial or complete. The clinical significance of PVT is not obvious except in some situations such as when patients are on the waiting list for liver transplantation. The only known therapy is anticoagulation which has been shown to permit the disappearance of thrombosis and to prevent further extension. Anticoagulation is a challenging therapy in individuals with liver cirrhosis because of the well-recognized coagulation abnormalities observed in that setting and because of the increased risk of bleeding, especially from gastrointestinal tract caused by portal hypertension. We herein review the current knowledge on that topic in order to highlight the advantages and disadvantages of the currently proposed therapeutic attitudes in face of the diagnosis of PVT in individuals with cirrhosis.

A revised model for end-stage liver disease optimizes prediction of mortality among patients awaiting liver transplantation

BACKGROUND & AIMS

The Model for End Stage Liver Disease (MELD) was originally developed based on data from patients who underwent the transjugular intrahepatic portosystemic shunt procedure. An updated MELD based on data from patients awaiting liver transplantation should improve mortality prediction and allocation efficiency.

METHODS

Wait-list data from adult primary liver transplantation candidates from the Organ Procurement and Transplantation Network were divided into a model derivation set (2005-2006; n=14,214) and validation set (2007-2008; n=13,945). Cox regression analysis was used to derive and validate an optimized model that updated coefficients and upper and lower bounds for MELD components and included serum levels of sodium. Main outcomes measure was ability to predict 90-day mortality of patients on the liver transplantation wait list.

RESULTS

Optimized MELD score updated coefficients and implemented new upper and lower bounds for creatinine (0.8 and 3.0 mg/dL, respectively) and international normalized ratio (1 and 3, respectively). Serum sodium concentrations significantly predicted mortality, even after adjusting for the updated MELD model. The final model, based on updated fit of the 4 variables (ie, bilirubin, creatinine, international normalized ratio, and sodium) had a modest yet statistically significant gain in discrimination (concordance: 0.878 vs 0.865; P<.01) in the validation dataset. Utilization of the new score could affect up to 12% of patients (based on changed score for 459 of 3981 transplants in the validation set).

CONCLUSIONS

Modification of MELD score to update coefficients, change upper and lower bounds, and incorporate serum sodium levels improved wait-list mortality prediction and should increase efficiency of allocation of donated livers.

The International Normalized Ratio (INR) in the MELD score: problems and solutions

The Model for End-Stage Liver Disease (MELD) score is widely used to prioritize patients for liver transplantation. One of the pitfalls of the MELD score is the interlaboratory variability in all three components of the score (INR, bilirubin, creatinine). The interlaboratory variability in the INR has the largest impact on the MELD score, with a mean difference of around 5 MELD points in most studies. During the 3rd conference on Coagulopathy and Liver disease, a multidisciplinary group of scientists and physicians discussed possible solutions for the INR problem in the MELD score with the intention to provide a constructive contribution to the international debate on this issue. Here we will discuss possible solutions and highlight advantages and disadvantages.

Patient Factors That Influence Warfarin Dose Response

Warfarin has long been the mainstay of oral anticoagulation therapy for the treatment and prevention of venous and arterial thrombosis. The narrow therapeutic index of warfarin, and the complex number of factors that influence international normalized ratio (INR) response, makes optimization of warfarin therapy challenging. Determination of the appropriate warfarin dose during initiation and maintenance therapy requires an understanding of patient factors that influence dose response: age, body weight, nutritional status, acute and chronic disease states, and changes in concomitant drug therapy and diet. This review will examine specific clinical factors that can affect the pharmacokinetics and pharmacodynamics of warfarin, as well as the role of pharmacogenetics in optimizing warfarin therapy.

Thromboplastin standards

The Prothrombin Time (PT) test is used for monitoring of treatment with Vitamin K-antagonists (VKA). The result of the PT test should be expressed as the International Normalized Ratio (INR). Calculation of INR is based on the availability of International Standards (IS) for thromboplastin and a calibration model. Calibration of a new PT test system is performed with the appropriate IS and fresh plasma samples of healthy (normal) volunteers and patients treated with VKA. The calibration model is based on the assumption of a linear relationship between the log(PT)'s obtained with the new PT system and the reference IS for both normal and patients' samples. Patients' samples for calibration should be selected by rejecting samples beyond the 1.5-4.5 INR range. Outliers should be rejected defined as points with a perpendicular distance greater than three residual standard deviations from the line of relationship. Selection of patients' samples and rejection of outliers result in a reduction of the between-laboratory variation of calibration. In addition to monitoring of VKA, the PT is used for management of patients with chronic liver disease. Likewise, INR(liver) should be based on calibration with an IS using samples from patients with chronic liver disease.

Systematic review: portal vein thrombosis in cirrhosis

BACKGROUND

As current imaging techniques in cirrhosis allow detection of asymptomatic portal vein thrombosis during routine ultrasonography, more patients with cirrhosis are diagnosed with portal vein thrombosis. Although a consensus on noncirrhotic extra-hepatic portal vein thrombosis has been published, no such consensus exists for portal vein thrombosis with cirrhosis.

AIM

To perform a systematic review of nonmalignant portal vein thrombosis in cirrhosis in terms of prevalence, pathogenesis, diagnosis, clinical course and management.

METHODS

Studies were identified by a search strategy using MEDLINE and EMBASE.

RESULTS

Portal vein thrombosis is encountered in 10-25% of cirrhotics. In terms of pathophysiology, cirrhosis is no longer considered a hypocoagulable state; rather than a bleeding risk in cirrhosis, various clinical studies support a thrombotic potential. Clinical findings of portal vein thrombosis in cirrhosis vary from asymptomatic disease to a life-threatening condition at first presentation. Optimal management of portal vein thrombosis in cirrhosis is currently not addressed in any consensus publication. Treatment strategies most often include the use of anticoagulation, while thrombectomy and transjugular intrahepatic portosystemic shunts are considered second-line options.

CONCLUSIONS

Portal vein thrombosis in cirrhosis has many unresolved issues, which are often the critical problems clinicians encounter in their everyday practice. We propose a possible research agenda to address these unresolved issues.

Prothrombin time and partial thromboplastin time assay considerations

Prothrombin times and activated partial thromboplastin times have long been used as tests of overall ("global") clotting function. Laboratory coagulation testing issues should be at the forefront of the reader's consciousness whenever critically evaluating and extrapolating published study conclusions reliant on the results of these tests. Thus, this article reviews laboratory issues and known variables influencing prothrombin time and partial thromboplastin time results and international normalized ratio determinations.

Point-of-care coagulation monitors calibrated for the international normalized ratio for cirrhosis (INRliver) can help to implement the INRliver for the calculation of the MELD score

BACKGROUND/AIMS

The MELD defines a score used to prioritize patients awaiting liver transplantation and includes results for bilirubin, creatinine and PT expressed as INR. It is assumed that the MELD for individual patients is the same regardless of the laboratory method used for testing, thus ensuring parity of organ allocation. Previous studies showed that the INR calibrated for patients on vitamin K antagonists (INR(vka)) does not normalize results across thromboplastins, whereas an alternative calibration called INR(liver) does. However, implementation of INR(liver) calibration for thromboplastins is difficult in practice. This study aimed to assess whether easy-to-run whole-blood coagulation monitors (widely used for patients on VKA) can be calibrated to measure efficiently the INR(liver) and minimize the interlaboratory variability.

METHODS

PT values for 61 cirrhotic patients were measured on native-blood with 2 monitors calibrated in terms of INR(vka). PTs for these subjects were also measured with a WHO-standard for thromboplastin. Paired-PTs with the monitors and the standard were subsequently used to calibrate the monitors in terms of INR(liver). INR(vka) and INR(liver) were then compared to assess for statistical significance.

RESULTS

The mean INR(vka) obtained with the monitors and the standard were significantly different (p<0.001). Conversely, the corresponding INR(liver) were not.

CONCLUSIONS

The INR(liver) calibration as previously described for thromboplastins works also for the easy-to-run whole-blood coagulation monitors. Once the monitors are calibrated by the manufacturer in terms of INR(liver) they could be used as near-patient-testing devices directly by the personnel of liver units making the determination of the INR for patients awaiting liver transplantation much easier and standardized.

Comparison and improvement of MELD and Child-Pugh score accuracies for the prediction of 6-month mortality in cirrhotic patients

BACKGROUND/GOALS

Superiority of the model for end-stage liver disease (MELD) over the Child-Pugh score for the prediction of outcome in patients with chronic liver disease is still debated. The main objective of this prospective study was to evaluate the accuracy of the Child-Pugh score, the MELD, and the new score, MELD-Na, combining MELD and serum sodium (Na), for the prediction of 6-month mortality in cirrhotic patients.

STUDY

In all, 308 consecutive cirrhotic patients were included. Child-Pugh score, MELD, and MELD-Na were calculated at the inclusion.

RESULTS

In all, 154 patients (50.0%) had decompensated cirrhosis. Forty-five patients died during the 6-month follow-up: 3 in the subgroup of compensated cirrhosis and 42 in the decompensated subgroup (1.9% vs. 27.3%, P<10(-3)). Area under the receiver operating characteristic curve for the prediction of 6-month mortality of Child-Pugh score, MELD, and MELD-Na were, respectively, in the whole population: 0.882, 0.866, and 0.887 (P=NS), and in the subgroup of decompensated cirrhosis: 0.796, 0.800, and 0.833 (P=NS). MELD-Na had the highest accuracy but the difference reached statistical significance only with the Child-Pugh score in the subgroup of patients with decompensated cirrhosis (79.9% vs. 68.0%, P=0.006). The combination of Child-Pugh score or MELD with other variables reflecting the circulatory dysfunction observed in end-stage liver disease significantly improved the accuracy of these 2 models.

CONCLUSIONS

Child-Pugh score remains a simple and effective tool for the prognostic assessment of cirrhotic patients at bedside and can still be used in clinical practice. MELD, and especially MELD-Na, should be reserved for patients with decompensated cirrhosis.

Prognostic indices for Budd-Chiari syndrome: valid for clinical studies but insufficient for individual management

OBJECTIVES

Several prognostic indices (PIs) have been proposed for Budd-Chiari syndrome (BCS). However, patient characteristics, causal factors, and treatment outcomes have changed since these indices have been elaborated. Validation in a recent patient population and comparison of predictive accuracy between these PIs are needed.

METHODS

A database of 96 BCS patients diagnosed between 1995 and 2005 was analyzed. Cox survival models were fitted with time to liver transplantation or death, and time to invasive therapy or death, as end points. The prognostic values of known indices (Child-Pugh score, model for end-stage liver disease (MELD), Clichy, Rotterdam BCS index, New Clichy, and BCS-TIPS (transjugular intrahepatic portosystemic shunt)) at diagnosis were assessed in Cox models using the chi-square test, the Kent and O'Quigley measure of dependence, and unrestricted bootstrapping analysis. Areas under receiver operating characteristic curves (AUROCs) were built for both end points and compared.

RESULTS

All prognostic indices, except BCS-TIPS, were significant predictors of transplant-free and invasive therapy-free survival. However, only 31 and 37% of the variance in transplant-free and invasive therapy-free survival, respectively, were explained by the best performing indices. For transplant-free survival, AUROCs were < 0.70. For invasive therapy-free survival, AUROCs were < 0.80. For both end points, BCS-TIPS PI AUROCs were significantly lower than others.

CONCLUSIONS

Most PIs are valid for transplant-free survival and invasive therapy-free survival in a population of current BCS patients, and thus can be used for stratification in clinical studies. However, predictive accuracy is insufficient to be used for individual patients.

The asymptomatic outpatient with abnormal liver function tests

Traditionally, the constellation of biochemistry tests including liver enzymes, total bilirubin, and hepatic synthetic measures (prothrombin time (PT) and serum albumin level) are referred to as liver function tests (LFTs). Abnormal LFTs can be encountered during primary health care visits, routine blood donation, and insurance screening. A reported 1% to 4% of asymptomatic patients exhibit abnormal LFTs, leading to a sizeable number of annual consultations to a gastroenterology and/or hepatology practice. A cost-effective and systematic approach is essential to the interpretation of abnormal LFTs. A review of pattern of abnormal LFTs, detailed medical history, and a comprehensive physical examination help establish a foundation for further individualized testing. Further investigation often involves biochemical testing for disease-specific markers, radiographic imaging, and even consideration of a liver biopsy. In the following account, markers of hepatic injury are reviewed followed by a discussion on an approach to various patterns of abnormal LFTs in an asymptomatic patient.

International normalized ratio of prothrombin time in the model for end-stage liver disease score: an unreliable measure

The current basis for deceased donor liver allocation is the Model for End-stage Liver Disease (MELD) score, which is an objective means of predicting 90-day patient survival. Although the MELD system is a vast improvement over the prior allocation scheme, published studies have refuted the United Network for Organ Sharing statement that "the MELD and PELD [Pediatric End-stage Liver Disease] formulas are simple, objective and verifiable and yield consistent results whenever the score is calculated." In particular, wide inter-laboratory variation exists in the most heavily weighted MELD determinant, the international normalized ratio (INR). Whether this variation impacts the equitable distribution of deceased donor livers is unclear. However, the current technique for measuring the INR has the potential to detract from the expressed purpose of MELD-based allocation, which is to prioritize liver transplant candidates across the country with parity, using an objective scoring system.

The coagulopathy of cirrhosis assessed by thromboelastometry and its correlation with conventional coagulation parameters

BACKGROUND

Thromboelastometry allows continuous registration of the blood viscoelastic changes upon activation by cephaline or tissue-factor plus calcium-chloride. The technique is used as a near-patient-testing device to guide transfusion in cardiac surgery or liver transplantation and less to investigate hemostasis in acquired or congenital coagulopathies.

AIMS

(i) Review of the coagulopathy associated with cirrhosis and (ii) report on its investigation by thromboelastometry in comparison with conventional coagulation parameters.

METHODS

We investigated citrated blood samples from 51 adult cirrhotics for the following thromboelastometry parameters: coagulation-time (CT), clot-formation-time (CFT), maximum-clot-firmness (MCF).

RESULTS

Relatively few patients [14/51(27%)] were identified as abnormal by CT; in contrast, a greater proportion were identified by the CFT [41/51(80%)] or MCF [39/51(76%)]. CFT and MCF were correlated with the platelet-count, antithrombin and fibrinogen. Prothrombin time (PT) was correlated with CFT and MCF. None of the coagulation parameters were correlated with CT. The correlation of the Child-Pugh-score (taken as index of severity) versus MCF or PT was -0.457(p < 0.001) or 0.484(p < 0.001), suggesting MCF as a suitable prognostic index. CFT and MCF, but not CT obtained ROC curves that were useful to distinguish patients from healthy individuals.

CONCLUSIONS

Thromboelastometry, currently used to assist liver transplantation is also suitable for investigating stable cirrhosis. CFT and MCF are the most interesting parameters to be considered for future clinical studies needed to assess their value as measures of bleeding-risk and prognosis in this category of patients.

Interlaboratory variability in assessment of the model of end-stage liver disease score

BACKGROUND

The model of end-stage liver disease (MELD) score is nowadays widely used to prioritize patients for liver transplantation.

AIMS

To assess the contribution of the individual components of the MELD score in interlaboratory variability.

METHODS

We sent 15 samples from patients listed for liver transplantation to seven different European laboratories who were asked to measure all three variables. In addition, 10 samples from patients on oral anticoagulant treatment were sent to the same labs for the international normalised ratio (INR) measurement.

RESULTS AND CONCLUSIONS

In all 15 samples, a substantial and clinically relevant variation in the calculated MELD score was observed between laboratories. The mean difference in the MELD score between the highest- and the lowest-scoring laboratory was 4.8. The variation in creatinine measurements resulted in differences of up to three MELD points in a single patient when comparing the highest and the lowest scoring lab. The variation in bilirubin measurements only accounted for a difference of one point between the highest- and the lowest-scoring laboratory, but the variation in INRs resulted in differences of 2 to 12 MELD points. MELD scores or INR values were not substantially different in laboratories that used the Owren instead of the more widely used Quick methodology for INR measurements. The variability in the INR in patients on oral anticoagulants was substantially less as compared with the variability in patients with liver disease. In conclusion, we observed a large interlaboratory variation in the MELD score. This variation in the MELD score is primarily caused by the INR.

Pharmacology and management of the vitamin K antagonists: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition)

This article concerning the pharmacokinetics and pharmacodynamics of vitamin K antagonists (VKAs) is part of the American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition). It describes the antithrombotic effect of the VKAs, the monitoring of anticoagulation intensity, and the clinical applications of VKA therapy and provides specific management recommendations. Grade 1 recommendations are strong and indicate that the benefits do or do not outweigh the risks, burdens, and costs. Grade 2 recommendations suggest that the individual patient's values may lead to different choices. (For a full understanding of the grading, see the "Grades of Recommendation" chapter by Guyatt et al, CHEST 2008; 133:123S-131S.) Among the key recommendations in this article are the following: for dosing of VKAs, we recommend the initiation of oral anticoagulation therapy, with doses between 5 mg and 10 mg for the first 1 or 2 days for most individuals, with subsequent dosing based on the international normalized ratio (INR) response (Grade 1B); we suggest against pharmacogenetic-based dosing until randomized data indicate that it is beneficial (Grade 2C); and in elderly and other patient subgroups who are debilitated or malnourished, we recommend a starting dose of < or = 5 mg (Grade 1C). The article also includes several specific recommendations for the management of patients with nontherapeutic INRs, with INRs above the therapeutic range, and with bleeding whether the INR is therapeutic or elevated. For the use of vitamin K to reverse a mildly elevated INR, we recommend oral rather than subcutaneous administration (Grade 1A). For patients with life-threatening bleeding or intracranial hemorrhage, we recommend the use of prothrombin complex concentrates or recombinant factor VIIa to immediately reverse the INR (Grade 1C). For most patients who have a lupus inhibitor, we recommend a therapeutic target INR of 2.5 (range, 2.0 to 3.0) [Grade 1A]. We recommend that physicians who manage oral anticoagulation therapy do so in a systematic and coordinated fashion, incorporating patient education, systematic INR testing, tracking, follow-up, and good patient communication of results and dose adjustments [Grade 1B]. In patients who are suitably selected and trained, patient self-testing or patient self-management of dosing are effective alternative treatment models that result in improved quality of anticoagulation management, with greater time in the therapeutic range and fewer adverse events. Patient self-monitoring or self-management, however, is a choice made by patients and physicians that depends on many factors. We suggest that such therapeutic management be implemented where suitable (Grade 2B).

The international normalized ratio to prioritize patients for liver transplantation: problems and possible solutions

The prothrombin time (PT) test once designed by Dr Quick to investigate patients with obstructive jaundice was later adapted and standardized by means of the international normalized ratio (INR) to monitor patients on treatment with vitamin K antagonists (VKA). After more than 70 years from its introduction it is now time to think about its standardization for those very patients for whom it was intended at the beginning of its history. Two studies carried out independently and published recently in the same issue of a specialized journal do exploit the very same idea on how to accomplish this standardization. Both of them confirm previous anecdotal observations that the INR as devised for patients on VKA (INR(vka)) is not valid to harmonize PT results for patients with chronic liver disease. This fact, that at first sight may appear academic, has important consequences because the PT INR is used to construct the model for end-stage liver disease (MELD) scores, which is widely used to prioritize patients for liver transplantation. The two studies further demonstrate that an alternative calibration model, modified from that recommended by the World Health Organization for patients on VKA, may be feasible also for patients with chronic liver disease. This alternative calibration model, which calls for the substitution of plasmas from patients on VKA with those from patients with chronic liver disease, may be highly beneficial to harmonize the calculation of the MELD score, with important implications for the prioritization of patients for liver transplantation.

A modified international normalized ratio as an effective way of prothrombin time standardization in hepatology

International Normalized Ratio (INR), which standardizes prothrombin time (PT) during oral anticoagulation, has been extended to standardize PT in liver diseases and is included in prognostic models such as the Model for End stage Liver Disease (MELD). However, mechanisms of PT prolongation in liver diseases differ from those involved in oral anticoagulation, and the thromboplastin reagents differ in their sensitivities to these 2 mechanisms. Our aim was to determine whether, in the calibration model for thromboplastins proposed by the World Health Organization, the use of plasmas from patients with liver diseases instead of plasmas from patients on oral anticoagulation could lead to a new INR specific for liver diseases (INR "LD"), achieving a real standardization of PT. First, 5 thromboplastins were calibrated against an international reference using 60 plasmas of patients with liver failure and, in a second step, the variation of PT reported as seconds, the ratio of patient PT to normal PT, INR, and INR"LD" was assessed in 34 other patients. MELD scores were calculated with the INR values obtained with the 5 thromboplastins. Only INR"LD" eliminated variability in PT results observed with the different thromboplastins. The discrepancy between MELD scores were up to 4 and 7 points in 52% and 17% of the patients, respectively.

CONCLUSION

INR "LD" may provide a common international scale of PT reporting in hepatology. Its adoption would be an important step because of the significant impact on MELD score induced by interlaboratory variability in INR determination.

The international normalized ratio calibrated for cirrhosis (INR(liver)) normalizes prothrombin time results for model for end-stage liver disease calculation

The model for end-stage-liver-disease (MELD) is a mathematical score used to prioritize patients for liver transplantation and includes results for creatinine, bilirubin, and prothrombin time (PT) expressed as international normalized ratio (INR). The rationale of using the MELD rests on the assumption that the score would be the same across the country if the methods used to measure the variables yield the same numerical results regardless of the testing laboratory. Evidence was provided that specific methodologies may influence the MELD, and the PT-INR was identified as the most important. This study was designed to provide information on the between-thromboplastin variability and to explore alternatives to obviate such variability. Fifty-seven patients with cirrhosis were selected, and their PTs were measured with 7 thromboplastins. The thromboplastins were previously calibrated by testing plasmas from patients on vitamin K antagonists and healthy subjects to assign the international sensitivity index (ISI(vka)) needed to convert PT into INR. Each of the thromboplastins was also assigned an ISI(liver) by substituting in the calibration the plasmas from vitamin K antagonist patients with plasmas from patients with cirrhosis. INR and MELD values for individual patients were calculated by using the ISI(vka) or the ISI(liver). The mean INR(vka) obtained with the 7 thromboplastins were significantly different (P < 0.001). Conversely, the mean INR(liver) were not. Similarly, the mean MELD(vka) were significantly different (P < 0.001), but those differences were abrogated for the MELD(liver).

CONCLUSION

The alternative thromboplastin calibration using plasmas from patients with cirrhosis instead of from vitamin K antagonist patients is feasible and may resolve the variability of the MELD to prioritize patients for transplantation.