The Importance of International Normalized Ratio Monitoring in Patients With Mechanical Pulmonary Valve Prosthesis

Background

The most challenging risk of mechanical valves is thromboembolic events; therefore, life-long anticoagulation therapy is necessary. Anticoagulation therapy should be adjusted for each patient with serial international normalized ratio (INR) monitoring. Due to the small number of patients with a mechanical valve in the pulmonary position, we are facing a lack of information about the therapeutic range of the INR in these patients. We aimed to evaluate patients with a history of pulmonary valve replacement (PVR) who faced malfunction and compare their INR and echocardiographic data at the time of malfunction and 3 months prior.

Methods

In this cross-sectional study, 71 patients who had previously undergone PVR and presented to Shaheed Rajaie Cardiovascular Medical and Research Center with a diagnosis of pulmonary valve malfunction between 2014 and 2021 were included. Patients' INR and echocardiographic data at the time of the malfunction and 3 months before the malfunction diagnosis were gathered from the hospital's registry. IBM SPSS 20.0 was used for data analysis.

Results

In this cross-sectional study, 71 patients with mechanical pulmonary valve malfunction were included. 49.3% (n = 35) were men, 50.7% (n=36) were women, and their mean age was 33.23 (±8.279). The mean INR of all patients 3 months before malfunction and at the time of malfunction was 2.29 (±0.753) and 2.20 (±0.704), respectively.

Conclusion

In this study, most of our patients had an INR below the therapeutic range, both at the time of malfunction and 3 months prior. It emphasizes the importance of patient follow-up and keeping the INR in the therapeutic range.

The international normalised ratio to monitor coagulation factor production during normothermic machine perfusion of human donor livers

BACKGROUND

Normothermic machine perfusion (NMP) of donor livers allows for new diagnostic and therapeutic strategies. As the liver produces most of the haemostatic proteins, coagulation assays such as the International Normalised Ratio (INR) performed in perfusate may be useful to assess hepatocellular function of donor livers undergoing NMP. However, high concentrations of heparin and low levels of fibrinogen may affect coagulation assays.

METHODS

Thirty donor livers that underwent NMP were retrospectively included in this study, of which 18 were subsequently transplanted. We measured INRs in perfusate in presence or absence of exogenously added fibrinogen and/or polybrene. Additionally, we prospectively included 14 donor livers that underwent NMP (of which 11 were transplanted) and measured INR using both a laboratory coagulation analyser and a point-of-care device.

RESULTS

In untreated perfusate samples, the INR was above the detection limit in all donor livers. Addition of both fibrinogen and polybrene was required for adequate INR assessment. INRs decreased over time and detectable perfusate INR values were found in 17/18 donor livers at the end of NMP. INR results were similar between the coagulation analyser and the point-of-care device, but did not correlate with established hepatocellular viability criteria.

CONCLUSIONS

Most of the donor livers that were transplanted showed a detectable perfusate INR at the end of NMP, but samples require processing to allow for INR measurements using laboratory coagulation analysers. Point-of-care devices bypass this need for processing. The INR does not correlate with established viability criteria and might therefore have additional predictive value.

Delta neutrophil index as a prognostic factor for mortality in patients with Fournier's gangrene

OBJECTIVES

The delta neutrophil index represents the fraction of circulating immature granulocytes and is a marker of infection and sepsis. Our study aimed to evaluate the usefulness of the delta neutrophil index in predicting mortality in patients with Fournier's gangrene.

METHODS

We enrolled patients with Fournier's gangrene who were admitted to the Wonju Severance Christian Hospital (Wonju, Korea) between September 2010 and December 2021. We retrospectively analyzed the patients' characteristics, factors related to management, scoring systems such as the Fournier's Gangrene Severity Index, and laboratory data measured at initial presentation.

RESULTS

There were 58 (68.2%) survivors and 27 (31.8%) non-survivors. The initial levels of serum lactate, hemoglobin, delta neutrophil index, albumin, international normalized ratio, creatinine, Fournier's Gangrene Severity Index, Uludag Fournier's Gangrene Severity Index, and prognostic nutritional index differed between survivors and non-survivors. Age, international normalized ratio, and delta neutrophil index were independent predictors of mortality in Fournier's gangrene. In receiver operating characteristic curve analysis, delta neutrophil index on the day of admission was the best indicator of mortality (area under the curve, 0.804; 95% confidence interval [0.679-0.929]). The optimal cutoff for delta neutrophil index in predicting mortality was 11.25% (sensitivity, 74.1%; specificity, 91.4%). The initial delta neutrophil index was the best indicator of mortality (area under the curve, 0.804; 95% confidence interval 0.679-0.929).

CONCLUSION

The delta neutrophil index can be useful for predicting mortality in patients with Fournier's gangrene. A delta neutrophil index >11.25% at initial presentation is a reliable predictor of Fournier's gangrene.

[Comparative study in primary care of the stability of INR in patients treated with warfarin or fluindione for atrial fibrillation. The FLOWER study (FLuindione Or WarfarinE - Result INR)]

INTRODUCTION

The aim of our study was to compare the time spent within the target INR or Time in Therapeutic Range (TTR) of patients treated with fluindione to that of patients treated with warfarin for non-valvular atrial fibrillation (NVAF) and followed in general practice, with the hypothesis of a better TTR with warfarin, which is the VKA most commonly prescribed in France.

METHOD

Liberal nurses and general practitioners working in the Auvergne region recruited patients treated with fluindione or warfarin for NVAF. Patients' INRs (International Normalized Ratios) were recorded by medical analysis laboratories for 6 months. The primary endpoint was TTR, the secondary endpoint the number of hemorrhagic and/or thromboembolic events.

RESULTS

Of the 342 participants with a mean age of 75.3 ± 9.8 years, 239 (70%) were treated with fluindione and 103 (30%) with warfarin. The mean number of INRs achieved per patient was 9.2 ± 4.0 in the fluindione group and 9.3 ± 4.0 in the warfarin group (p=0.73). The median TTR of fluindione was 81.9% [63.5; 94.1] and that of warfarin was 81.3% [65.6; 92.6] (p=0.98). Twenty-eight of 263 patients reported hemorrhage (10.6%) and 4 reported thromboembolic events (0.8%), with no significant difference between the groups.

CONCLUSION

The TTRs of patients treated for NVAF with fluindione versus warfarin do not differ significantly over an observation period of 6 consecutive months in a patient population comparable to that of the publications in this field. However, these TTRs are significantly higher than those reported in the literature, with no difference between the two treatments. The TTRs of patients treated for VANF with fluindione versus warfarin do not differ significantly over a 6-month observation period in a patient population comparable to that of the publications in this indication.

Analysis of the quality of anticoagulation with vitamin K antagonists in three clinical scenarios in Mexico

INTRODUCTION

Vitamin K antagonists (VKA) are a therapeutic alternative in patients with venous thromboembolic disease; however, numerous factors affect their pharmacology.

OBJECTIVE

To evaluate the quality of VKA anticoagulation at three different time periods in Mexico.

METHODS

Prospective study, nested in patient cohorts at three different clinical scenarios between 2013 and 2019. Outpatients with indication for treatment with VKAs for at least 12 months were included. Patients were managed according to the criteria of the treating physician.

RESULTS

Patient general characteristics were similar between groups, except for the VKA indication. The results of 4,148 patients and 38,548 INR assessments were analyzed. The times in therapeutic range during the three phases of the study and pooled data were significantly higher for the anticoagulation clinic. Only the number of patient visits was significantly associated with the results, unlike age, gender, and type of VKA.

CONCLUSIONS

VKAs are widely used, but it is difficult for therapeutic goals to be achieved, especially in non-specialized clinical services. Creation of anticoagulation clinics is an urgent need for the Mexican health system.

Bias and uncertainty of the International Normalized Ratio determined with a whole blood point-of-care prothrombin time test device by comparison to a new International Standard for thromboplastin

BACKGROUND

Whole blood point-of-care PT/INR test devices, e.g. CoaguChek XS, are calibrated by their manufacturers. In the Netherlands, each new lot of test strips for CoaguChek XS is validated by a group of anticoagulant clinics collaborating with a Coagulation Reference Laboratory. In 2017, a new International Standard for recombinant human thromboplastin (coded rTF/16) has been established by the World Health Organization.

AIM

To assess uncertainty of the validation procedure and the magnitude of the INR bias of a series of consecutive lots of test strips imported in the Netherlands.

METHODS

CoaguChek XS test strip INR results were compared to INRs determined with the new International Standard rTF/16. Comparisons were made with variable numbers of blood samples obtained from patients treated with vitamin K-antagonists. Relationships between CoaguChek XS and rTF/16 results were determined with orthogonal regression analysis. The relationships were used to assess bias and uncertainty of bias.

RESULTS

Average bias between CoaguChek XS test results and rTF/16 depends on the INR level. Overall, there was a trend of increasing bias and increasing uncertainty with increasing INR values. Along the sequence of 47 consecutive lots, a temporary fluctuation of bias was observed. At an INR level of 3.0 the average bias was less than 10% in all cases, but at an INR of 4.0 there were 5 lots with average bias between 10 and 15%.

CONCLUSION

Validation of test strips is useful to assess bias but depends on availability of fresh patients' samples and traceability to an accepted Reference Measurement System.

An illustrated review of bleeding assessment tools and common coagulation tests

Recognizing the complexity of coagulation tests and currently used anticoagulants, we developed this illustrated review on bleeding assessment tools and common coagulation screening tests. Quantitative bleeding assessment tools (BATs) are available to standardize the bleeding history and improve the pretest probability prior to coagulation testing. We describe use of BATs and the principles, indications, and limitations of the prothrombin time (PT)/International Normalized Ratio, activated partial thromboplastin time (APTT), and 50:50 mix. Use of these tests to identify coagulation factor deficiencies, specific and nonspecific inhibitors, coagulopathy of liver disease, disseminated intravascular coagulation, and commonly used anticoagulant medications are reviewed. Current literature suggests that unnecessary coagulation testing is rampant. The PT and APTT have astoundingly low sensitivity (1.0%-2.1%) for detection of clinically significant bleeding disorders. Thus, current guidelines recommend against the use of screening PT and APTT in preoperative patients undergoing noncardiac/vascular surgery.

Quality of anticoagulant therapy and the incidence of in-stent thrombosis after venous stenting

BACKGROUND

In patients with a venous outflow obstruction following iliofemoral deep vein thrombosis stenting of the venous tract to prevent or alleviate postthrombotic syndrome is applied with increasing frequency. The impact of the quality of anticoagulant therapy with vitamin K antagonists (VKAs) on the development of in-stent thrombosis is currently unknown.

OBJECTIVES

To determine the association between the quality of postinterventional VKA treatment and the occurrence of in-stent thrombosis.

METHODS

Seventy-nine patients with iliofemoral and/or caval venous stent placement for obstruction of the venous outflow were included in this study. All patients received postinterventional VKA. The quality of VKA anticoagulant therapy was expressed as the time within therapeutic range (TTR) calculated using the linear interpolation method and as the proportion of International Normalized Ratio (INR) values < 2.0. In-stent thrombosis was assessed by the use of duplex ultrasound. Survival analysis (Kaplan-Meier curves, Cox regression) was used to analyze the data.

RESULTS

In-stent thrombosis developed in 16 patients (20.3%). The total population had a mean TTR of 64.0% (±19.0) and a mean proportion of INR values < 2.0 of 11.6% (±12.0). Overall, a TTR < 49.9% was associated with an increased risk of in-stent thrombosis. The multivariable adjusted analysis showed a hazard ratio (HR) of 0.96 (95% confidence interval [CI], 0.92-0.99; P = .02) per 1% increase in TTR. The proportion of INR values < 2.0 had no significant association with the occurrence of in-stent thrombosis: HR 0.98 (95% CI, 0.91-1.06; P = .66).

CONCLUSIONS

We conclude that the quality of anticoagulant treatment reflected in the TTR following a venous stenting procedure is an important independent determinant for the risk of in-stent thrombosis. The role of anticoagulant treatment for the prevention of in-stent thrombosis following stenting procedures therefore merits further research.

Impact of an extended International Normalized Ratio follow-up interval on healthcare use among veteran patients on stable warfarin doses

PURPOSE

To analyze the impact of a 12-week extended International Normalized Ratio (INR) follow-up interval on healthcare use.

METHODS

A prospective cohort study of the use of an extended INR follow-up interval of up to 12 weeks was conducted over 2 years in a pharmacist-managed anticoagulation clinic. A detailed protocol was used to extend the INR follow-up interval to 5-6 weeks and then 7-8 weeks and 11-12 weeks. The number of planned and unplanned anticoagulation encounters, procedures requiring warfarin interruption, telephone triage phone calls, emergency department visits, and hospitalizations were collected. A post hoc subanalysis was also completed on participants who were scheduled for 4 consecutive 12-week intervals.

RESULTS

Compared to baseline, at 12 months there was a mean decrease in planned anticoagulation encounters of 2.24 visits (p < 0.001) among 44 participants. From 12 to 24 months compared to baseline, there was a mean decrease in planned anticoagulation encounters of 3.13 visits (p < 0.001) and an increase of 0.54 unplanned anticoagulation encounters (p = 0.04) among 39 participants. The remainder of healthcare use variables were not statistically significantly different from baseline at any time point. Of the 15 participants scheduled for 4 consecutive 12-week intervals, there was a decrease from baseline of approximately 5 visits over the course of a year (p < 0.001).

CONCLUSION

An extended INR follow-up interval appears to decrease anticoagulation healthcare use without an increase in acute healthcare use. While this intervention could be cost-effective, institutions need to consider safety, efficacy, and feasibility prior to implementation.

[Possibility of using coagulation factor Ⅱ and factor Ⅹ for warfarin monitoring in Chinese pulmonary embolism patients]

Objective: To explore the possibility of using coagulation factor Ⅱ and Ⅹ (FⅡ and FⅩ) for warfarin monitoring among Chinese pulmonary embolism patients. Methods: Blood samples were collected from pulmonary embolism patients who were taking warfarin as anticoagulant and who were from Peking Union Medical Collaege Hospital during Mar 2016 and Oct 2018. Activity of coagulation factor Ⅱ/Ⅹ and International Normalized Ratio (INR) level were detected. Correction analysis was used to investigate the relationship between activity of coagulation factor Ⅱ/Ⅹ and INR. Receiver Operating Characteristic (ROC) curve was used to analyze the diagnostic ability of FⅡ and FⅩ. Results: A total of 157 blood samples were collected in this research. When 1.5≤INR≤3.0, FⅡ (r=-0.768, P<0.001) and FⅩ(r=-0.690, P<0.001) were in inverse correlations with INR. Area under ROC curve (AUC) for FⅡ and FⅩ was 0.961 and 0.965 (P<0.001) when we used INR<2.0 as the criteria of anticoagulant inadequacy. AUC of ROC for FⅡ and FⅩ was 0.885 and 0.890 (P<0.001) when we used INR≤3.0 as the criteria of not over-anticoagulation. Conclusion: FⅡ and FⅩ activity can be used as the therapeutic markers of warfarin in Chinese pulmonary embolism patients.

[Bridging anticoagulation in patients receiving vitamin K antagonists : Current status]

Approximately 30% of patients receiving oral anticoagulation using vitamin K antagonists (VKA) require surgery within 2 years. In this context, a clinical decision on the need and the mode of a peri-interventional bridging with heparin is needed. While a few years ago, bridging was almost considered a standard of care, recent study results triggered a discussion on which patients will need bridging at all. Revisiting the currently available recommendations and study results the conclusion can be drawn that the indications for bridging with heparin must nowadays be taken more narrowly and considering the individual patient risk of bleeding and thromboembolism. Bridging with heparin is only needed in patients with a very high risk of thromboembolism. This overview aims to give guidance for a risk-adapted peri-interventional approach to management of patients with a need for long-term anticoagulation using VKA.

Improving warfarin therapy through implementation of a hospital-based pharmacist managed clinic in Jamaica

Background

Pharmacist managed warfarin clinics can improve the anticoagulation status of non-valvular patients. The first of such services was implemented at the Cornwall Regional Hospital in Jamaica in 2013.

Objectives

To assess the anticoagulation control of patients on warfarin therapy over six months in the pharmacist managed warfarin clinic at Cornwall Regional Hospital.

Methods

Retrospective docket review for the period January 2014 to December 2016 was done to include data of patients attending routine clinic appointments for at least six months. Age, gender, date of visit, indication for warfarin therapy, warfarin dose and International Normalized Ratio readings were extracted. Percentage time spent in therapeutic range (TTR) was calculated by month for six months using the Rosendaal linear interpolation method. Patient anticoagulation status was categorized as poor (TTR<40%), moderate (TTR=40-64%) or good (TTR≥65%) and anticoagulation status at three months and six months was compared.

Results

For the period of assessment, 52 patients were identified; the median age was 58 years and 36 patients were males. Deep vein thrombosis was the main indication for therapy (22 of 52) and median warfarin weekly dose ranged was 15.0-130 mg. At time of recruitment most of the patients were outside the target INR range (43 of 52). Within one month, the median TTR attained was 31% [IQR 62-10]. This significantly improved by second month to 60% [IQR 82-23] (p=0.001). By month three, the proportion of patients in good, moderate and poor anticoagulant status was 19/51, 15/51 and 17/51 respectively, which at six months changed to 23/51, 12/51. 16/51 respectively; thus, although coagulation status improved from month one to three, there was no significant improvement from month three to month six (p=0.31).

Conclusions

The pharmacist managed warfarin clinic monitoring services were successful in attaining TTRs >40% and sustaining these values over six months. The services should therefore be encouraged.

[Bridging anticoagulation in patients receiving vitamin K antagonists : Current status]

Approximately 30% of patients receiving oral anticoagulation using vitamin K antagonists (VKA) require surgery within 2 years. In this context, a clinical decision on the need and the mode of a peri-interventional bridging with heparin is needed. While a few years ago, bridging was almost considered a standard of care, recent study results triggered a discussion on which patients will need bridging at all. Revisiting the currently available recommendations and study results the conclusion can be drawn that the indications for bridging with heparin must nowadays be taken more narrowly and considering the individual patient risk of bleeding and thromboembolism. Bridging with heparin is only needed in patients with a very high risk of thromboembolism. This overview aims to give guidance for a risk-adapted peri-interventional approach to management of patients with a need for long-term anticoagulation using VKA.

User Evaluation of a Smartphone Application for Anticoagulation Therapy

Anticoagulation therapy with Warfarin is used for specific cardiovascular diseases to control the ability of blood clotting. Traditional ways of self-management therapy are based on paper forms and procedures. This paper presents an evaluation of the smartphone application Warfarin Guide, a computer-assisted decision-support system used to help patients in their management of anticoagulation therapy related to International Normalized Ratio (INR) values. The evaluation consisted of a usability test with 4 participants and a field test with 14 participants who used the application at home during four months. A mixed methods research approach included quantitative and qualitative analysis of the test results. The results showed that participants evaluated the Warfarin Guide as 'useful' for self-management of anticoagulation therapy, reporting key issues for further improvement.

International collaborative study for the calibration of proposed International Standards for thromboplastin, rabbit, plain, and for thromboplastin, recombinant, human, plain

Essentials Two candidate International Standards for thromboplastin (coded RBT/16 and rTF/16) are proposed. International Sensitivity Index (ISI) of proposed standards was assessed in a 20-centre study. The mean ISI for RBT/16 was 1.21 with a between-centre coefficient of variation of 4.6%. The mean ISI for rTF/16 was 1.11 with a between-centre coefficient of variation of 5.7%.

SUMMARY

Background The availability of International Standards for thromboplastin is essential for the calibration of routine reagents and hence the calculation of the International Normalized Ratio (INR). Stocks of the current Fourth International Standards are running low. Candidate replacement materials have been prepared. This article describes the calibration of the proposed Fifth International Standards for thromboplastin, rabbit, plain (coded RBT/16) and for thromboplastin, recombinant, human, plain (coded rTF/16). Methods An international collaborative study was carried out for the assignment of International Sensitivity Indexes (ISIs) to the candidate materials, according to the World Health Organization (WHO) guidelines for thromboplastins and plasma used to control oral anticoagulant therapy with vitamin K antagonists. Results Results were obtained from 20 laboratories. In several cases, deviations from the ISI calibration model were observed, but the average INR deviation attributabled to the model was not greater than 10%. Only valid ISI assessments were used to calculate the mean ISI for each candidate. The mean ISI for RBT/16 was 1.21 (between-laboratory coefficient of variation [CV]: 4.6%), and the mean ISI for rTF/16 was 1.11 (between-laboratory CV: 5.7%). Conclusions The between-laboratory variation of the ISI for candidate material RBT/16 was similar to that of the Fourth International Standard (RBT/05), and the between-laboratory variation of the ISI for candidate material rTF/16 was slightly higher than that of the Fourth International Standard (rTF/09). The candidate materials have been accepted by WHO as the Fifth International Standards for thromboplastin, rabbit plain, and thromboplastin, recombinant, human, plain.

Laboratory characteristics of ischemic stroke patients with atrial fibrillation on or off therapeutic warfarin

BACKGROUND

In patients with atrial fibrillation (AF), despite adequate anticoagulation, ischemic stroke (IS) is an uncommon yet concerning occurrence.

HYPOTHESIS

Specific laboratory parameters may affect the efficacy of warfarin despite therapeutic international normalized ratio (INR) in patient with AF who present with IS.

METHODS

We used the database from a multicenter clinical trial to identify AF patients who presented with IS. We trichotomized the cohort into patients with therapeutic INR on warfarin, subtherapeutic INR on warfarin, and on no anticoagulants. We then compared baseline laboratory characteristics and other baseline features among the groups.

RESULTS

Patients with therapeutic INR presented with higher serum creatinine (P = 0.01) and blood urea nitrogen (P = 0.02) and lower glomerular filtration rates (P = 0.001) compared with other groups. Other laboratory parameters were not different among the 3 groups. Patients with therapeutic INR also presented with milder stroke symptoms (P = 0.01). Medical history of the 3 groups was not different, except for history of valvular heart disease, which was more prevalent in patients with therapeutic INR (P = 0.004). In-hospital mortality rates and 90-day disability were not different among the 3 groups.

CONCLUSIONS

AF patients who presented with IS on therapeutic warfarin had higher average serum creatinine and blood urea nitrogen, and lower glomerular filtration rates, compared with others. Impaired renal function may be a factor contributing to occurrence of IS in AF patients despite adequate anticoagulation. Larger, targeted studies are needed to confirm these findings.

Notification of international normalized ratio test in atrial fibrillation patients treated with warfarin via short message service: Study protocol for a randomized controlled trial

BACKGROUND

Atrial Fibrillation (AF) is the most common abnormal heart rhythm. AF patients usually use warfarin therapy. Safety and efficacy of warfarin are dependent on maintaining the International Normalized Ratio (INR) within the therapeutic range.

OBJECTIVE

We will use a Short Message Service (SMS) to evaluate the effect of a reminder on carrying out the INR laboratory test in a timely manner.

METHODS

This study (a Randomized Controlled Trial) will be done in Loghman hospital Tehran, Iran. Convenience sampling will be done and 400 AF patients that have inclusion criteria will be randomized equally to an intervention or control group. Patients in the intervention group will receive an SMS that will remind them of the INR test date. The SMS will be sent at 6 PM on the day before and 8 AM on the scheduled date but the patients of the control group will receive usual care without any SMS reminders. We will evaluate the effect of reminders on carrying out the INR test in a timely manner and maintaining the INR in the therapeutic range. Patients' follow-up will be done via telephone conversation to identify thromboembolic events, bleeding and mortality. The data will be analyzed by IBM SPSS version 24. We will use independent samples t-test or Mann-Whitney and Chi-square tests for the analyses of outcomes.

DISCUSSION

This protocol describes the randomized control trial to study the effects of the SMS reminder system on adherence to the timing of INR test in AF patients treated with warfarin. The research will also form the basis for future decision support systems for monitoring of patients who receive oral anticoagulants.

TRIAL REGISTRATION

Iranian Registry of Clinical Trials (http://www.irct.ir) was used to register the trial and IRCT ID was IRCT2016052528070N1.

FUNDING

This research was supported by Mashhad University of Medical Sciences.

Monitoring of treatment with vitamin K antagonists: recombinant thromboplastins are more sensitive to factor VII than tissue-extract thromboplastins

Essentials Differences in sensitivity to factor VII (FVII) have been suggested between thromboplastins. FVII-induced International Normalized Ratio (INR) changes differ between commercial reagents. Recombinant human thromboplastins are more sensitive to FVII than tissue-extract thromboplastins. Thromboplastin choice may affect FVII-mediated INR stability.

SUMMARY

Background Differences regarding sensitivity to factor VII have been suggested for recombinant human and tissue-extract thromboplastins used for International Normalized Ratio (INR) measurement, but the evidence is scarce. Differences in FVII sensitivity are clinically relevant, as they can affect INR stability during treatment with vitamin K antagonists (VKAs). Objectives To determine whether commercial thromboplastins react differently to changes in FVII. Methods We studied the effect of addition of FVII on the INR in plasma by using three tissue-extract (Neoplastin C1+, Hepato Quick, and Thromborel S) and three recombinant human (Recombiplastin 2G, Innovin, and CoaguChek XS) thromboplastins. Three different concentrations of purified human FVII (0.006, 0.012 and 0.062 μg mL-1 plasma), or buffer, were added to five certified pooled plasmas of patients using VKAs (INR of 1.5-3.5). Changes in FVII activity were measured with two bioassays (Neoplastin and Recombiplastin), and relative INR changes were compared between reagents. Results After addition of 0.062 μg mL-1 FVII, FVII activity in the pooled plasmas increased by approximately 20% (Neoplastin) or 32% (Recombiplastin) relative to the activity in pooled normal plasma. All thromboplastins showed dose-dependent INR decreases. The relative INR change in the pooled plasmas significantly differed between the six thromboplastins. No differences were observed among recombinant or tissue-extract thromboplastins. Pooled results indicated that the FVII-induced INR change was greater for recombinant than for tissue-extract thromboplastins. Conclusions Differences regarding FVII sensitivity exist between various thromboplastins used for VKA monitoring. Recombinant human thromboplastins are more sensitive to FVII than tissue-extract thromboplastins. Therefore, thromboplastin choice may affect FVII-mediated INR stability.

Warfarin Guide: Co-Design of a Mobile Computer-Assisted Anticoagulant Therapy

Patients with some types of cardiovascular disease are prescribed anticoagulation therapy with Warfarin in order to control the ability of blood clotting. This work presents a co-designed mobile application, called Warfarin Guide, for a computer-assisted anticoagulant therapy. The application addresses the challenges that unexperienced patients may find when having to remember to regularly check their INR values and make temporary adjustments for INR value fluctuations that are not easy to interpret without direct medical advice.

Correction factor to improve agreement between point-of-care and laboratory International Normalized Ratio values

PURPOSE

Results of a research project to quantify and improve the accuracy of point-of-care (POC) International Normalized Ratio (INR) values are reported.

METHODS

The accuracy of POC INR values relative to laboratory-measured INR values was retrospectively assessed in a cohort of patients with same-day INR determinations by both methods. Univariate linear regression was performed to derive a correction factor for POC INR values of >3; this correction factor was validated in a second cohort.

RESULTS

In the derivation cohort (259 patients and 344 paired INR results), agreement of POC values with corresponding laboratory INR values at two specified thresholds (±15% and ±25%) was 51.2% and 66.6%, respectively; for POC INR values of >3 (n = 205), agreement was lower (24.9% and 44.9%, respectively). Univariate linear regression yielded a coefficient of 0.77 (95% confidence interval, 0.76-0.79; p < 0.001). Applying a correction factor of 0.8 to POC INR values in a validation cohort (169 patients and 209 paired INR values) significantly improved the accuracy of POC INR values of >3 relative to laboratory values (from 7% to 71.1% at the lower threshold and from 23.5% to 88.8% at the higher threshold, p < 0.0001 for both comparisons).

CONCLUSION

Agreement between POC and laboratory INR results in one institution was poor, especially when POC INR values exceeded 3. Application of an institution-specific correction factor to POC INR values of >3 improved agreement with laboratory INR results but would not have significantly reduced differences in protocol-based warfarin dosage adjustments.

Evaluation of Time in Therapeutic Range (TTR) in Patients with Non-Valvular Atrial Fibrillation Receiving Treatment with Warfarin in Tehran, Iran: A Cross-Sectional Study

INTRODUCTION

Anticoagulant control is assessed by Time in Therapeutic Range (TTR). For a given patient, TTR is defined as the duration of time in which the patient's International Normalized Ratio (INR) values were within a desired range.

AIM

To assess TTR in patients receiving treatment with warfarin for non-valvular atrial fibrillation at a referral center for cardiovascular diseases in Tehran, Iran.

MATERIALS AND METHOD

Over 6 months, we enrolled eligible patients presenting to Shaheed Rajaie Hospital in Tehran for regular INR testing. Demographic data, medical history, and current medications were determined for all participants. TTR was assessed by the Rosendaal method.

RESULTS

A total of 470 patients (mean age 58.0±14.2 years, 60.2% women) underwent 1450 INR measurements. The mean TTR was calculated as 54.9±11.9%. Of the sample patients, 37.3% were in the good control category (TTR > 70%), 24.6% were in the intermediate category (50% < TTR < 70%), and 38.1% were in the poor control category (TTR < 50%). The number of current medications above four was a significant predictor of poor control (OR = 2.06; 95% CI, 1.87, 2.23). The mean TTR of the studied patients (54.9%) was below the good control range.

CONCLUSION

The quality of anticoagulant therapy with warfarin in Iranian patients was poorer than that reported in European countries. Based on these results, research considering the causes of poor TTR among Iranian patients is recommended.

Predictors of anticoagulation quality in 15 834 patients performing patient self-management of oral anticoagulation with vitamin K antagonists in real-life practice: a survey of the International Self-Monitoring Association of Orally Anticoagulated Patients

Although patient self-management (PSM) of oral anticoagulation with vitamin K antagonists is recommended for patients requiring long-term anticoagulation, important aspects are still unclear. Using data from a large international survey (n = 15 834; median age 72 years; 30·1% female), we studied predictors of poor anticoagulation control (percentage of International Normalized Ratio values within therapeutic range below 75%) and developed a simple prediction model. The following variables were identified as risk factors for poor anticoagulation control and included in the final model: higher intensity of therapeutic range (odds ratio [OR] on every level 1·9; 95% confidence interval [CI] 1·8-2·0), long intervals between measurements (>14 d; 1·5; 95% CI 1·3-1·7), female sex (OR 1·3; 95% CI 1·2-1·4), and management other than PSM (OR 1·4; 95% CI 1·2-1·6). At a threshold of 0·2 (at least one variable present), the model predicted poor anticoagulation control with a sensitivity of 85·3% (95% CI: 84·0, 86·4) and a specificity of 28·5% (27·6, 29·5). The area under the receiver operated characteristic curve was 0·65. Using the proposed prediction model, physicians will be able to identify patients with a low chance of performing well, considering additional training, regular follow-up, or adjustment of therapeutic ranges.

The effect of carbamazepine on warfarin anticoagulation: a register-based nationwide cohort study involving the Swedish population

BACKGROUND

There are data indicating that the interaction between warfarin and carbamazepine results in decreased warfarin efficacy. However, the evidence on the magnitude of and interindividual differences in susceptibility to this interaction has remained scarce.

OBJECTIVES

To investigate the effect of carbamazepine on warfarin anticoagulation and warfarin maintenance doses by the use of data from three nationwide registries.

PATIENTS/METHODS

In a retrospective cohort study including 166 patients, warfarin doses were compared 2-4 weeks before and 10-13 weeks after initiation of cotreatment with carbamazepine. In addition, warfarin doses and International Normalized Ratio (INR) values were calculated week-by-week during cotreatment. Data on prescribed warfarin doses and INR measurements were obtained from two large Swedish warfarin registers. Data on carbamazepine use were retrieved from the Swedish Prescribed Drug Register.

RESULTS

The average warfarin doses were 49% (95% confidence interval 43-56) higher during carbamazepine treatment. The INR decreased upon carbamazepine initiation, and subtherapeutic INR levels were observed in 79% of all patients during the fifth week of cotreatment. Warfarin maintenance dose increases exceeding 50% and 100% were observed in 59% and 17% of patients, respectively.

CONCLUSIONS

Four of five warfarin-treated patients in whom cotreatment with carbamazepine was initiated experienced subtherapeutic anticoagulative effect within 3-5 weeks. The warfarin dose was subsequently increased by 49%, a change that differed widely between patients. In order to avoid thrombosis and ischemic stroke, carbamazepine initiation should be accompanied by close INR monitoring to better meet the anticipated increase in dose demand.

Anticoagulation-related nephropathy

Anticoagulation-related nephropathy (ARN) is a significant but underdiagnosed complication of anticoagulation that is associated with increased renal morbidity and all-cause mortality. Originally described in patients receiving supratherapeutic doses of warfarin who had a distinct pattern of glomerular hemorrhage on kidney biopsy, ARN is currently defined as acute kidney injury (AKI) without obvious etiology in the setting of an International Normalized Ratio (INR) of > 3.0. The underlying molecular mechanism is thought to be warfarin-induced thrombin depletion; however, newer studies have hinted at an alternative mechanism involving reductions in activated protein C and endothelial protein C receptor signaling. Prompt recognition of ARN is critical, as it is associated with accelerated progression of chronic kidney disease, and significant increases in short-term and long-term all-cause mortality. Prior investigations into ARN have almost universally focused on anticoagulation with warfarin; however, recent case reports and animal studies suggest that it can also occur in patients taking novel oral anticoagulants. Differences in the incidence and severity of ARN between patients taking warfarin and those taking novel oral anticoagulants are unknown; a post hoc analysis of routinely reported adverse renal outcomes in clinical trials comparing warfarin and novel oral anticoagulants found no significant difference in the rates of AKI, a prerequisite for ARN. Given the significant impact of ARN on renal function and all-cause mortality, a thorough understanding of the pathophysiology, molecular mechanisms, clinical spectrum and therapeutic interventions for ARN is crucial to balance the risks and benefits of anticoagulation and optimize treatment.

Drug-related problems and potential contributing factors in the management of deep vein thrombosis

Background

Patients receiving anticoagulant drugs must be carefully screened for drug-related problems, as such medications, including warfarin have narrow therapeutic ranges and a high potential for complications. Thus, this study was designed to assess drug-related problems in the management of patients with deep vein thrombosis at Tikur Anbessa Specialized Hospital.

Methods

A cross-sectional descriptive study involving retrospective chart review of adult patients with deep vein thrombosis was conducted from patients who visited the hospital from July 2012 to June 2013, using structured data collection format and this was complemented by key informant interview.

Results

The study included 91 patients with venous thromboembolism. Fifty three (58.2 %) were females. Mean age was 38.6 (±13.76) years and more than 2/3 were below the age of 44 years. About 54 % of them presented with concurrent medical conditions and most commonly with cancer. Adjustment of warfarin dose up or down was done in increments of 16 to 100 % for recent subtherapeutic International Normalized Ratios, 16 to 50 % for therapeutic and 11 to 66 % for overtherapeutic International Normalized Ratios, with the mean of 36.5 (±18.03) based on the cumulative weekly dose of warfarin. There was significant linear relationship between percentage of dose change and consequent International Normalized Ratio values (R² = 0.419; p = 0.000). Accordingly, more than 51 % of them presented with nontherapeutic International Normalized Ratio ranges following dose adjustment.

Conclusions

The most prevalent anticoagulation drug-related problems were subtherapeutic doses, overtherapeutic doses and potential drug interactions. Institutional validated decision support tools for dosing decisions during maintenance anticoagulation therapy should be developed and used accordingly in order to prevent recurrent and hemorrhagic complications and to improve clinical outcomes.

Point-of-care testing and INR within-subject variation in patients receiving a constant dose of vitamin K antagonist

Many patients treated with vitamin K antagonists (VKA) determine their INR using point-of-care (POC) whole blood coagulation monitors. The primary aim of the present study was to assess the INR within-subject variation in self-testing patients receiving a constant dose of VKA. The second aim of the study was to derive INR imprecision goals for whole blood coagulation monitors. Analytical performance goals for INR measurement can be derived from the average biological within-subject variation. Fifty-six Thrombosis Centres in the Netherlands were invited to select self-testing patients who were receiving a constant dose of either acenocoumarol or phenprocoumon for at least six consecutive INR measurements. In each patient, the coefficient of variation (CV) of INRs was calculated. One Thrombosis Centre selected regular patients being monitored with a POC device by professional staff. Sixteen Dutch Thrombosis Centres provided results for 322 selected patients, all using the CoaguChek XS. The median within-subject CV in patients receiving acenocoumarol (10.2 %) was significantly higher than the median CV in patients receiving phenprocoumon (8.6 %) (p = 0.001). The median CV in low-target intensity acenocoumarol self-testing patients (10.4 %) was similar to the median CV in regular patients monitored by professional staff (10.2 %). Desirable INR analytical imprecision goals for POC monitoring with CoaguChek XS in patients receiving either low-target intensity acenocoumarol or phenprocoumon were 5.1 % and 4.3 %, respectively. The approximate average value for the imprecision of the CoaguChek XS, i. e. 4 %, is in agreement with these goals.

Macroscopic hematuria in patients on anticoagulation therapy

INTRODUCTION

Visible hematuria is not rare in patients on anticoagulant therapy. There is no consensus regarding the diagnostic approach for them; some authors suggest restricted volume of diagnostic procedures because of the low number of urological etiology found. Some antibiotics have been reported to potentiate the effect of oral anticoagulants.

MATERIAL AND METHODS

The study addresses the need for urological assessment of patients on anticoagulation therapy and the possible role of some drugs administrated simultaneously with an oral anticoagulant, for the onset of macroscopic hematuria. Patients hospitalized with hematuria, both with or without anticoagulation therapy, were investigated and followed up.

RESULTS

The onset of hematuria depends on the monitoring of oral anticoagulation. INR (International Normalized Ratio) value corresponds with the probability of non-urological etiology, where INR>4 carries relatively low risk for urological and malignant etiology. Some antibiotics may influence the anticoagulation effect, so INR value may be elevated and hematuria may occur.

CONCLUSIONS

Anticoagulation therapy should be administrated carefully and individually. The risk of urological etiology of hematuria is lower in patients on oral anticoagulants (especially when INR >4), however, it is not zero.

Agreement between Coaguchek XS and STA-R Evolution (Hepato Quick) INR results depends on the level of INR

INTRODUCTION

Introducing point-of-care (POC) INR measurement to monitor anticoagulant therapy may be beneficial for both patients and anticoagulation clinics. However, agreement between POC and laboratory INR results is still unclear, especially at sub- and supratherapeutic levels. Therefore we investigated the analytical and clinical agreement between POC INR results of the Coaguchek XS and laboratory INR results of the STA-R Evolution.

MATERIALS AND METHODS

Paired POC and laboratory INR results were obtained and analyzed in 3257 patients aged 18-104 years between August 2008 and March 2014.

RESULTS

Mean difference between POC and laboratory results ranged from -0.18 (95%CI -0.20;-0.16) INR point for POC results 2.0-3.0, up to 1.14 (95%CI 0.87;1.42) INR point for POC results 7.1-8.0. In the therapeutic range (POC INR 2.0-4.0), mean difference between POC and laboratory results was -0.13 (95%CI -0.15;-0.12) INR point. At subtherapeutic (POC INR <2.0) and supratherapeutic (POC INR >4.0) INR levels, mean differences were -0.13 (95%CI -0.15;-0.11) and 0.72 (95%CI 0.63;0.80) INR point, respectively. Clinical agreement regarding therapeutic range was present in 92.0% (POC within range), 67.7% (POC below range) and 87.6% (POC above range) of the paired measurements. We observed ≥15% INR difference between the POC and laboratory result in 14.8% (POC INR 2.0-4.0), 17.0% (POC INR<2.0) and 47.8% (POC INR >4.0) of the paired measurements.

CONCLUSIONS

POC and laboratory INR results were strongly correlated within the therapeutic range and differences between results become larger with increasing INR. Clinical disagreement between laboratory and POC results occurs often at both sub- and supratherapeutic INR levels.

Fresh frozen plasma transfusion fails to influence the hemostatic balance in critically ill patients with a coagulopathy

BACKGROUND

Coagulopathy has a high prevalence in critically ill patients. An increased International Normalized Ratio (INR) is a common trigger to transfuse fresh frozen plasma (FFP), even in the absence of bleeding. Therefore, FFP is frequently administered to these patients. However, the efficacy of FFP in correcting hemostatic disorders in non-bleeding recipients has been questioned.

OBJECTIVES

To assess whether INR prolongation parallels changes in the results of other tests investigating hemostasis, and to evaluate the coagulant effects of a fixed dose of FFP in non-bleeding critically ill patients with a coagulopathy.

METHODS

Markers of coagulation, individual factor levels and levels of natural anticoagulants were measured. Also, thrombin generation and thromboelastometry (ROTEM) assays were performed before and after FFP transfusion (12 mL kg(-1) ) to 38 non-bleeding critically ill patients with an increased INR (1.5-3.0).

RESULTS

At baseline, levels of factor II, FV, FVII, protein C, protein S and antithrombin were reduced, and thrombin generation was impaired. ROTEM variables were within reference ranges, except for a prolonged INTEM clot formation time. FFP transfusion increased the levels of coagulation factors (FII, 34% [interquartile range (IQR) 26-46] before vs. 44% [IQR 38-52] after; FV, 48% [IQR 28-76] before vs. 58% [IQR 44-90] after; and FVII, 25% [IQR 16-38] before vs. 37% [IQR 28-55] after), and the levels of anticoagulant proteins. Thrombin generation was unaffected by FFP transfusion (endogenous thrombin potential, 72% [IQR 51-88] before vs. 71% [IQR 42-89] after), whereas ROTEM EXTEM clotting time and maximum clot firmness slightly improved in response to FFP.

CONCLUSION

In non-bleeding critically ill patients with a coagulopathy, FFP transfusion failed to induce a more procoagulant state.

Lack of Association of Clinical Factors (SAMe-TT2R2) with CYP2C9/VKORC1 Genotype and Anticoagulation Control Quality

Background and Purpose

Advantages of new oral anticoagulations may be greater in atrial fibrillation (AF) patients of poor anticoagulation control with warfarin. The SAMe-TT₂R₂ scoring system, based on clinical variables, was recently developed to aid in identifying these patients. In this study, we investigated the association of this clinical composite score with genetic factors related warfarin dosing and the quality of anticoagulation control.

Methods

Clinical and genetic data were collected from 380 consecutive Korean patients with AF (CHA₂DS₂-VASc score, 3.5±1.8) who were followed for an average of 4 years. We evaluated factors associated with time in therapeutic range (TTR, INR 2-3), including the CYP2C9 and VKORC1 genotypes and the SAMe-TT₂R₂ score (Sex female, Age <60 years, Medical history [>two co-morbidities], Treatment [interacting drugs, e.g., amiodarone], Tobacco use within 2 years [doubled], and Race non-white [doubled]).

Results

The average SAMe-TT₂R₂ score was 3.4±0.9, range 2-7; and 153 patients (40.2%) had SAMe-TT₂R₂ scores ≥4. Time in specific INR ranges varied depending on the VKORC1 genotype but not with the CYP2C9 genotype or the SAMe-TT₂R₂ score. TTR was higher in patients with the VKORC1 1173C>T than in VKORC1 TT (61.7±16% vs. 56.7±17.4%, P=0.031). Multivariate testing showed that VKORC1 genotype but not the SAMe-TT₂R₂ score was significantly associated with labile INRs. There was no correlation between the SAMe-TT₂R₂ scores and pharmacogenetic data.

Conclusions

A genetic factor, but none of the common clinical and demographic factors, as combined in the SAMe-TT₂R₂ score, was associated with the quality of anticoagulation control in Korean patients with AF.

Effective and Safe Management of Oral Anticoagulation Therapy in Patients Who Use the Internet-Accessed Telecontrol Tool SintromacWeb

Background

Despite the existing evidence that highlights the benefits of oral anticoagulation therapy (OAT) self-testing and self-management by patients in comparison with conventional control, significant progress is still needed in the implementation of computer-based, Internet-assisted systems for OAT within health care centers. The telecontrol tool “SintromacWeb” is a previously validated system for OAT management at home, which is currently operative and accessed by patients through a hospital Web portal.

Objective

The intent of the study was to assess the effectiveness and safety of OAT management in patients using the SintromacWeb telecontrol system in reference to control in patients using the conventional system (management at the hematology department), in terms of time in therapeutic range (TTR) of International Normalized Ratio (INR).

Methods

In this observational prospective study, patients were identified by their physician and divided in two groups according to the OAT management system that they were already using (conventional control or telecontrol with SintromacWeb). For 6 months, patients were required to visit the hematology department every time their physician considered it necessary according to usual clinical practice. Sociodemographic and clinical variables for the study were collected at first visit (baseline) and at those visits closest to 2, 4, and 6 months after first visit.

Results

A total of 173 patients were evaluated, 87 with conventional control and 86 with telecontrol. Follow-up time was a median of 6.3 (range 5.2-8.1) months. The average time of OAT treatment prior to enrollment was 9.2 (SD 6.4) years. Patients in the telecontrol group tested their INR a median of 21 (range 4-22) days versus a median of 35 (range 14-45) days in patients in the conventional control group (P<.001). TTR in the telecontrol group was 107 (SD 37) days versus 94 (SD 37) days in the conventional control group (an increase of 12.6%; P=.02). In all visits, the percentage of TTR was higher in the telecontrol group (at the third visit: 59% vs 48%; P=.01). Higher TTR (positive coefficient) was associated with patients under OAT telecontrol (P=.03). Under-anticoagulation (INR<1.5) and over-anticoagulation (INR>5) were observed in 34 (19.7%, 34/173) and 38 (22.0%, 38/173) patients, respectively (no differences between treatment groups). Seven thrombotic and/or bleeding events were serious, 12 were non-serious, and most of them (5 and 10, respectively) occurred in the conventional control group.

Conclusions

In clinical practice, OAT management with the Internet-based tool SintromacWeb is effective and safe for those patients who are eligible for OAT telecontrol.

Extremely elevated international normalized ratio of warfarin in a patient with CYP2C9*1/*3 and thyrotoxicosis

A 73-yr-old Korean man with permanent atrial fibrillation visited outpatient clinic with severely increased International Normalized Ratio (INR) values after taking a usual starting dosage of warfarin to prevent thromboembolism. We found out later from his blood tests that he had hyperthyroidism at the time of treatment initiation. His genetic analysis showed CYP2C9*1/*3 and VKORC1+1173TT genotypes. We suspect that both hyperthyroidism and genetic variant would have contributed to his extremely increased INR at the beginning of warfarin therapy. From this case, we learned that pharmacogenetic and thyroid function test might be useful when deciding the starting dosage of warfarin in patients with atrial fibrillation.

Recombinant factor VIIa use in patients presenting with intracranial hemorrhage

Recombinant factor VIIa (rFVIIa) can be used for rapid INR normalization in life-threatening hemorrhage in anticoagulated patients. Dosing is unclear and may carry thromboembolic risks. We reviewed the use of rFVIIa at a comprehensive stroke and cerebrovascular center to evaluate dose effectiveness on INR reduction and thromboembolic complications experienced. The primary endpoint was to review the efficacy of rFVIIa in lowering INR. Secondary endpoints included doses used and adverse effects caused by rFVIIa administration. Forty-one percent of patients presented with a subdural hemorrhage. The mean INR prior to rFVIIa administration was 3.5 (0.9-15) and decreased to 1.13 (0.6-2). The mean dose of rFVIIa given was 73 mcg/kg (±24 mcg/kg). Two patients (3%) experienced a thromboembolic event. Recombinant factor VIIa appears to lower INR without significant thromboembolic complications.

An evaluation of the potential drug interaction between warfarin and levothyroxine

BACKGROUND

Drug interaction references report that initiation of levothyroxine potentiates the effects of warfarin, and recommend more frequent International Normalized Ratio (INR) monitoring, but the mechanism is not well understood.

OBJECTIVE

To assess the impact of levothyroxine initiation on INR response.

PATIENTS/METHODS

A retrospective, self-controlled study was performed on patients aged ≥ 18 years receiving chronic warfarin therapy who were started on levothyroxine between 1 January 2006 and 30 June 2013, and who were followed for 90 days prior to and after levothyroxine initiation. The included patients had at least one elevated thyroid-stimulating hormone laboratory value in the pre-period, continuous warfarin therapy for 100 days prior to levothyroxine initiation, no purchases of medications known to interact with warfarin, no procedures requiring warfarin interruption, and no bleeding or thromboembolic event during the study period. The primary outcome was a comparison of the warfarin dose/INR ratio recorded before the initiation of levothyroxine with the ratio recorded during the post-period after two consecutive INRs with no warfarin dose change.

RESULTS

One hundred and two patients were included in the primary outcome. The mean warfarin dose/INR ratios in the pre-period and post-period were equivalent (P = 0.825). Although the mean warfarin dose was numerically lower in the post-period than in the pre-period, this difference did not reach statistical significance (P = 0.068).

CONCLUSION

No difference in the mean warfarin dose/INR ratio before and after initiation of levothyroxine was detected. The results suggest that there is not a clinically significant interaction between warfarin and levothyroxine, and so additional monitoring may not be necessary.

Management of Bleeding in Post-liver Disease, Surgery and Biopsy in Patients With High Uncorrected International Normalized Ratio With Prothrombin Complex Concentrate: An Iranian Experience

Background:

To evaluate the efficacy of prothrombin complex concentrate (PCC) in the management of bleeding in patients with liver disease and patients undergoing surgery or biopsy who had a high uncorrected international normalized ratio (INR).

Objectives:

In this study, we examined an Iranian sample and investigated the efficacy of PCC to manage bleeding in patients with liver disease and also patients with high uncorrected INR who were scheduled for surgery or biopsy.

Materials and Methods:

A total of 25 patients including 16 patients with post-liver disease bleeding (group 1) and 9 patients with high uncorrected INR who were scheduled for surgery or biopsy (group 2) were enrolled. All patients were treated with 25 IU/kg PCC, and efficacy was defined as any reduction in or cessation of bleeding episodes and correction of INR before surgery or biopsy. The patients were also evaluated for any adverse effects.

Results:

INR decreased significantly in both groups of patients, with no bleeding episodes during or after the study in group 1 and during or after surgery/biopsy in group 2. All patients tolerated the therapy well without any significant adverse effects.

Conclusions:

The efficacy of PCC therapy was satisfactory in this study. PCC therapy in patients with liver disease and patients undergoing surgery or biopsy seems to be effective and safe, and may be a good treatment strategy for these patients, if fresh frozen plasma or vitamin K are not effective.

A descriptive evaluation of warfarin use in patients with pulmonary arterial hypertension

INTRODUCTION

Although warfarin is often recommended for pulmonary arterial hypertension (PAH) management to mitigate thrombotic risk and improve survival, limited information exists to guide anticoagulation therapy. The purpose of this study was to compare and contrast warfarin therapy monitoring requirements and outcomes in patients with PAH and atrial fibrillation (AF) receiving long-term anticoagulation.

MATERIALS AND METHODS

Patients initiated on warfarin for PAH between January 1, 2000 and December 31, 2008 were matched by warfarin initiation date (±90 days), age (±5 years), chronic disease score (±1 points), and sex to patients initiated for AF. The primary study endpoint was frequency of INR monitoring per 30 days of observation. Secondary endpoints included indicators of INR control and warfarin-related adverse events.

RESULTS AND CONCLUSION

A total of 84 patients were included - 18 and 66 in the PAH and AF groups, respectively. Patients with PAH had a higher median rate of INR measurements per 30 days compared to patients with AF (median=2.0, interquartile range [IQR]=1.5 - 2.3 vs. median=1.6, IQR=1.3 - 2.0, p=0.046). There were no differences between groups with respect to percent of INR measurements in range, overall time in therapeutic range (TTR), or warfarin-related adverse events (all p>0.05). Study results suggest that patients with PAH may be more difficult to manage as seen through more frequent INR monitoring. Potential management difficulties did not translate to a lower performance on indicators of INR control or increased risk of warfarin-related adverse events.

Characteristics, risk factors, and mortality of cirrhotic patients hospitalized for hepatic encephalopathy with and without acute-on-chronic liver failure (ACLF)

BACKGROUND & AIMS

In spite of the high incidence of hepatic encephalopathy (HE) in cirrhosis, there are few observational studies.

METHODS

We performed an analysis to define the characteristics of HE and associated features using the database of the Canonic Study. Clinical, laboratory and survival data of 1348 consecutive cirrhotic patients admitted with an acute decompensation were compared according to the presence (n=406) or absence of HE and of acute-on-chronic liver failure (ACLF) (n=301).

RESULTS

HE development was independently associated with previous HE episodes; survival probabilities worsen in relation to the presence and grade of HE. There were marked differences between HE associated (n=174) and not associated (n=286) to ACLF. HE not associated with ACLF occurred in older cirrhotics, inactive drinkers, without severe liver failure or systemic inflammatory reaction and in relation to diuretic use. In contrast, HE associated with ACLF occurred in younger cirrhotics, more frequently alcoholics, with severe liver failure and systemic inflammatory reaction, and in relation to bacterial infections, active alcoholism and/or dilutional hyponatremia. Prognosis was relatively preserved in the first and extremely poor in the second group. Independent risk factors of mortality in patients with HE were age, bilirubin, INR, creatinine, sodium, and HE grade.

CONCLUSIONS

In cirrhosis, previous HE identifies a subgroup of patients that is especially vulnerable for developing new episodes of HE. The course of HE appears to be different according to the presence of ACLF.

Safety and efficacy of protease inhibitors to treat hepatitis C after liver transplantation: a multicenter experience

BACKGROUND & AIMS

Protease inhibitors (PI) with peginterferon/ribavirin have significantly improved SVR rates in HCV G1 patients. Their use to treat HCV recurrence after liver transplantation (LT) is a challenge.

METHODS

This cohort study included 37 liver transplant recipients (male, 92%, age 57 ± 11 years), treated with boceprevir (n=18) or telaprevir (n=19). The indication for therapy was HCV recurrence (fibrosis stage ≥F2 (n=31, 83%) or fibrosing cholestatic hepatitis (n=6, 16%).

RESULTS

Eighteen patients were treatment-naive, five were relapsers and fourteen were non-responders to dual therapy after LT. Twenty-two patients received cyclosporine and fifteen tacrolimus. After 12 weeks of PI therapy, a complete virological response was obtained in 89% of patients treated with boceprevir, and 58% with telaprevir (p=0.06). The end of treatment virological response rate was 72% (13/18) in the boceprevir group and 40% (4/10) in the telaprevir group (p=0.125). A sustained virological response 12 weeks after treatment discontinuation was observed in 20% (1/5) and 71% (5/7) of patients in the telaprevir and boceprevir groups, respectively (p=0.24). Treatment was discontinued in sixteen patients (treatment failures (n=11), adverse events (n=5)). Infections occurred in ten patients (27%), with three fatal outcomes (8%). The most common adverse effect was anemia (n=34, 92%), treated with erythropoietin and/or a ribavirin dose reduction; thirteen patients (35%) received red blood cell transfusions. The cyclosporine dose was reduced by 1.8 ± 1.1-fold and 3.4 ± 1.0-fold with boceprevir and telaprevir, respectively. The tacrolimus dose was reduced by 5.2 ± 1.5-fold with boceprevir and 23.8±18.2-fold with telaprevir.

CONCLUSIONS

Our results suggest that triple therapy is effective in LT recipients, particularly those experiencing a severe recurrence. The occurrence of anemia and drug-drug interactions, and the risk of infections require close monitoring.

Use of intravenous recombinant tissue plasminogen activator in patients with borderline elevation of international normalized ratio

OBJECTIVE

To determine the rates of symptomatic intracerebral hemorrhages (sICH), parenchymal hematoma type 2 (PH2), and favorable outcomes in patients with borderline elevation of international normalized ratio (INR) or recent anticoagulation use prior to treatment with intravenous recombinant tissue plasminogen activator (IV rt-PA) for acute ischemic stroke.

METHODS

Consecutive patients with acute ischemic stroke that received IV rt-PA were identified. History of recent use of anticoagulation and the INR at presentation and after use of thrombolytics, up to 72 h was recorded. Neuroimaging and clinical charts were reviewed for evidence of sICH. Outcomes were recorded at the time of discharge and on follow-up up to 6 months using the modified Rankin scale (mRS).

RESULTS

A total of 106 patients (mean age was 65.95 ± 15.29 years and 55.67% were men) were identified. Of these, 12 (11.3%) patients had initial INR elevation (1.2-1.7) and 12 (11.3%) patients that had recently received oral anticoagulation. The rate of PH2 was higher in patients on anticoagulation or with elevated initial INR compared to patients with normal INR and no history of anticoagulation (15.79% versus 2.30%, P = 0.023). In subgroup analyses, elevation of INR during the first 24 h and history of recent use of anticoagulation in a different analysis inversely correlated with favorable outcomes at discharge and at follow-up.

CONCLUSION

Borderline elevation in INR or recent use of anticoagulation before thrombolytic use can increase the rate of ICH in patients treated with IV rt-PA for acute ischemic stroke. These patients should cautiously receive thrombolytics for acute ischemic stroke as per the AHA/ASA Stroke Council guidelines.

Demonstration of anticoagulation patient self-testing feasibility at an Indian Health Service facility: A case series analysis

Background

Anticoagulation patient self-testing (PST) represents an alternative approach to warfarin monitoring by enabling patients to use coagulometers to test their international normalized ratio (INR) values. PST offers several advantages that potentially improve warfarin management.

Objective

To describe implementation and associated performance of a PST demonstration program at an Indian Health Service (IHS) facility.

Methods

A non-consecutive case series analysis of patients from a pharmacy-managed PST demonstration program was performed at an IHS facility in Oklahoma between July 2008 and February 2009.

Results

Mean time in therapeutic range (TTR) for the seven patients showed a small, absolute increase during the twelve weeks of PST compared to the twelve weeks prior to PST. Four of the seven patients had an increase in TTR during the twelve week course of PST compared to their baseline TTR. Three of four patients with increased TTR in the final eight week period of PST achieved a TTR of 100%. Of the three patients who experienced a decrease in TTR after initiating self-testing, two initially presented with a TTR of 100% prior to PST and one patient had a TTR of 100% for the final eight weeks of PST. The two patients not achieving a TTR of 100% during the twelve week PST period demonstrated an increase in TTR following the first four weeks of PST.

Conclusions

Although anticoagulation guidelines now emphasize patient self-management (PSM) only, optimal PST remains an integral process in PSM delivery. In the patients studied, the results of this analysis suggest that PST at the IHS facility provided a convenient, alternative method for management of chronic warfarin therapy for qualified patients. More than half of the patients demonstrated improvement in TTR. Although there is a learning curve immediately following PST initiation, the mean TTR for the entire PST period increased modestly when compared to the time period prior to PST.

Comparison of the survival and tolerability of radioembolization in elderly vs. younger patients with unresectable hepatocellular carcinoma

BACKGROUND & AIMS

The European Network on Radioembolization with Yttrium-90 resin microspheres study group (ENRY) conducted a retrospective study to evaluate the outcomes among elderly (≥ 70 years) and younger patients (<70 years) with unresectable hepatocellular carcinoma (HCC) who received radioembolization at 8 European centers.

METHODS

Patients with confirmed diagnosis of unresectable HCC who either progressed following resection or locoregional treatment and/or who were considered poor candidates for chemoembolization were evaluated by a multidisciplinary team for radioembolization with (90)Y-resin microspheres (SIR-Spheres; Sirtex Medical). The survival outcome and all adverse events were compared between the two age groups.

RESULTS

Between 2003 and 2009, 128 elderly and 197 younger patients received radioembolization. Patients in both groups had similar demographic characteristics. Many elderly and younger patients alike had multinodular, BCLC stage C disease, invading both lobes (p = 0.648). Elderly patients had a lower tumor burden, a smaller median target liver volume (p = 0.016) and appeared more likely to receive segmental treatment (p = 0.054). Radioembolization was equally well tolerated in both cohorts and common procedure-related adverse events were predominantly grade 1-2 and of short duration. No significant differences in survival between the groups were found (p = 0.942) with similar median survival in patients with early, intermediate or advanced BCLC stage disease.

CONCLUSIONS

Radioembolization appears to be as well-tolerated and effective for the elderly as it is for younger patients with unresectable HCC. Age alone should not be a discriminating factor for the management of HCC patients.

The clinical evaluation of International Normalized Ratio variability and control in conventional oral anticoagulant administration by use of the variance growth rate

INTRODUCTION

The time in target International Normalized Ratio (INR) range (TIR) is used to assess the control and intensity of oral anticoagulation, but it does not measure variation in the INR.

OBJECTIVES

The value of assessing INR variability by use of the variance growth rate (VGR) as a predictor of events was investigated in patients treated with warfarin.

METHODS

Three different methods of VGR determination (A, B1, and B2) together with the TIR were studied. Method A measures both INR variability and control, but methods B1 and B2 measure variability only. The VGR and TIR were determined over three time periods: overall follow-up to an event, and 6 months and 3 months before an event.

RESULTS

Six hundred and sixty-one control patients were matched to 158 cases (bleeding, thromboembolism, or death). With all VGR methods, the risk of an event was greater in unstable patients at 6 months before an event than in stable patients. Method A demonstrated the greatest risk 3 months before an event in the unstable VGR group as compared with the stable group (odds ratio 3.3, 95% confidence interval 1.9-5.7, P < 0.005). The risk of an event was 1.9 times greater in patients with a low TIR (< 39%) than in those with a high TIR (> 80%) in the 3-month period (P = 0.02). Risk of bleeding was significantly greater in the 3-month period in patients with unstable VGR, with the greatest risk found with method B2 (P < 0.01).

CONCLUSIONS

Patients with unstable anticoagulation have a significantly increased risk of 'clinical events' at 3 and 6 months before an event. The VGR can be incorporated into computer-dosage programs, and may offer additional safety when oral anticoagulation is monitored.

[Economic evaluation of dabigatran for stroke prevention in patients with non-valvular atrial fibrillation]

INTRODUCTION AND OBJECTIVES

To estimate the cost-effectiveness and cost-utility of dabigatran in the prevention of stroke and systemic embolism in patients with non-valvular atrial fibrillation in Portugal.

METHODOLOGY

A Markov model was used to simulate patients' clinical course, estimating the occurrence of ischemic and hemorrhagic stroke, transient ischemic attack, systemic embolism, myocardial infarction, and intra- and extracranial hemorrhage. The clinical parameters are based on the results of the RE-LY trial, which compared dabigatran with warfarin, and on a meta-analysis that estimated the risk of each event in patients treated with aspirin or with no antithrombotic therapy.

RESULTS

Dabigatran provides an increase of 0.331 life years and 0.354 quality-adjusted life years for each patient. From a societal perspective, these clinical gains entail an additional expenditure of 2978 euros. Thus, the incremental cost is 9006 euros per life year gained and 8409 euros per quality-adjusted life year.

CONCLUSIONS

The results show that dabigatran reduces the number of events, especially the most severe such as ischemic and hemorrhagic stroke, as well as their long-term sequelae. The expense of dabigatran is partially offset by lower event-related costs and by the fact that INR monitoring is unnecessary. It can thus be concluded that the use of dabigatran in clinical practice in Portugal is cost-effective.

Whole blood rotation thromboelastometry (ROTEM®) profiles in subjects with non-neoplastic portal vein thrombosis

The coagulation pattern and the determinants of portal vein thrombosis (PVT), both in patients with and without cirrhosis, are still largely unknown. The aim of this study was to evaluate whole blood thromboelastometry profile, performed by ROTEM®, of both cirrhotic and non-cirrhotic subjects with PVT. Two different groups were considered: i) 14 non-cirrhotic PVT patients, ii) 35 cirrhotic patients with PVT. Controls were sex- and age-matched healthy volunteers and cirrhotic subjects without PVT, respectively. ROTEM® assays (i.e. INTEM, EXTEM, NATEM, and FIBTEM) and traditional coagulative parameters (i.e. platelet count, PT/INR, aPTT, and fibrinogen) were performed on blood samples from each subject. There were no significant differences in ROTEM® profile, as for INTEM, EXTEM, and NATEM assays, and in traditional coagulative parameters, between PVT patients, both with and without cirrhosis, and control groups. Interestingly, Maximum Clot Firmness (MCF) in FIBTEM was significantly higher in non-cirrhotic PVT patients (19 mm) than in healthy volunteers (11 mm, p<0.05). The amplitude of MCF in FIBTEM revealed to be a useful tool to discriminate non-cirrhotic subjects with PVT from those without thrombotic events. Larger prospective studies are needed to evaluate the relevance of the association between the alterations of ROTEM® profiles and PVT in cirrhotic patients.

Nonadherence with INR monitoring and anticoagulant complications

INTRODUCTION

This study tests the hypothesis that nonadherence with INR monitoring is associated with an increased risk for warfarin-related bleeding and thrombosis and describes patient characteristics associated with INR monitoring nonadherence.

MATERIALS AND METHODS

This was a retrospective, longitudinal, matched cohort study wherein patients were categorized into adherent and nonadherent cohorts; adherent patients were matched 2:1 to nonadherent patients. The primary study endpoint was the first occurrence of bleeding or thromboembolism. Multivariate logistic regression modeling identified patient characteristics associated with INR monitoring adherence or nonadherence.

RESULTS

A total of 4995 and 2544 patients contributed 10729 and 5385 patient-years of warfarin therapy in the adherent and nonadherent groups, respectively. The rate of thromboembolic events during follow up was higher in the nonadherent group than in the adherent group (0.95% vs. 0.62% per patient-year, respectively; p=0.019) and nonadherence to INR monitoring was associated with a moderately higher risk of thromboembolism (adjusted Hazard Ratio=1.51; 95% confidence interval=1.04 - 2.20). The difference in bleeding between the two groups was not statistically significant.

CONCLUSIONS

Repeatedly missing INR tests is an easily identified clinical parameter that is associated with moderately increased risk for thromboembolism in patients taking chronic warfarin therapy. Clinicians should carefully consider the underlying thromboembolic risk and extent of nonadherence when weighing the benefits of continued warfarin therapy for a given patient.

Effect of low-dose supplements of menaquinone-7 (vitamin K2 ) on the stability of oral anticoagulant treatment: dose-response relationship in healthy volunteers

BACKGROUND AND OBJECTIVE

Despite the worldwide use of vitamin K antagonists (VKAs), there is limited knowledge of the influence of dietary vitamin K on anticoagulation control. In view of the increasing nutraceutical availability of menaquinone-7 (MK-7; vitamin K2 ) and its promotion for bone and cardiovascular health, it is important to determine the posology for the interference of supplemental MK-7 with VKA therapy.

PATIENTS

Eighteen healthy men and women were anticoagulated for 4 weeks with acenocoumarol, and 15 of them attained a target International Normalized Ratio (INR) of 2.0. In the six subsequent weeks, subjects were given increasing doses of MK-7 (10, 20 and 45 μg day(-1) ) while continuing acenocoumarol treatment at established individual doses.

RESULTS

Apart from the INR, acenocoumarol treatment significantly increased the levels of uncarboxylated factor II (ucFII), uncarboxylated osteocalcin (ucOC), and desphospho-uncarboxylated matrix Gla-protein (dp-ucMGP), and decreased endogenous thrombin generation (ETP). A daily intake of 45 μg of MK-7 significantly decreased the group mean values of both the INR and ucFII by ~ 40%. Daily intakes of 10 and 20 μg of MK-7 were independently judged by two hematologists to cause a clinically relevant lowering of the INR in at least 40% and 60% of subjects, respectively, and to significantly increase ETP by ~ 20% and ~ 30%, respectively. Circulating ucOC and dp-ucMGP were not affected by MK-7 intake.

CONCLUSIONS

MK-7 supplementation at doses as low as 10 μg (lower than the usual retail dose of 45 μg) significantly influenced anticoagulation sensitivity in some individuals. Hence, the use of MK-7 supplements needs to be avoided in patients receiving VKA therapy.

Use of Prothrombin Complex Concentrate for Vitamin K Antagonist Reversal before Surgical Treatment of Intracranial Hemorrhage

Background:

Oral anticoagulant therapy (OAT) is used to prevent/treat thromboembolism. Major bleeding is common in patients on OAT; eg, warfarin increases intracranial hemorrhage (ICH) risk.

Case:

A 71-year-old male on warfarin (to reduce stroke risk) presented at Accident and Emergency Minor Injuries Unit with headache after reportedly sounding ‘drunk’. On triage, the patient appeared lucid and well. However, International Normalized Ratio (INR) was 4.1. Head computed tomography (CT) indicated a large right-sided subdural hematoma. Prothrombin complex concentrate (PCC; Beriplex^® P/N, CSL Behring) with vitamin K normalized the INR within minutes of administration. The patient underwent neurosurgery without complications, and was discharged after 5 days, with no residual neurological symptoms.

Conclusions:

ICH patients can present with no neurological signs. In OAT patients with headache, INR must be established; if ≥3.0, normalization of INR and head CT are essential. PCC is the best option to rapidly reverse anticoagulation and correct INR pre-surgery.