The reliability of point-of-care prothrombin time testing. A comparison of CoaguChek S and XS INR measurements with hospital laboratory monitoring

Microfluidics chips fabrication techniques comparison

This study investigates various microfluidic chip fabrication techniques, highlighting their applicability and limitations in the context of urgent diagnostic needs showcased by the COVID-19 pandemic. Through a detailed examination of methods such as computer numerical control milling of a polymethyl methacrylate, soft lithography for polydimethylsiloxane-based devices, xurography for glass-glass chips, and micromachining-based silicon-glass chips, we analyze each technique's strengths and trade-offs. Hence, we discuss the fabrication complexity and chip thermal properties, such as heating and cooling rates, which are essential features of chip utilization for a polymerase chain reaction. Our comparative analysis reveals critical insights into material challenges, design flexibility, and cost-efficiency, aiming to guide the development of robust and reliable microfluidic devices for healthcare and research. This work underscores the importance of selecting appropriate fabrication methods to optimize device functionality, durability, and production efficiency.

Foldable low-cost point-of-care device for testing blood coagulation using smartphones

Cardiovascular diseases (CVDs) caused by thrombotic events are a significant global health concern, affecting millions of people worldwide. The international normalized ratio (INR) is the most widely used measure of coagulation status, and frequent testing is required to adjust blood-thinning drug dosage, requiring hospital visits and experts to perform the test. Here we present a low-cost and portable smartphone-based device for screening INR levels from whole blood samples at the point of care. Our device uses a 3D printed platform and light-emitting diode backlight modules to create a uniform optical environment, and its foldable design allows for easy transport. Our device also features an algorithm that allows users to acquire and process video of sample flow in a microfluidic channel on their smartphone, providing a cost-effective and convenient option for blood coagulation monitoring at the point of care. We tested the performance of our smartphone-based INR device using both commercially available control samples and clinical human blood samples, demonstrating high accuracy and reliability. Our device has the potential to improve patient outcomes by enabling more frequent monitoring and, as appropriate, dosage adjustments of blood-thinning drugs, providing an affordable and portable option for screening INR levels at the point of care.

Replicate Testing of Clinical Endpoints Can Prevent No-Go Decisions for Beneficial Vaccines

In vaccine efficacy trials, inaccurate counting of infection cases leads to systematic under-estimation-or "dilution"-of vaccine efficacy. In particular, if a sufficient fraction of observed cases are false positives, apparent efficacy will be greatly reduced, leading to unwarranted no-go decisions in vaccine development. Here, we propose a range of replicate testing strategies to address this problem, considering the additional challenge of uncertainty in both infection incidence and diagnostic assay specificity/sensitivity. A strategy that counts an infection case only if a majority of replicate assays return a positive result can substantially reduce efficacy dilution for assays with non-systematic (i.e., "random") errors. We also find that a cost-effective variant of this strategy, using confirmatory assays only if an initial assay is positive, yields a comparable benefit. In clinical trials, where frequent longitudinal samples are needed to detect short-lived infections, this "confirmatory majority rule" strategy can prevent the accumulation of false positives from magnifying efficacy dilution. When widespread public health screening is used for viruses, such as SARS-CoV-2, that have non-differentiating features or may be asymptomatic, these strategies can also serve to reduce unneeded isolations caused by false positives.

Accuracy and Precision of Point-of-Care International Normalized Ratio in Patients With Liver Disease

OBJECTIVE

To determine if the CoaguChek XS Pro Point-of-Care (POC) device can accurately and precisely measure the international normalized ratio (INR) compared with the gold standard laboratory INR in pediatric and adult patients with liver disease.

METHODS

This prospective cohort study included 15 pediatric patients without liver disease, 13 pediatric patients with liver disease, and 17 adult patients with liver disease. The accuracy of the POC INR values was determined using the correlation and Bland-Altman limits of agreement. The accuracy of the coagulometer INR was assessed by calculating the proportion of POC INR measurements that were ≤15% of their corresponding laboratory INR.

RESULTS

A comparison of INR measurements showed an excellent correlation in pediatric patients without liver disease ( r = 0.82), pediatric patients with liver disease ( r = 0.89), and adult patients with liver disease ( r = 0.96). Fourteen (93%) POC INR values were ≤15% in pediatric patients without liver disease from its paired laboratory INR. All 13 paired measurements were ≤15% in pediatric patients with liver disease. In adult patients with liver disease, 12 (71%) POC INR values were ≤15% of their paired laboratory INR.

CONCLUSIONS

In patients with liver disease, the CoaguChek XS Pro provides an accurate measure of the INR compared to laboratory INR measurements.

Reliability of International Normalized Ratio Results in the CoaguChek Pro II System in a Clinical Setting

The National Institute of Cardiology has previously used the CoaguChek® XS Plus system (Roche Diagnostics International Ltd), comparing capillary blood prothrombin time/international normalized ratio (PT/INR) results with those obtained using BCS-XP/Thromborel (Siemens). We assessed the reliability of PT/INR results using the third-generation CoaguChek Pro II system, the CoaguChek XS Plus system, and cobas® t 411 for citrated plasma analysis. Venous and capillary PT/INR were measured (N = 204). Spearman's correlation, Bland-Altman, and concordance analysis between methods were conducted. Spearman's correlation coefficients between venous/capillary INR were high for CoaguChek Pro II versus CoaguChek XS Plus (r = 0.994), CoaguChek Pro II versus cobas t 411 (r = 0.967), and CoaguChek XS Plus versus cobas t 411 (r = 0.968). Good concordance was observed among capillary methods (concordance coefficient [κ] = 0.888) and remaining relationships (P < .001 for all): cobas t 411 versus CoaguChek XS Plus (κ = 0.696) and cobas t 411 versus CoaguChek Pro II (κ = 0.684). In conclusion, good agreement was observed between CoaguChek Pro II, CoaguChek XS Plus, and cobas t 411.

The Choice between Plasma-Based Common Coagulation Tests and Cell-Based Viscoelastic Tests in Monitoring Hemostatic Competence: Not an either-or Proposition

There has been a significant interest in the last decade in the use of viscoelastic tests (VETs) to determine the hemostatic competence of bleeding patients. Previously, common coagulation tests (CCTs) such as the prothrombin time (PT) and partial thromboplastin time (PTT) were used to assist in the guidance of blood component and hemostatic adjunctive therapy for these patients. However, the experience of decades of VET use in liver failure with transplantation, cardiac surgery, and trauma has now spread to obstetrical hemorrhage and congenital and acquired coagulopathies. Since CCTs measure only 5 to 10% of the lifespan of a clot, these assays have been found to be of limited use for acute surgical and medical conditions, whereby rapid results are required. However, there are medical indications for the PT/PTT that cannot be supplanted by VETs. Therefore, the choice of whether to use a CCT or a VET to guide blood component therapy or hemostatic adjunctive therapy may often require consideration of both methodologies. In this review, we provide examples of the relative indications for CCTs and VETs in monitoring hemostatic competence of bleeding patients.

Point of care testing to monitor INR control in patients with antiphospholipid syndrome

Patients with antiphospholipid syndrome (APS) typically require lifelong warfarin anticoagulation following a thrombotic event due to a significant risk of recurrent thrombosis. Point of care testing (POCT) to monitor INR is discouraged in patients with APS as interactions between antiphospholipid antibodies and thromboplastin used for INR testing may influence results. Review of INR testing in 36 APS patients showed 87.2% of paired POCT and venous INRs (n = 94) having acceptable variation (≤0.5 difference), and high correlation (r = 0.9) excluding INRs ≥4.8. Six-month TTR was comparable for APS patients using POCT (57.1% ± 24.8%) to those using venous INR monitoring (59.2% ± 23.2%) (p = 0.66). These results support POCT management of APS but requires further study.

Micro-mechanical blood clot testing using smartphones

Frequent prothrombin time (PT) and international normalized ratio (INR) testing is critical for millions of people on lifelong anticoagulation with warfarin. Currently, testing is performed in hospital laboratories or with expensive point-of-care devices limiting the ability to test frequently and affordably. We report a proof-of-concept PT/INR testing system that uses the vibration motor and camera on smartphones to track micro-mechanical movements of a copper particle. The smartphone system computed the PT/INR with inter-class correlation coefficients of 0.963 and 0.966, compared to a clinical-grade coagulation analyzer for 140 plasma samples and demonstrated similar results for 80 whole blood samples using a single drop of blood (10 μl). When tested with 79 blood samples with coagulopathic conditions, the smartphone system demonstrated a correlation of 0.974 for both PT/INR. Given the ubiquity of smartphones in the global setting, this proof-of-concept technology may provide affordable and effective PT and INR testing in low-resource environments.

Therapy with anticoagulants requires frequent monitoring. Here the authors describe a proof-of-concept study of a simple and affordable blood clot test that uses a smartphone’s vibration motor and camera to track micro-movements in a single drop of blood.

Benefits and Pitfalls of Point-of-Care Coagulation Testing for Anticoagulation Management: An ACLPS Critical Review

Objectives

Point-of-care (POC) testing is generally less precise and has higher reagent costs per test than laboratory-based assays. However, POC hemostasis testing can offer significant advantages in particular situations: patient-managed warfarin therapy as well as rapid turnaround time heparin management for intraoperative patients. Of note, POC hemostasis testing is generally approved for the purposes of anticoagulation monitoring and is inferior to laboratory coagulation testing for the diagnosis of congenital or acquired coagulopathy.

Methods

The frequently used POC coagulation instruments for POC international normalized ratio and activated clotting time are reviewed, as well as their typical performance relative to central laboratory testing (where available).

Results

Several cases are discussed that highlight the benefits, as well as pitfalls, of POC coagulation testing.

Conclusions

POC coagulation testing for anticoagulation monitoring offers advantages in particular situations. Clear policies and protocols must be developed to guide proper use of POC versus central laboratory hemostasis testing.

Verification of the qLabs international normalized ratio point-of-care device for monitoring of patients attending an anticoagulation clinic

INTRODUCTION

In the developing world, point-of-care (POC) testing for international normalized ratio (INR) plays an important role in the monitoring of patients on long-term warfarin therapy with limited access to healthcare ensuring safe and effective anticoagulation. A newly developed POC device for INR measurement by healthcare workers is the handheld qLabs POC device^® (Micropoint Biotechnologies Incorporated, Guangdong, China).

METHODS

The qLabs POC device^® was evaluated in 262 patients attending an anticoagulation clinic with regards to accuracy and precision of the INR results. The results were compared to the results obtained on the Stago STA R Max^® coagulation analyzer (Stago Diagnostica, Paris, France) on a wide range of normal and abnormal results of clinical relevance.

RESULTS

The mean laboratory INR (2.50 ± 1.08) was significantly higher than the qLabs POC device^® INR (2.38 ± 1.07) (P < .0001). The correlation coefficient (r) was .88, the slope coefficient was 1.0 (CI, 0.8-1.2), and the intercept was -0.10 (CI, -0.50 to 0.30). The mean of the differences was -0.13% (CI, -0.19 to -0.06). Dosage concordance was 85.46% and clinical agreement was 92.37%. However, clinical agreement was 42.42% in the subgroup above the target range (>3.5). The imprecision was within acceptable limits (<5%) and the error message rate was 4.38%.

CONCLUSION

In conclusion, the qLabs POC device^® is accurate and precise with high levels of dosage concordance and clinical agreement for INR values within and below the target range.

Clinical Validation of R-T Estimation for CoaguChek XS INR Results

BACKGROUND

Despite the emergence of several new oral anticoagulants, warfarin remains a widely used form of anticoagulation that continues to have a role in the treatment of cardiac and thrombotic conditions.

OBJECTIVE

The goal of this study was to evaluate whether the R-T estimation, an equation developed in a previous study, was a valid clinical tool in managing patients' warfarin therapy in an anticoagulation clinic in lieu of obtaining a venipuncture international normalized ratio (INR) secondary to a high CoaguChek XS (CXS) INR.

METHODS

This study used a randomized double-blind method to compare the clinical decisions made using venipuncture or CXS machine and recorded the INR, percentage dose change, time to clinical decision from check-in, and scheduled follow-up.

RESULTS

In the analysis of the difference in percentage dose change, a 1.0% (95% CI = -0.78 to 2.68; P = 0.27) difference was observed overall, and a 1.2% (95% CI = -0.59 to 2.95; P = 0.18) difference was observed in the 4 to 5.9 subgroup. Clinical decisions were reached 17 minutes faster (95% CI = 11-24; P < 0.001) overall and 17 minutes faster (95% CI = 10-24; P < 0.001) in the 4 to 5.9 subgroup. Scheduled follow-up was 0.38 weeks sooner (95% CI = 0.01-0.67; P = 0.014) overall and 0.36 weeks sooner (95% CI = 0-0.66; P = 0.041) in the 4 to 5.9 subgroup.

CONCLUSIONS

The results of this study support the use of the R-T estimation for correction of INR values obtained using the CXS meter when the INR is in the range of 4 to 5.9. This correction will allow clinics using this device to more efficiently manage patients taking warfarin.

Correction of Point-of-Care INR Results in Warfarin Patients

BACKGROUND

The measurement of international normalization ratio (INR) may be done by venous blood draw and use of a standard lab, or by fingerstick, using a point of care (POC) device such as the CoaguChek XS® (Roche Diagnostics), and the CoaguChek XS® has been validated to meet the International Organization for Standardization (ISO) performance requirements.

OVERVIEW

The goal of this study was to determine a correction factor for Coaguchek XS INR levels to a predicted venipuncture (VP) INR level.

METHODS

At the end of an anticoagulation clinic visit when a patient had an INR greater than or equal to 4, two INR results existed, that from the Coaguchek XS® meter and a venipuncture INR from the lab. The data were then discreetly recorded as a quality control for our clinic. The data were analyzed for possible significant trends between the two types of INR results.

RESULTS

The equation that was determined to be the best fit to the data was 0.621 × POC + 0.639 = estimated VP. The overall root mean square error (MSE) for the calculated correction was a 0.44 INR. The root mean square errors were 0.41 and 0.58 for the 4 to 5.9 and 6 to 7.9 POC INR groups, respectively.

CONCLUSION

The calculation that was derived in this study is not a surrogate for venipuncture INR in this clinic. However, the estimation of the INR may be useful clinically in guiding decision making in the future. (INR, Point of Care, Anticoagulation, Hematology).

Coagulopathy and transfusion therapy in pediatric liver transplantation

Bleeding and coagulopathy are critical issues complicating pediatric liver transplantation and contributing to morbidity and mortality in the cirrhotic child. The complexity of coagulopathy in the pediatric patient is illustrated by the interaction between three basic models. The first model, "developmental hemostasis", demonstrates how a different balance between pro- and anticoagulation factors leads to a normal hemostatic capacity in the pediatric patient at various ages. The second, the "cell based model of coagulation", takes into account the interaction between plasma proteins and cells. In the last, the concept of "rebalanced coagulation" highlights how the reduction of both pro- and anticoagulation factors leads to a normal, although unstable, coagulation profile. This new concept has led to the development of novel techniques used to analyze the coagulation capacity of whole blood for all patients. For example, viscoelastic methodologies are increasingly used on adult patients to test hemostatic capacity and to guide transfusion protocols. However, results are often confounding or have limited impact on morbidity and mortality. Moreover, data from pediatric patients remain inadequate. In addition, several interventions have been proposed to limit blood loss during transplantation, including the use of antifibrinolytic drugs and surgical techniques, such as the piggyback and lowering the central venous pressure during the hepatic dissection phase. The rationale for the use of these interventions is quite solid and has led to their incorporation into clinical practice; yet few of them have been rigorously tested in adults, let alone in children. Finally, the postoperative period in pediatric cohorts of patients has been characterized by an enhanced risk of hepatic vessel thrombosis. Thrombosis in fact remains the primary cause of early graft failure and re-transplantation within the first 30 d following surgery, and it occurs despite prolongation of standard coagulation assays. Data, however, are currently lacking regarding the use of anti-aggregation/anticoagulation therapies and how to best monitor for thrombosis in the early postoperative period in pediatric patients. Therefore, further studies are necessary to elucidate the interaction between the development of the coagulation system and cirrhosis in children. Moreover, strategies to optimize blood transfusion and anticoagulation must be tested specifically in pediatric patients. In conclusion, data from the adult world can be translated with difficulty into the pediatric field as indication for transplantation, baseline pathologies and levels of pro- and anticoagulation factors are not comparable between the two populations.

Analytical performance of a point-of-care device in monitoring patients on oral anticoagulation with vitamin K antagonists

BACKGROUND

[Please check the following sentence for clarity: "Point-of-care devices measuring international normalized ratio have clinical appeal, reports of 'off-label' in-hospital/primary care use report improved time to intervention/dose adjustment."]Point-of-care devices measuring international normalized ratio have clinical appeal, reports of 'off-label' in-hospital/primary care use report improved time to intervention/dose adjustment. We evaluated the accuracy and precision of a device for such multiple patient use compared to a reference laboratory.

METHODS

The point-of-care international normalized ratio result of patients on oral anticoagulation at the Vascular Surgery clinic was compared to the reference to check for statistical and clinical correlation. This was a prospective case-control study design with sample size calculated for sensitivity of 87.5%, precision 5% and desired confidence level 95%.

RESULTS

There were 168 patients tested; 55% were male, the mean age was 45.4. Sixty per cent were in the target international normalized ratio range. Tests were done for statistical and clinical correlation. The international normalized ratio range using the point-of-care device was 0.8-7.5 (reference lab 0.8-10), mean international normalized ratio was 2.22 ± 1.6 (point-of-care device) compared to 2.46 ± 1.3 (reference lab). The mean absolute difference was 0.79 ± 0.92 and the mean relative difference was 8.1% ± 1.03. Data was analysed using a Bland-Altman plot yielding a mean of 0.738 (standard deviation 0.92). Concordance between the tests was 75% with r2 = 0.52 on linear regression. Using an error grid plot, excellent clinical correlation was seen in 63.8%. In 5.4% major corrective action was needed but potentially missed if relying on the point-of-care device.

CONCLUSION

The accuracy and precision of this point-of-care device is moderate. It may have potential utility only where access to a reference lab is difficult.

Reliability of a point-of-care device for international normalized ratio testing during the three surgical phases of orthotopic liver transplantation: a retrospective observational study

PURPOSE

To investigate the reliability of a point-of-care device, the HEMOCHRON(®) Jr. Signature, for measuring the international normalized ratio (INR) during the three surgical phases of liver transplantation.

METHODS

A retrospective review was performed on patients undergoing liver transplantation during July to December 2013. Thirty-one patients who had simultaneous laboratory and point-of-care INR readings from each phase of liver transplant surgery (paleohepatic, anhepatic, and neohepatic) were eligible for inclusion. Bland-Altman analysis, Spearman's rank correlation, and four quadrant plots were used to compare INR results from the point-of-care device (pocINR) with those from the laboratory (labINR).

RESULTS

Based on the Bland-Altman analysis, mean biases (95% prediction interval) were 0.10 (0.03 to 0.17), 0.19 (0.12 to 0.27), and 0.21 (0.01 to 0.43) for the paleohepatic, anhepatic, and neohepatic phases, respectively. The pocINR device showed a systematic underestimation of the labINR. The Spearman's rank correlation coefficients (95% confidence interval [CI]) were: Ρ = 0.90 (95% CI 0.80 to 0.95); Ρ = 0.92 (95% CI 0.71 to 0.93); and Ρ = 0.71 (95% CI 0.46 to 0.85), respectively. Direction-of-change analysis between the paleohepatic to anhepatic and the anhepatic to neohepatic phases showed strong concordance of 84% and, also considering the small bias between the measurements, supports the use of the pocINR device in the clinical management of liver transplant surgery.

CONCLUSION

Point-of-care INR was accurate prior to hepatic reperfusion, but reliability decreased in the neohepatic phase.

Home testing past, present and future: lessons learned and implications for HIV home tests

The recent approval in the United States of the first rapid home test to diagnose HIV raises questions about its potential use and impact. We reviewed the existing literature on the unassisted use of home tests involving self-collection and testing of biological samples by untrained users-including existing HIV self-testing studies-to shed some light on what can be expected from the availability of the HIV home test. The studies reviewed showed that most participants could properly perform home tests, obtain accurate results, and interpret them-yielding high correlations with laboratory and health-professional performed tests. Users often had trouble performing blood-based tests. Participants generally understood the need to confirm positive test results. Materials accompanying HIV home tests should emphasize symptoms of acute infection and the need for additional testing when recent infection is suspected. Different home-test-based screening modalities, personalized HIV-counseling resources and HIV home test impact evaluation methods should be studied.

The economic costs of routine INR monitoring in infants and children--examining point-of-care devices used within the home setting compared to traditional anticoagulation clinic monitoring

INTRODUCTION

The use of point-of-care (POC) devices within the home for routine INR monitoring has demonstrated reliability, safety and effectiveness in the management of infants and children requiring long-term warfarin therapy. However, a comprehensive cost-analysis of using this method of management, compared to attending anticoagulation clinics has not been reported. The aim of this study was to compare the estimated societal costs of attending anticoagulation clinics for routine INR monitoring to using a POC test in the home.

MATERIALS AND METHODS

This study used a comparative before-and-after design that included 60 infants and children managed via the Haematology department at a tertiary paediatric centre. Each participant was exposed to both modes of management at various times for a period of ≥3 months. A questionnaire, consisting of 25 questions was sent to families to complete and return. Data collected included: the frequency of monitoring, mode of travel to and from clinics, total time consumed, and primary carer's income level.

RESULTS

The home monitoring cohort saved a total of 1 hour 19 minutes per INR test compared to attending anticoagulation clinics and had a cost saving to society of $66.83 (AUD) per INR test compared to traditional care; incorporating health sector costs, travel expenses and lost time.

CONCLUSIONS

The traditional model of care requires a considerable investment of time per test from both child and carer. Home INR monitoring in infants and children provides greater societal economic benefits compared to traditional models.

Telemedicine improves the monitoring process in anticoagulant treatment

We compared the INR (International Normalized Ratio) monitoring process using a telemedicine device with the conventional approach in which blood samples were sent to the hospital for analysis. We conducted a randomized controlled trial. We enrolled 40 patients on chronic warfarin therapy from two primary healthcare centres (PHCs). Half were monitored using the telemedicine device and half were monitored conventionally. Each patient received three INR measurements. The total processing time was measured from blood sampling until warfarin dosing was performed in the anticoagulant clinic. The median total processing time was significantly shorter with telemedicine than usual care (34 vs. 260 min, P < 0.001). This was mainly because sample transport was avoided using the point-of-care device and automatic data transmission. Telemedicine reduced the total processing time for INR monitoring and has the potential to improve the management of patients undergoing anticoagulant treatment at PHCs.

Prospective comparison of point-of-care international normalised ratio measurement versus plasma international normalised ratio for acute traumatic coagulopathy

OBJECTIVE

Early detection of acute traumatic coagulopathy (ATC) might be useful to guide trauma resuscitation. This study aimed to compare results from a point-of-care (POC) international normalised ratio (INR) measuring device with plasma INR in acute trauma patients.

METHODS

This was a single-centre, prospective, blinded comparative study. All trauma patients meeting trauma call-out criteria in a major trauma centre were screened. Patients predicted to have ATC were identified by the Coagulopathy of Severe Trauma score and a convenience sample of 72 patients included in this study. Whole blood was used to measure INR at the bedside, whereas blood from the same sample was sent to the hospital laboratory for plasma INR testing. Agreement between the laboratory and bedside INR was determined using a Bland-Altman plot.

RESULTS

There were 38 (52.8%) patients with ATC by laboratory measure, defined as INR >1.5 or activated partial thrombin time >60 s, whereas the POC system identified 28 (38.9%) patients with an INR >1.5. Assuming the laboratory measure as the gold standard, the POC system had a specificity of 88.2% (95% confidence interval 71.6-96.2) and a sensitivity of 63.1% (95% confidence interval 46.0-77.7). Bland-Altman plots demonstrated inadequate agreement between the two methods of INR measurement for the major trauma patient.

CONCLUSIONS

POC INR measurements using this method during the trauma reception and resuscitative phases cannot be used to identify or exclude patients with ATC. Further studies are required to determine if there is any role for POC INR measures during trauma resuscitation.

A retrospective review of clinical international normalized ratio results and their implications

BACKGROUND

Warfarin is a key element in therapy for atrial fibrillation, deep venous thrombosis (DVT), stroke (cerebrovascular accident) and cardiac valve replacement. Often, patients' warfarin blood levels are not tightly controlled with regard to accepted therapeutic ranges, by virtue of the drug's unpredictable nature.

METHODS

The authors searched 16,017 active clinical charts for active patients of record from the three campuses of the School of Dentistry, Marquette University (MU), Milwaukee, for the years 2009 and 2010. Dental records of 315 patients contained entries including "INR," the abbreviation for the term "international normalized ratio." Only 247 of those records contained an indication of whether the patient's INR values were within therapeutic range. The authors found that 1.96 percent of the total MU dental clinic patient population had a history of warfarin use.

RESULTS

When the authors compared the INR values for patients with diagnoses of atrial fibrillation, DVT, stroke and cardiac valve replacement, they found that INR values for 107 of the 247 patients (43.3 percent) were not within therapeutic range for the respective diagnoses. For example, only 50 percent of the patients being treated for atrial fibrillation presented themselves for surgical dental treatment while their INR values were in tight control.

CONCLUSION

The INR values for a significant number of dental patients are not within the therapeutic range for their medical conditions. These patients need to seek follow-up care from their medical care providers.

CLINICAL IMPLICATIONS

Screening for INR in the dental office-especially before invasive dental treatment such as periodontal surgery, tooth extraction and dental implant placement-can help prevent postoperative complications. It also can aid the clinician in evaluating whether a patient's INR is within therapeutic range and, subsequently, whether the patient's physician needs to adjust the warfarin dosage.

Oral anticoagulant therapy: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines

BACKGROUND

The objective of this article is to summarize the published literature concerning the pharmacokinetics and pharmacodynamics of oral anticoagulant drugs that are currently available for clinical use and other aspects related to their management.

METHODS

We carried out a standard review of published articles focusing on the laboratory and clinical characteristics of the vitamin K antagonists; the direct thrombin inhibitor, dabigatran etexilate; and the direct factor Xa inhibitor, rivaroxaban

RESULTS

The antithrombotic effect of each oral anticoagulant drug, the interactions, and the monitoring of anticoagulation intensity are described in detail and discussed without providing specific recommendations. Moreover, we describe and discuss the clinical applications and optimal dosages of oral anticoagulant therapies, practical issues related to their initiation and monitoring, adverse events such as bleeding and other potential side effects, and available strategies for reversal.

CONCLUSIONS

There is a large amount of evidence on laboratory and clinical characteristics of vitamin K antagonists. A growing body of evidence is becoming available on the first new oral anticoagulant drugs available for clinical use, dabigatran and rivaroxaban.

Home management of oral anticoagulation via telemedicine versus conventional hospital-based treatment

BACKGROUND AND OBJECTIVE

We have developed an expert computer system for the control of oral anticoagulation therapy, accessible by the patients via their own computer. To investigate if the weekly measurement and dosing of international normalized ratio (INR) at home using the online Internet-based system was superior to conventional treatment, we performed a randomized, controlled trial.

PATIENTS AND METHODS

All 669 patients in our anticoagulation clinic were asked to participate in the trial, providing that they had Internet access and could use the CoaguChek XS system. A total of 140 patients were included and randomized to (A) once weekly measurement and report online, (B) twice weekly measurement and report online, and (C) continued conventional treatment with INR measurement in the lab every 4 weeks and dose adjustment by letter.

RESULTS

Group A had 79.7% (95% CI 79.0-80.3) of time in therapeutic range (TTR), group B 80.2% (95% CI 79.4-80.9) of TTR, and group C 72.7% (95% CI 71.9-73.4) TTR. Groups A and B perform statistically significantly better than the conventional group C, with a difference of TTR of 7% points (p < 2.2 × 10(-16)), whereas no difference was seen between A and B.

CONCLUSION

Home measurement of INR and the reporting and dosing of results online once a week increase TTR from 72% to 79% as compared to conventional computer-assisted monitoring in an anticoagulation clinic.

[Portable coagulometer devices in the monitoring and control of oral anticoagulation therapy: a systematic review]

OBJECTIVE

To compare portable coagulometer devices and conventional coagulometers. The clinical validity will be estimated via anticoagulation control (maintenance of therapeutic range), patient satisfaction, thrombotic or haemorrhagic events and mortality. Analytical validity will be studied in quality control terms.

DESIGN

Systematic review.

DATA SOURCES

MEDLINE and EMBASE databases, CRD, Cochrane, EMEA, FDA, EuroScan and the ClinicalTrials.gov.

METHODS

Inclusion criteria were studied in patients on anticoagulation therapy who used portable coagulometer devices. In an additional undertaking, the comparison with lab references was looked for, in order to evaluate the effectiveness. The quality of selected studies was assessed according to CASPe check-list. As meta-analysis was not possible, a qualitative synthesis was made.

RESULTS

Four evaluation reports and 7 systematic reviews were selected (two of them with meta-analysis). After these, 22 original articles were included for this review and they had high or very high score for CASPe check-list (≥7/10). Almost all of the studies found very high correlations between portable coagulometer devices and conventional coagulometers (r>90), and clinical advantages such as lower incidence of thromboembolism events. Three systematic reviews showed a lower mortality index.

CONCLUSIONS

The analytical-validity related articles show that portable coagulometers have an equivalent effectiveness to conventional coagulometers. Studies that include patient-reported outcomes show that self-monitoring patients, by means of portable coagulometers, have better analytical measurement results and fewer rates of thromboembolic events. Survival was analysed in very few studies; nevertheless, all of these show lower mortality. Similarly, the minority of selected articles includes economic evaluations, although they suggest a better cost-effectiveness of portable coagulometers compared to the conventional mode.

Characteristics of ambulatory anticoagulant adverse drug events: a descriptive study

BACKGROUND

Despite the high frequency with which adverse drug events (ADEs) occur in outpatient settings, detailed information regarding these events remains limited. Anticoagulant drugs are associated with increased safety concerns and are commonly involved in outpatient ADEs. We therefore sought to evaluate ambulatory anticoagulation ADEs and the patient population in which they occurred within the Duke University Health System (Durham, NC, USA).

METHODS

A retrospective chart review of ambulatory warfarin-related ADEs was conducted. An automated trigger surveillance system identified eligible events in ambulatory patients admitted with an International Normalized Ratio (INR) >3 and administration of vitamin K. Event and patient characteristics were evaluated, and quality/process improvement strategies for ambulatory anticoagulation management are described.

RESULTS

A total of 169 events in 167 patients were identified from December 1, 2006-June 30, 2008 and included in the study. A median supratherapeutic INR of 6.1 was noted, and roughly half of all events (52.1%) were associated with a bleed. Nearly 74% of events resulted in a need for fresh frozen plasma; 64.8% of bleeds were classified as major. A total of 59.2% of events were at least partially responsible for hospital admission. Median patient age was 68 y (range 36-95 y) with 24.9% initiating therapy within 3 months prior to the event. Of events with a prior documented patient visit (n = 157), 73.2% were seen at a Duke clinic or hospital within the previous month. Almost 80% of these patients had anticoagulation therapy addressed, but only 60.0% had a follow-up plan documented in the electronic note.

CONCLUSIONS

Ambulatory warfarin-related ADEs have significant patient and healthcare utilization consequences in the form of bleeding events and associated hospital admissions. Recommendations for improvement in anticoagulation management include use of information technology to assist monitoring and follow-up documentation, avoid drug interactions, and engage patients in their care.