Determination of the International Sensitivity Index of a New Near-Patient Testing Device to Monitor Oral Anticoagulant Therapy

1997 ◽  
Vol 78 (02) ◽  
pp. 855-858 ◽  
Author(s):  
Armando Tripodi ◽  
Veena Chantarangkul ◽  
Marigrazia Clerici ◽  
Barbara Negri ◽  
Pier Mannuccio Mannucci
Keyword(s):  
Linear Relationship ◽  
Whole Blood ◽  
Oral Anticoagulant ◽  
Oral Anticoagulant Therapy ◽  
Oral Anticoagulants ◽  
Calibration Model ◽  
Testing Device ◽  
Data Points ◽  
Near Patient Testing

SummaryA key issue for the reliable use of new devices for the laboratory control of oral anticoagulant therapy with the INR is their conformity to the calibration model. In the past, their adequacy has mostly been assessed empirically without reference to the calibration model and the use of International Reference Preparations (IRP) for thromboplastin. In this study we reviewed the requirements to be fulfilled and applied them to the calibration of a new near-patient testing device (TAS, Cardiovascular Diagnostics) which uses thromboplastin-containing test cards for determination of the INR. On each of 10 working days citrat- ed whole blood and plasma samples were obtained from 2 healthy subjects and 6 patients on oral anticoagulants. PT testing on whole blood and plasma was done with the TAS and parallel testing for plasma by the manual technique with the IRP CRM 149S. Conformity to the calibration model was judged satisfactory if the following requirements were met: (i) there was a linear relationship between paired log-PTs (TAS vs CRM 149S); (ii) the regression line drawn through patients data points, passed through those of normals; (iii) the precision of the calibration expressed as the CV of the slope was <3%. A good linear relationship was observed for calibration plots for plasma and whole blood (r = 0.98). Regression lines drawn through patients data points, passed through those of normals. The CVs of the slope were in both cases 2.2% and the ISIs were 0.965 and 1.000 for whole blood and plasma. In conclusion, our study shows that near-patient testing devices can be considered reliable tools to measure INR in patients on oral anticoagulants and provides guidelines for their evaluation.

Are Capillary Whole Blood Coagulation Monitors Suitable for the Control of Oral Anticoagulant Treatment by the International Normalized Ratio?

1993 ◽  
Vol 70 (06) ◽  
pp. 0921-0924 ◽  
Author(s):  
Armando Tripodi ◽  
Arnaldo A Arbini ◽  
Veena Chantarangkul ◽  
Donato Bettega ◽  
Pier Mannuccio Mannucci
Keyword(s):  
Whole Blood ◽  
Oral Anticoagulant ◽  
Oral Anticoagulant Therapy ◽  
Oral Anticoagulants ◽  
Regression Line ◽  
International Normalized Ratio ◽  
Rabbit Brain ◽  
Sensitivity Index ◽  
Calibration Model ◽  
Oral Anticoagulant Treatment

SummaryThe 512 Coagulation Monitor is a portable coagulation photometer that uses disposable cartridges containing a lyophilized rabbit brain thromboplastin to measure the PT for capillary whole blood. It has been proposed as a suitable system for patient self monitoring at home, but its performance has never been thoroughly assessed for results expressed as International Normalized Ratio (INR). In particular, there is no available information about the adequacy of the WHO calibration model with the Monitor. The aims of the study were to determine the International Sensitivity Index (ISI) against the secondary International Reference Preparation for rabbit thromboplastin and to assess the precision of the INR. The study demonstrates that the Monitor can be calibrated with the WHO model, because log-transformed PTs for patients stabilized on oral anticoagulants and normal individuals are linearly related and because the same orthogonal regression line describes patient and normal data points adequately. However, the ISI calculated in this study (2.715) is higher than that adopted by the manufacturer (2.036). The between-assay reproducibility of the Monitor is acceptable (CV = 9.7%) with results expressed in seconds, but become unacceptably poor when the results are converted into INR (CV = 18.8%) because of the high ISI value of the thromboplastin used. We think that the Monitor might be suitable for monitoring oral anticoagulant therapy if the manufacturer would provide a more sensitive thromboplastin in the cartridges.

scholarly journals Validation of Current Practice and a near Patient Testing Method for Oral-Anticoagulant Control in General Practice

1997 ◽  
Vol 90 (12) ◽  
pp. 657-660 ◽  
Author(s):  
David A Seamark ◽  
Susan Backhouse ◽  
Paul Barber ◽  
John Hichens ◽  
Richard Lee ◽  
...  
Keyword(s):  
General Practice ◽  
Whole Blood ◽  
Oral Anticoagulant ◽  
Control Method ◽  
Oral Anticoagulants ◽  
Maximum Temperature ◽  
Routine Method ◽  
Blood Samples ◽  
Acceptable Agreement ◽  
Near Patient Testing

When oral anticoagulant control is monitored in general practice, venous blood samples are usually transported to a central laboratory for determination of international normalized ratio (INR). An alternative is near patient testing by a commercial method. In a rural general practice 27 km from a central haematology laboratory, whole blood samples were drawn from patients receiving oral anticoagulants and analysed by three methods: after centrifugation, plasma separated and frozen in liquid nitrogen, transported to the laboratory, thawed and immediately analysed (control); courier transport of citrated sample to the laboratory for analysis (routine); near patient testing of whole blood sample (NPT). Maximum temperature achieved and time to analysis for routine samples were recorded. 306 complete sets of data were obtained. Comparison between the routine method and the control method revealed acceptable agreement. On multiple regression analysis, maximum temperature achieved did not contribute to differences observed but time to analysis of over 5 hours did make a significant contribution. Comparison between the NPT method and control method showed acceptable agreement, with persistent under-recording by the NPT method. The routine method for INR determination was validated as robust and reproducible with the proviso that needle-to-analysis time should be kept below 5 hours. The NPT method was valid under conditions of normal general practice. Strict quality control of NPT methods is essential if performance is to be comparable with that of established methods.

scholarly journals Educational protocol for patients on oral anticoagulant therapy: construction and validation

2014 ◽  
Vol 23 (3) ◽  
pp. 799-806 ◽  
Author(s):  
Flávia Martinelli Pelegrino ◽  
Fabiana Bolela ◽  
Inaiara Scalçone de Almeida Corbi ◽  
Ariana Rodrigues da Silva Carvalho ◽  
Rosana Aparecida Spadoti Dantas
Keyword(s):  
Literature Review ◽  
Oral Anticoagulant ◽  
Social Cognitive ◽  
Cognitive Theory ◽  
Oral Anticoagulant Therapy ◽  
Oral Anticoagulants ◽  
Anticoagulation Therapy ◽  
Oral Anticoagulation Therapy ◽  
Final Version ◽  
The Face

This is a report of experience on the construction and validation of an educational protocol for patients on oral anticoagulation therapy. Based on Bandura's Social Cognitive Theory, three phases were identified to construct the educational protocol. The literature review on oral anticoagulants was used to prepare the content of each phase of the protocol. As a result, verbal and written orientation in the phases of attention and retention were developed. In the reproduction and motivation phase, support through contact by telephone was provided. And finally, an improvement in the evaluation of the outcomes related to oral anticoagulant is expected in the performance phase. Once the educational protocol was defined, we proceeded with the face and content validity process, which allowed adaptations to the final version of the educational protocol constructed.

scholarly journals HAS-BLED scor system for the assessment of risk of breathing of patients on oral anticoagulant therapy // HAS-BLED skor sistem bodovanja za procjenu rizika od krvarenja pacijenata na oralnoj antikoagulantnoj terapiji

2018 ◽  
Vol 5 (1) ◽  
pp. 11
Author(s):  
Daniela Dobrovoljski
Keyword(s):  
Atrial Fibrillation ◽  
Oral Anticoagulant ◽  
Oral Anticoagulant Therapy ◽  
Vitamin K Antagonists ◽  
Oral Anticoagulants ◽  
Heart Rhythm ◽  
Clinical Problem ◽  
Coagulation Factors ◽  
Heart Rhythm Disorders ◽  
Anticoagulant Drugs

Oral anticoagulant drugs (OALs) are effective agents in the prevention and treatment of thromboembolic complications. However, despite standardization and application progression, OALs represent a significant clinical problem because they are small-therapeutic medicines that easily interact with food and medicine, which can substantially affect the increased or weakened therapeutic effect. Oral anticoagulants are 4-hydroxycoumarin derivatives and vitamin K antagonists, and their pharmacological activity is based on inhibition of the synthesis of coagulation factors in the liver. These drugs are effective in the prevention of venous thromboembolism, acute myocardial infarction (AIM), heart rhythm disorders by type of atrial fibrillation, stroke prevention, and the like. The most important and clinically commonly undesirable effect of OAL is bleeding. The risk of bleeding is greatest during the introduction of the drug in therapy and for the first few months of the onset of therapy. HAS-BLED scor is a skoring system developed to estimate the 1-year risk of major bleeding in patients with atrial fibrillation and is also used for other indications.

Results of a Multicenter Study Assessing the Status of Standardization of a Recombinant Thromboplastin for the Control of Oral Anticoagulant Therapy

1994 ◽  
Vol 72 (02) ◽  
pp. 261-267 ◽  
Author(s):  
A Tripodi ◽  
V Chantarangkul ◽  
M Braga ◽  
L poller ◽  
J W ten Cate ◽  
...  
Keyword(s):  
Statistical Analysis ◽  
Oral Anticoagulant Therapy ◽  
Oral Anticoagulants ◽  
Collaborative Study ◽  
The Third ◽  
Normal Individuals ◽  
The Status ◽  
Data Points ◽  
Relationship Of ◽  
International Collaborative Study

SummaryAn international collaborative study involving 20 laboratories was undertaken to evaluate the status of standardization of a commerical recombinant thromboplastin. The results show that the reagent fulfills the WHO requirements for thromboplastin calibration against two International Reference Preparations (IRP) from different species, because there was a linear relationship of log-transformed prothrombin times as measured by the recombinant reagent and the two IRPs in normal individuals and patients stabilized on oral anticoagulants. The regression lines drawn through the patient data points passed through the normal data points in the majority of instances. The average ISI values for three different batches were close to unity. On the average, the ISI value calculated against BCT/253 (human, plain) was slightly smaller than that against RBT/79 (rabbit, plain). The between laboratory precision of calibration (CV = 5-6%) did not change whether BCT/253 or RBT/79 was used, whereas it was substantially improved when the calibrations of batches 2 and 3 were performed against batch 1, arbitrarily taken as standard (CV ≤ 1.7%). Statistical analysis to test for differences between slopes revealed no significant between-batch differences in 16 of 20 laboratories. However slight differences for the third batch (2.8% less than the average ISI value of batches 1 and 2) leave room for further improvement in the standardization of the reagent.

Rebound Phenomenon After Discontinuation Of Oral Anticoagulant Therapy?

1981 ◽  
Author(s):  
J Harenberg ◽  
R Haas ◽  
R Zimmermann
Keyword(s):  
Anticoagulant Therapy ◽  
Oral Anticoagulant ◽  
Oral Anticoagulant Therapy ◽  
Oral Anticoagulants ◽  
Anticoagulation Therapy ◽  
In Vitro Release ◽  
Oral Anticoagulant Treatment ◽  
Thrombin Activity ◽  
Rebound Phenomenon

Duration and discontinuation of oral anticoagulant therapy in the prophylaxis of recurrent thrombembolic diseases is often discussed. After stopping of the therapy an elevated incidence of rethromboses are observed. Therefore we determined fibrinopeptide A (FPA) as the most sensitive parameter of thrombin activity in vivo in patients treated with phenprocoumon in order to get information on the effectivity of the oral anticoagulant therapy and on the rebound phenomenon after discontinuation of the treatment.In 136 outpatients a significant relation between FPA and the effectivity of the anticoagulant therapy was observed: 2.7 ng/ml plasma (mean, thrombotest values < 5%), 3.5 ng/ml (5%-15%) and 4.1 ng/ml (>15%, p < 0.01). Normal FPA were 1.4ng/ml. In 11 patients with low FPA the oral anticoagulants were discontinued. FPA was determined in weekly intervalls. Within four weeks a continous increase of FPA from 1.6 ng/ml (median) to 3.8 ng/ml was observed. After eight weeks FPA was 8.2 ng/ ml (p < 0.05). The in vitro release of FPA after 10 min incubation of blood increased from 3.4ng/ml to 72 ng/ml after eight weeks (p < 0.05, normal release up to 5 ng/ml).The data indicate the clinical relevance and the different therapeutic implications of the determination of FPA in patients treated with phenprocoumon. They further give the first criterion, which outlines the effectivity of an oral anticoagulation therapy by reducing the thrombin activity in vivo. They give some evidence for a rebound like phenomenon after discontinuation of the oral anticoagulant treatment.

scholarly journals Are Patients on Oral Anticoagulation Therapy Aware of its Effects? A Cross-sectional Study from Karachi, Pakistan

2020 ◽  
Author(s):  
Ibrahim Zahid ◽  
Syed Wajih Ul Hassan ◽  
Nida Sehar Bhurya ◽  
Sheena Nadeem Alam ◽  
Bakht Hussain Shah ◽  
...  
Keyword(s):  
Side Effects ◽  
Anticoagulant Therapy ◽  
Oral Anticoagulant ◽  
Oral Anticoagulant Therapy ◽  
Oral Anticoagulants ◽  
Anticoagulation Therapy ◽  
Herbal Medicines ◽  
Cross Sectional Study ◽  
Cross Sectional ◽  
Life Threatening

Abstract Objective: Oral anticoagulants are one of the most frequently used medications. However, these drugs have a range of side effects including potential life-threatening complications. Little is known regarding the awareness of its side effect profile amongst the patients in Pakistan. Therefore, the aim of this study was to assess the knowledge of oral anticoagulant therapy and its side effects among its users. Results: The mean age was 48.9 ± 15.2 years. Mean scores of the participants for knowledge regarding oral anticoagulants and knowledge specific to warfarin were 49.9 ± 16.2% and 14.6 ± 16.4% respectively. Most notably, the majority of the patients (65.7%) did not know what side effects to be wary of or how to reduce their occurrence; and most of them were unaware of the interaction between oral anticoagulant drugs and over-the-counter substances such as aspirin, herbal medicines and alcohol. Knowledge of International Normalised Ratio (INR) was extremely poor with more than 75% of the population not being aware of the target INR range during warfarin therapy. Higher level of education was significantly associated with better knowledge scores. On the whole, knowledge of oral anticoagulant therapy and INR monitoring is extremely poor among oral anticoagulant users.

Utility of a Modified Calibration Model for Reliable Conversion of Thromboplastin Times to International Normalized Ratios

1986 ◽  
Vol 56 (02) ◽  
pp. 178-182 ◽  
Author(s):  
G O Gogstad ◽  
J Wadt ◽  
P Smith ◽  
T Brynildsrud
Keyword(s):  
Anticoagulant Therapy ◽  
Coefficient Of Variation ◽  
Calculation Method ◽  
Oral Anticoagulant ◽  
Oral Anticoagulant Therapy ◽  
Calibration Model ◽  
Calibration Line ◽  
Modified Model ◽  
Reference Preparation ◽  
The Mean

SummaryThe combined thromboplastin reagent, Normotest, has been calibrated against the secondary international reference preparation for bovine thromboplastin, OBT/79. Three expert laboratories measured up to 62 patients on stabilized oral anticoagulant therapy and up to 20 normals in order to establish an INR-scale for Normotest. It was found that the model recommended by the WHO was less suited for the calibration of this thromboplastin. This is the first study in which three independent laboratories demonstrate a similar bias of the WHO calibration model. A modified model in which a correction factor is introduced was applied to the problem and proved to give a reliable calculation method for INR on Normotest. The mean coefficient of variation of INR calculated between measurements with Normotest and OBT/79 (scatter of data around calibration line) was 4.2-5.0% as compared to 5.1-5.7% for the WHO-method. A conversion scale for percent activities between Normotest and Thrombotest was established showing that the recommended therapeutic range of 5-10% Thrombotest (INR = 4.8-2.8) corresponds to 10-20% Normotest.

scholarly journals New Cancer Diagnosis After Bleeding in Anticoagulated Patients With Atrial Fibrillation

2020 ◽  
Vol 9 (22) ◽  
Author(s):  
Sergio Raposeiras Roubín ◽  
Emad Abu Assi ◽  
Cristina Barreiro Pardal ◽  
María Cespón Fernandez ◽  
Isabel Muñoz Pousa ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Anticoagulant Therapy ◽  
Cancer Diagnosis ◽  
Oral Anticoagulant ◽  
Oral Anticoagulant Therapy ◽  
Oral Anticoagulants ◽  
Bleeding Events ◽  
Using Data ◽  
Anticoagulated Patients

Background Bleeding is frequent in patients with atrial fibrillation (AF) treated with oral anticoagulant therapy, and may be the first manifestation of underlying cancer. We sought to investigate to what extent bleeding represents the unmasking of an occult cancer in patients with AF treated with oral anticoagulants. Methods and Results Using data from CardioCHUVI‐AF (Retrospective Observational Registry of Patients With Atrial Fibrillation From Vigo's Health Area), 8753 patients with AF aged ≥75 years with a diagnosis of AF between 2014 and 2017 were analyzed. Of them, 2171 (24.8%) experienced any clinically relevant bleeding, and 479 (5.5%) were diagnosed with cancer during a follow‐up of 3 years. Among 2171 patients who experienced bleeding, 198 (9.1%) were subsequently diagnosed with cancer. Patients with bleeding have a 3‐fold higher hazard of being subsequently diagnosed with new cancer compared with those without bleeding (4.7 versus 1.4 per 100 patient‐years; adjusted hazard ratio [HR], 3.2 [95% CI, 2.6–3.9]). Gastrointestinal bleeding was associated with a 13‐fold higher hazard of new gastrointestinal cancer diagnosis (HR, 13.4; 95% CI, 9.1–19.8); genitourinary bleeding was associated with an 18‐fold higher hazard of new genitourinary cancer diagnosis (HR, 18.1; 95% CI, 12.5–26.2); and bronchopulmonary bleeding was associated with a 15‐fold higher hazard of new bronchopulmonary cancer diagnosis (HR, 15.8; 95% CI, 6.0–41.3). For other bleeding (nongastrointestinal, nongenitourinary, nonbronchopulmonary), the HR for cancer was 2.3 (95% CI, 1.5–3.6). Conclusions In patients with AF treated with oral anticoagulant therapy, any gastrointestinal, genitourinary, or bronchopulmonary bleeding was associated with higher rates of new cancer diagnosis. These bleeding events should prompt investigation for cancers at those sites.

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