COMPARISON OF INTERNATIONAL NORMALIZED RATIO (INR) BETWEEN POINT OF CARE DEVICE COAGUCHEK® XS VERSUS STANDARD LABORATORY INSTRUMENT AMONG PATIENTS RECEIVING WARFARIN THERAPY IN A NORTHEAST STATE OF PENINSULAR MALAYSIA

Abstract Point of care (POC) testing of International Normalized Ratio (INR) for monitoring warfarin therapy is rapidly becoming procedure of choice for patients requiring long term oral anticoagulation. This method allows for fingerstick blood sample to be used for INR testing at the point of service with immediate dose modification as needed. Most patients prefer a fingerstick method for blood draw to venipuncture. It is not known if venipuncture blood sample can be used for testing on POC machines. A significant number of patients in an oncology practice need additional laboratory testing on the same day as INR testing. These patients therefore get a fingerstick for POC INR testing and a venipuncture for other tests. We compared results of INR from venipuncture sample run on a POC machine (CoaguChek monitor) using CoaguChek test strips (ISI-2.0) with the INR performed on MDA analyzer (ISI-2.0). Blood samples from 24 patients on warfarin therapy were drawn from antecubital vein by a clean stick in a 10 cc plastic syringe. A drop of blood was immediately placed on the CoaguCheck test strip. Next the same blood sample was used to fill a 3.2% sodium citrate tube for testing on MDA analyzer. Results were analyzed using regression analysis; the correlation coefficient (r), slope and intercept were determined and following graph of the regression analysis was generated (see figure 1). Conclusions: These results show a good correlation (r-value> 0.9) between the results of INR obtained on CoaguChek POC machine and the MDA analyzer using venipuncture blood sample. The preferred method to obtain blood sample for POC INR monitoring must remain fingerstick sample as per manufacturer’s recommendations. However, for those patients who need more than one blood sample done on the same day, a venipuncture sample as described above gives acceptable results when tested on CoaguCheck machine. Figure Figure

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Accuracy of the CoaguChek XS for point-of-care international normalized ratio (INR) measurement in children requiring warfarin

Thrombosis and Haemostasis ◽

10.1160/th07-10-0634 ◽

2008 ◽

Vol 99 (06) ◽

pp. 1097-1103 ◽

Cited By ~ 45

Author(s):

Karina Black ◽

Mary Massicotte ◽

Michelle Bauman ◽

Stefan Kuhle ◽

Susan Howlett-Clyne ◽

...

Keyword(s):

Point Of Care ◽

Vitamin K Antagonists ◽

Venous Blood ◽

International Normalized Ratio ◽

Test Results ◽

Standard Laboratory ◽

Limits Of Agreement ◽

Time Points ◽

Coaguchek Xs ◽

Roche Diagnostics

SummaryPoint-of-care INR (POC INR) meters can provide a safe and effective method for monitoring oral vitamin K antagonists (VKAs) in children. Stollery Children’s Hospital has a large POC INR meter loan program for children requiring oral VKAs. Our protocol requires that POC INR results be compared to the standard laboratory INR for each child on several consecutive tests to ensure accuracy of CoaguChek XS® (Roche Diagnostics, Basel Switzerland) meter. It was the objective of the study to determine the accuracy of the CoaguChek XS by comparing whole blood INR results from the CoaguChek XS to plasma INR results from the standard laboratory in children. POC INR meter validations were performed on plasma samples from two time points from 62 children receiving warfarin by drawing a venous blood sample for laboratory prothrombin (PT)-INR measurements and simultaneous INR determinations using the POC-INR meter. Agreement between CoaguChek XS INR and laboratory INR was assessed using Bland-Altman plots. Bland-Altman's 95% limits of agreement were 0.11 (-0.20; 0.42) and 0.13 (-0.22; 0.48) at the two time points, respectively. In conclusion, the CoaguChek XS meter appraisal generates an accurate and precise INR measure in children when compared to laboratory INR test results.

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Accuracy of the AvoSure PT Pro System Compared with a Hospital Laboratory Standard

Annals of Pharmacotherapy ◽

10.1345/aph.1a253 ◽

2002 ◽

Vol 36 (3) ◽

pp. 380-385 ◽

Cited By ~ 5

Author(s):

Janene M Rigelsky ◽

Hae Mi Choe ◽

Dawn M Curtis ◽

Marcia J Brosnan ◽

Sonya Mitrovich ◽

...

Keyword(s):

Prediction Error ◽

Point Of Care ◽

International Normalized Ratio ◽

Laboratory Method ◽

Standard Laboratory ◽

Altman Analysis ◽

Bland Altman Analysis ◽

Hospital Laboratory ◽

Squared Prediction Error ◽

Clinical Accuracy

OBJECTIVE: To compare international normalized ratio (INR) values obtained using the AvoSure PT Pro point-of-care (POC) system with those obtained using a standard laboratory method. METHODS: Forty-one INR values obtained from the POC system were compared with those obtained from a standard laboratory method. The POC method was evaluated for both laboratory and clinical agreement. To evaluate laboratory agreement, various analyses were used, including mean-squared prediction error (MSE) and mean prediction error (ME), Bland—Altman analysis, correlation, and paired t-test comparing group INR means. For clinical accuracy, discrepant pairs were identified and evaluated to determine whether dosage adjustments would have been needed based on values obtained. RESULTS: The POC system demonstrated modest precision (MSE = 0.147, 95% CI 0.065 to 0.228) and relatively little bias (ME = 0.090, 95% CI–0.025 to 0.205). Bland—Altman analysis also suggested good agreement at average INRs from 2.0 to 3.0. At average INR values >3.0, the POC system consistently overestimated INR. Values obtained with the POC system were significantly correlated with those obtained from the hospital laboratory (r = 0.77; p < 0.001). Similarly, mean ± SD POC INR did not differ significantly from the laboratory-determined INR (2.45 ± 0.59 vs. 2.37 ± 0.48, respectively; p = 0.176). Regarding clinical accuracy, the values clinically agreed in 85.4% of the cases. CONCLUSIONS: The AvoSure PT Pro POC system appears to be useful for INR values within the 2.0–3.0 range, but values outside of this range should probably be confirmed with a standard laboratory method.

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INR Management of an Antiphospholipid Syndrome Patient With Point-of-Care INR Testing

Journal of Pharmacy Practice ◽

10.1177/0897190019838192 ◽

2019 ◽

Vol 33 (3) ◽

pp. 390-391

Author(s):

Aaron Dush ◽

H. Paige Erdeljac

Keyword(s):

Antiphospholipid Syndrome ◽

Warfarin Therapy ◽

Point Of Care ◽

International Normalized Ratio ◽

Antiphospholipid Antibody ◽

Factor X ◽

Syndrome Patient

Management of patients with antiphospholipid syndrome on warfarin therapy can be challenging. The international normalized ratio (INR) of patients with antiphospholipid syndrome can be falsely elevated. This elevation is thought to be reflective of the reaction of the antiphospholipid antibody with the thromboplastin used to measure the protime. This false elevation can be seen in both venipuncture and point-of-care results. This discrepancy is usually more apparent in patients with whose INR is tested using point of care. As a result, there is a preference for venipuncture INR testing in most patients with antiphospholipid syndrome requiring warfarin therapy. In our case, we highlight one patient who we correlated her venipuncture INR with point-of-care INR as well as a chromogenic factor X level in order to manage her INR by point-of-care INR testing.

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Effect of coagulation factors on discrepancies in International Normalized Ratio results between instruments

Clinical Chemistry and Laboratory Medicine (CCLM) ◽

10.1515/cclm-2011-0820 ◽

2012 ◽

Vol 50 (9) ◽

Cited By ~ 8

Author(s):

Una Ørvim Sølvik ◽

Thomas Helge Røraas ◽

Per Hyltoft Petersen ◽

Anne Vegard Stavelin ◽

Grete Monsen ◽

...

Keyword(s):

Point Of Care ◽

Coagulation Factors ◽

International Normalized Ratio ◽

Systematic Difference ◽

Laboratory Measurements ◽

Blood Samples ◽

Laboratory Instrument ◽

Warfarin Treatment ◽

The Difference ◽

Different Levels

AbstractThe reasons for discrepancies between International Normalized Ratio (INR) results determined by point-of-care-instruments and laboratory measurements are not fully understood. In this study we investigated whether different levels of coagulation factors in the plasma of patients can explain some of the systematic and/or random parts of the difference in INR between the instruments.Blood samples were collected at four different patient visits from each of 34 outpatients on warfarin treatment. INR was determined on a laboratory instrument (STA CompactThe coagulation factors, especially fibrinogen, factors II and VII, could explain between 16% and 45% of the total variance of the differences in INR between instruments dependent on instruments compared. After correction for factors no systematic difference was seen for four of the six comparisons and the between- and within-subject variation of the differences were reduced by up to 69% and 52%, respectively.By correcting for the appropriate coagulation factors, especially the systematic differences, but also the between- and within-subject variation of the differences between instruments, were reduced. This indicates that different levels of coagulation factors in the plasma of the patients play an important role in explaining discrepancies between INR instruments.

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Prediction of the international normalized ratio and maintenance dose during the initiation of warfarin therapy

British Journal of Clinical Pharmacology ◽

10.1046/j.1365-2125.1999.00967.x ◽

1999 ◽

Vol 48 (1) ◽

pp. 63-70 ◽

Cited By ~ 11

Author(s):

Vadher ◽

Patterson ◽

Leaning

Keyword(s):

Maintenance Dose ◽

Warfarin Therapy ◽

International Normalized Ratio

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Concurrent Spontaneous Sublingual and Intramural Small Bowel Hematoma due to Warfarin Use

Case Reports in Emergency Medicine ◽

10.1155/2015/583869 ◽

2015 ◽

Vol 2015 ◽

pp. 1-3 ◽

Cited By ~ 1

Author(s):

Gül Pamukçu Günaydın ◽

Hatice Duygu Çiftçi Sivri ◽

Serkan Sivri ◽

Yavuz Otal ◽

Ayhan Özhasenekler ◽

...

Keyword(s):

Emergency Department ◽

Small Bowel ◽

Warfarin Therapy ◽

International Normalized Ratio ◽

Fresh Frozen Plasma ◽

Close Monitoring ◽

Observation Unit ◽

Fresh Frozen ◽

Tomography Scan ◽

Frozen Plasma

Introduction. We present a case of concurrent spontaneous sublingual and intramural small bowel hematoma due to warfarin anticoagulation.Case. A 71-year-old man presented to the emergency department complaining of a swollen, painful tongue. He was on warfarin therapy. Physical examination revealed sublingual hematoma. His international normalized ratio was 11.9. The computed tomography scan of the neck demonstrated sublingual hematoma. He was admitted to emergency department observation unit, monitored closely; anticoagulation was reversed with fresh frozen plasma and vitamin K. 26 hours after his arrival to the emergency department, his abdominal pain and melena started. His abdomen tomography demonstrated intestinal submucosal hemorrhage in the ileum. He was admitted to surgical floor, monitored closely, and discharged on day 4.Conclusion. Since the patient did not have airway compromise holding anticoagulant, reversing anticoagulation, close monitoring and observation were enough for management of both sublingual and spontaneous intramural small bowel hematoma.

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Impact of CYP2C9 and VKORC1 Polymorphisms on Warfarin Sensitivity and Responsiveness in Jordanian Cardiovascular Patients during the Initiation Therapy

Genes ◽

10.3390/genes9120578 ◽

2018 ◽

Vol 9 (12) ◽

pp. 578 ◽

Cited By ~ 10

Author(s):

Laith AL-Eitan ◽

Ayah Almasri ◽

Rame Khasawneh

Keyword(s):

Warfarin Therapy ◽

Catalytic Properties ◽

Warfarin Dose ◽

International Normalized Ratio ◽

Nucleotide Polymorphisms ◽

Single Nucleotide ◽

Haplotype Blocks ◽

Cardiovascular Patients ◽

Cyp2c9 Gene ◽

Vkorc1 Gene

Warfarin is an oral anticoagulant frequently used in the treatment of different cardiovascular diseases. Genetic polymorphisms in the CYP2C9 and VKORC1 genes have produced variants with altered catalytic properties. A total of 212 cardiovascular patients were genotyped for 17 Single Nucleotide Polymorphisms (SNPs) within the CYP2C9 and VKORC1 genes. This study confirmed a genetic association of the CYP2C9*3 and VKORC1 rs10871454, rs8050894, rs9934438, and rs17708472 SNPs with warfarin sensitivity. This study also found an association between CYP2C9 and VKORC1 genetic haplotype blocks and warfarin sensitivity. The initial warfarin dose was significantly related to the CYP2C9*3 polymorphism and the four VKORC1 SNPs (p < 0.001). There were significant associations between rs4086116 SNP and TAT haplotype within CYP2C9 gene and rs17708472 SNP and CCGG haplotype within VKORC1 gene and warfarin responsiveness. However, possessing a VKORC1 variant allele was found to affect the international normalized ratio (INR) outcomes during initiation of warfarin therapy. In contrast, there was a loose association between the CYP2C9 variant and INR measurements. These findings can enhance the current understanding of the great variability in response to warfarin treatment in Arabs.

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Fenofibrate Potentiates Warfarin Effects

Annals of Pharmacotherapy ◽

10.1177/106002800303700210 ◽

2003 ◽

Vol 37 (2) ◽

pp. 212-215 ◽

Cited By ~ 9

Author(s):

Karissa Y Kim ◽

Michael A Mancano

Keyword(s):

White Woman ◽

Chart Review ◽

Warfarin Therapy ◽

Dosage Reduction ◽

International Normalized Ratio ◽

Drug Regimen ◽

Warfarin Dosage ◽

Therapeutic Doses ◽

Anticoagulant Response

OBJECTIVE: To describe 2 patients in whom the initiation of fenofibrate potentiated warfarin's anticoagulant effects. CASE SUMMARY: A 71-year-old white woman and an 80-year-old white woman with multiple medical conditions were both stabilized on long-term warfarin therapy. During the course of anticoagulation, both patients were prescribed fenofibrate and experienced threefold and twofold increases in international normalized ratio (INR), respectively, requiring total weekly warfarin dosage reductions of 30–40%. Before starting fenofibrate therapy, both patients' coagulation values were within the therapeutic range. When interviewed, patients and caregivers denied bleeding, bruising, changes in diet, alcohol ingestion, nonadherence with therapy, or changes in drug regimen except for the addition of fenofibrate. Upon chart review, evaluation of potentially contributory parameters, such as other changes in drug therapy, thyroid function, liver function, and drug–disease interactions, showed that these parameters remained stable and were ruled noncontributory. DISCUSSION: The addition of fenofibrate in 2 patients on stable and therapeutic doses of warfarin increased the anticoagulant response to warfarin. A clear temporal relationship with the addition of fenofibrate and the appearance of the interaction was seen. Fenofibrate is highly protein bound, with the potential to displace warfarin from its binding protein, leading to an enhanced hypoprothrombinemic effect. Fenofibrate is also a mild to moderate inhibitor of CYP2C9, the enzyme responsible for warfarin metabolism. The combination of these effects — displacement of warfarin by fenofibrate coupled with decreased metabolism of warfarin — may increase the anticoagulant response to warfarin. Using the Naranjo probability scale, these interactions were designated as probable. CONCLUSIONS: We suggest serial monitoring of INR and consider an empiric 20% reduction in warfarin dosage when fenofibrate is initiated, with the possibility for a greater warfarin dosage reduction based on INR results.

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