scholarly journals Preanalytical Variables and Off-Site Blood Collection: Influences on the Results of the Prothrombin Time/International Normalized Ratio Test and Implications for Monitoring of Oral Anticoagulant Therapy

2005 ◽  
Vol 51 (3) ◽  
pp. 561-568 ◽  
Author(s):  
Johanna HH van Geest-Daalderop ◽  
André B Mulder ◽  
Leandra JM Boonman-de Winter ◽  
Martha MCL Hoekstra ◽  
Anton MHP van den Besselaar
Keyword(s):  
Prothrombin Time ◽  
Anticoagulant Therapy ◽  
Oral Anticoagulant ◽  
Room Temperature ◽  
Oral Anticoagulant Therapy ◽  
International Normalized Ratio ◽  
Blood Collection ◽  
Ratio Test ◽  
Mechanical Agitation ◽  
The Impact

Abstract Background: The quality of oral anticoagulant therapy management with coumarin derivatives requires reliable results for the prothrombin time/International Normalized Ratio (PT/INR). We assessed the effect on PT/INR of preanalytical variables, including ones related to off-site blood collection and transportation to a laboratory. Methods: Four laboratories with different combinations of blood collection systems, thromboplastin reagents, and coagulation meters participated. The simulated preanalytical variables included time between blood collection and PT/INR determinations on samples stored at room temperature, at 4–6 °C, and at 37 °C; mechanical agitation at room temperature, at 4–6 °C, and at 37 °C; time between centrifugation and PT/INR determination; and times and temperatures of centrifugation. For variables that affected results, the effect of the variable was classified as moderate when <25% of samples showed a change >10% or as large if >25% of samples showed such a change. Results: During the first 6 h after blood collection, INR changed by >10% in <25% of samples (moderate effect) when blood samples were stored at room temperature, 4–6 °C, or 37 °C with or without mechanical agitation and independent of the time of centrifugation after blood collection. With one combination of materials and preanalytical conditions, a 24-h delay at room temperature or 4–6 °C had a large effect, i.e., changes >10% in >25% of samples. In all laboratories, a 24-h delay at 37 °C or with mechanical agitation had a large effect. We observed no clinically or statistically relevant INR differences among studied centrifugation conditions (centrifugation temperature, 20 °C or no temperature control; centrifugation time, 5 or 10 min). Conclusions: We recommend a maximum of 6 h between blood collection and PT/INR determination. The impact of a 24-h delay should be investigated for each combination of materials and conditions.

Relationship Between Total Prothrombin, Native Prothrombin and the International Normalized Ratio (INR)

1992 ◽  
Vol 68 (02) ◽  
pp. 160-164 ◽  
Author(s):  
P J Braun ◽  
K M Szewczyk
Keyword(s):  
Anticoagulant Therapy ◽  
Oral Anticoagulant ◽  
Inverse Relationship ◽  
Low Dose ◽  
Oral Anticoagulant Therapy ◽  
International Normalized Ratio ◽  
Antigen Assay ◽  
Dose Oral ◽  
Anticoagulated Patients ◽  
Sensitive Method

SummaryPlasma levels of total prothrombin and fully-carboxylated (native) prothrombin were compared with results of prothrombin time (PT) assays for patients undergoing oral anticoagulant therapy. Mean concentrations of total and native prothrombin in non-anticoagulated patients were 119 ± 13 µg/ml and 118 ± 22 µg/ml, respectively. In anticoagulated patients, INR values ranged as high as 9, and levels of total prothrombin and native prothrombin decreased with increasing INR to minimum values of 40 µg/ml and 5 µg/ml, respectively. Des-carboxy-prothrombin increased with INR, to a maximum of 60 µg/ml. The strongest correlation was observed between native prothrombin and the reciprocal of the INR (1/INR) (r = 0.89, slope = 122 µg/ml, n = 200). These results indicated that native prothrombin varied over a wider range and was more closely related to INR values than either total or des-carboxy-prothrombin. Levels of native prothrombin were decreased 2-fold from normal levels at INR = 2, indicating that the native prothrombin antigen assay may be a sensitive method for monitoring low-dose oral anticoagulant therapy. The inverse relationship between concentration of native prothrombin and INR may help in identification of appropriate therapeutic ranges for oral anticoagulant therapy.

scholarly journals Impact of care coordination on oral anticoagulant therapy among patients with atrial fibrillation in routine clinical practice in Japan: a prospective, observational study

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Fumiko Ono ◽  
◽  
Sayako Akiyama ◽  
Akifumi Suzuki ◽  
Yoshinobu Ikeda ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Anticoagulant Therapy ◽  
Care Coordination ◽  
Oral Anticoagulant ◽  
Oral Anticoagulant Therapy ◽  
Critical Issue ◽  
Newly Diagnosed ◽  
Clinical Practices ◽  
Patient Reported ◽  
The Impact

Abstract Background Care coordination between general practitioners (GPs) and cardiovascular specialists is expected to play a key role in establishing appropriate oral anticoagulant (OAC) treatment in atrial fibrillation (AF) patients. The aim of this study was to assess the impact of care coordination on oral anticoagulant therapy in the management of AF in Japan. Methods This study was a multi-center, single-arm, prospective cohort study with retrospective chart and claims data review for historical controls. The study included three study periods: a 12-month pre-campaign period; a 12-month campaign period for AF screening and care coordination; and a 3-month post-campaign period for follow-up of care coordination. During the campaign period, patients aged ≥65 years who attended participating GP clinics underwent opportunistic AF screening by GPs under the campaign. At the discretion of the GP, newly diagnosed AF patients after the screening were referred to a cardiovascular specialist for care coordination. To assess the impact of care coordination and evaluate the effects of the campaign, implementation of care coordination, antithrombotic therapies, and patient-reported outcomes were compared between patients with and without care coordination, and between patients during the pre-campaign and campaign periods. Results There were 86 newly diagnosed AF patients during the pre-campaign period and 90 during the campaign period. The percentage of patients with care coordination increased from 3.5% (3/86) in the pre-campaign period to 14.4% (n = 13/90) during the campaign period. The percentage of patients who received OAC therapies, according to the definition from the Japanese AF medication guideline, increased from 55.8% (48/86) to 71.1% (64/90) during the campaign period regardless of care coordination. Younger patients were referred to cardiovascular specialists for care coordination. Implementation of OAC therapy did not differ between patients with and without care coordination. Adherence to OAC therapy was low regardless of care coordination. Conclusions This GP-targeted campaign was effective at raising awareness regarding the implementation of care coordination and appropriate OAC therapy at local clinical practices in Japan. Improvement of adherence to OAC therapy in elderly patients is a critical issue, and measures such as education programs targeted to patients and healthcare professionals should be undertaken.

scholarly journals Comparison of the native prothrombin antigen and the prothrombin time for monitoring oral anticoagulant therapy

Blood ◽  
1984 ◽  
Vol 64 (2) ◽  
pp. 445-451 ◽  
Author(s):  
B Furie ◽  
HA Liebman ◽  
RA Blanchard ◽  
MS Coleman ◽  
SF Kruger ◽  
...  
Keyword(s):  
Prothrombin Time ◽  
Anticoagulant Therapy ◽  
Oral Anticoagulant ◽  
Warfarin Therapy ◽  
Oral Anticoagulant Therapy ◽  
Bleeding Complications ◽  
Thromboembolic Complications ◽  
Serum Samples ◽  
Time Index ◽  
Patients At Risk

Abstract We have measured the fully carboxylated (native) prothrombin antigen and the undercarboxylated (abnormal) prothrombin antigen in patients treated with sodium warfarin using specific immunoassays to evaluate a new approach for monitoring oral anticoagulant therapy. Plasma and serum samples (391) were assayed for the prothrombin time, native prothrombin antigen, and abnormal prothrombin antigen. The results were correlated with the presence of bleeding or thromboembolic complications at the time of phlebotomy. The native prothrombin antigen correlated with the occurrence of complications in 95% of samples. Of 13 samples from patients with bleeding complications, 13/13 (100%) had a native prothrombin of 12 micrograms/mL or lower. Of seven samples from patients with thromboembolic complications, 6/7 (86%) had a native prothrombin of 24 micrograms/mL or greater. By comparison, a prothrombin time index of 1.5 to 2.5, 1.5 to 2.2, 1.5 to 2.0, or 1.3 to 1.8 identified 6/20 (30%), 9/20 (45%), 11/20 (55%), or 12/20 (60%) patients at risk, respectively. Although the prothrombin time index did correlate with the presence of bleeding complications, the native prothrombin antigen correlated closely with the presence of bleeding and thromboembolic complications. According to these results, the native prothrombin antigen, maintained in a range of 12 to 24 micrograms/mL by regular adjustment of the warfarin dosage, may be associated with a reduced risk of complications due to excessive or insufficient warfarin therapy. On the basis of these preliminary data, we recommend that the native prothrombin antigen be considered to monitor warfarin therapy.

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