Control of oral anticoagulant therapy

Area of Science:

• Clinical Chemistry
• Hematology
• Pharmacology

Background:

• Oral anticoagulant therapy requires standardized monitoring for efficacy and safety.
• Variability in prothrombin time testing can lead to inconsistent therapeutic outcomes.
• Recent data suggest a high incidence of over-anticoagulation in American patients.

Purpose of the Study:

• To evaluate the effectiveness of the International Normalized Ratio (INR) in standardizing oral anticoagulant therapy.
• To assess the impact of INR on interlaboratory comparisons.
• To identify the prevalence of supratherapeutic anticoagulation levels in a patient population.

Main Methods:

• Reporting prothrombin time as INR.
• Calibrating local thromboplastin with an International Reference Preparation.
• Analyzing patient specimen results against recommended therapeutic ranges.

Main Results:

• The INR effectively minimized discrepancies caused by variations in thromboplastin sources and instrumentation.
• The INR facilitates improved interlaboratory comparability of coagulation test results.
• Over 40% of analyzed patient specimens exhibited INR values exceeding currently recommended therapeutic levels.

Conclusions:

• The INR is a valuable tool for standardizing oral anticoagulant therapy monitoring.
• Implementation of INR reporting can enhance the reliability and consistency of coagulation testing.
• A significant proportion of patients are potentially at increased risk of bleeding due to over-anticoagulation.