Evaluation of Different Thromboplastins and Coagulometers on International Normalize Ratio (INR) Readings for Patients under Stable Oral Anticoagulant Therapy

Rasha M. Ahmed and Abdel Rahim M. Muddathir

Background: Variations between various thromboplastin preparations have in the past led to decreased accuracy of INR readings. Because thromboplastin reagents vary widely in composition and manner of preparation, their sensitivity in monitoring oral anticoagulant therapy also vary widely. This study aimed to evaluate different thromboplastins and coagulometers on INR reading for patients under stable oral anticoagulant therapy.

Materials and Methods: This was descriptive cross-sectional study; it was conducted in three hospitals (Alshaab teaching hospital, Khartoum teaching hospital, and Turkish hospital). A total of 50 citrated platelets poor plasma samples were collected from 50 Sudanese patients under stable oral anticoagulant therapy then prothrombin time (PT) and INR measurements were performed on three separated laboratories, using different coagulometers and thromboplastins reagents.

Results: INR results showed that there was significant difference between INR of the three laboratories (P value=0.00), inspite of there was significant difference observed between INR in Khartoum hospital and Alshaab hospital, also between Alshaab and Turkish hospital (p-value=0.00). There was insignificant difference between INR in Khartoum hospital and Trukish hospital (p-value=0.178). Discussion and

Conclusion: our investigation showed that some further efforts are needed to achieve harmonization of INR results among different laboratories because variation would most probably induce the clinician to make a change in warfarin dose. Standardization of instruments, reagents, and controls is warranted to decrease this variation.