Monitor INR regularly in patients on vitamin K antagonists such as warfarin, calculating the time in therapeutic range (TTR) at each visit using validated methods like the Rosendaal method or proportion of tests in range, and excluding measurements taken during the first 6 weeks of treatment NICE NG196.
Reassess anticoagulation control if INR values are higher than 5 or 1 INR value higher than 8 within the past 6 months, or if INR values are less than 1.5, or if TTR is less than 65% NICE NG196.
Address factors contributing to poor control, such as adherence, illness, interacting drugs, lifestyle factors, and cognitive function, during reassessment NICE NG196.
For self-monitoring, patients should be trained to adjust warfarin doses based on INR results, participate in quality assurance schemes, and have regular reviews at least every 6 months NICE NG196.
Use point-of-care coagulometers, such as the CoaguChek XS system, for self-monitoring coagulation status, following NICE recommendations NICE NG196.