This Figure illustrates a very simple concept: in this retrospective study of >6,000 patients in the United Kingdom, freedom from risk of stroke is greatly increased for patients who are kept within the INR 2–3 therapeutic window between 70% and 100% of the time.  This benefit decreases dramatically, however, when the %-time in therapeutic range (TTR) decreases to <70%.[75]

Rothman SA. Am J Med 2013; 126: 00-00.