Time in the Therapeutic Range (TTR): An Overly Simplified Conundrum

Abstract

Anticoagulation with warfarin has been used for over 60 years; however, its administration is fraught with difficulty since many factors can affect warfarin dosing. The concept of time in therapeutic range (TTR) has become a popular way to report warfarin management and compare anticoagulation management across clinical trials. However, TTR is a much more complex concept than most clinicians and trialists recognize. This manuscript attempts to discuss some of the important factors underlying this complexity and presents a suggestion to improve reports on TTR.