Real-life contemporary vitamin K antagonist is still associated with very low time in therapeutic range despite strict international normalized ratio monitoring: Results of big data analysis.

What Is Known And Objective: This study aimed to determine the results of INR monitoring in patients on vitamin K antagonists (VKAs) and the time in therapeutic range (TTR) in 'real-world' settings.

Methods: Retrospective analysis of 836,857 INR measurements performed in adults from February 2010 to August 2015 in two districts in the French Brittany region.

Results: Of the 836,857 INR measurements, 94.