Time in therapeutic range

Time in therapeutic range estimates the time a patient remains in the narrow therapeutic range of an international normalized ratio (INR) of 2-3. Going above this range increase your bleeding risk while going below steeply increases the risk of stroke.

Cross trial comparisons of TTR are hampered by variations in:

A higher CHADS score is associated with a lower TTR. Sicker patients may have reduced access to frequent testing.

The presence of congestive heart failure Varying drug clearance and distribution (CHF: 63% in ROCKET, 32% RELY, 35% ARISTOTLE)

The TTR is highest in Scandanavian countries (70% to 80%), and lowest in developing countries (40% to 50%)

Comparison of results across trials in TTR are inappropriate unless the TTR in each country should be compared, ROCKET AF in those countries who conducted RE-LY and vice versa (adjusting for the number of sites in each country).