What is the relative risk reduction of using Rivaroxaban over Enoxaparin?

In a study where Rivaroxaban was compared to enoxaparin to find total VTE following HIP replacement surgery, there were 17 total VTE out of 1513 patients in the Rivaraoaban group and 57 total VTE out of 1473 patient in the enoxaparin group.

What is the relative risk reduction of using Rivaroxaban over Enoxaparin?
A . 39%
B . 71%
C . 29%
D . 14%
E . 42%

Answer: B

Explanation:

Relative risk reduction: 0.71 = 71% Relative risk: (Event rate in rivaroxaban group)/(Event rate in enoxaparin group) = (17/1513)/(57/1473) = 0.2903 Relative risk reduction: 1 C (relative risk) = 1 C 0.2903 = 0.7097 = 0.71.