ARGUMENTATION - 12

Source: NEJM - carenini@cs.pitt.edu

GENERAL QUESTION: At what min/max value or in what interval an index must be maintained in order to avoid/favor a particular event?

TECHNIQUE: Compare the distribution respect to the index of cases for which the event happened, with the distribution respect to the same index of cases for which the event did not happen. Build an odd-ratio diagrams like the one shown in panel C .

SPECIFIC QUESTION: At what min value the INR index (international normalized ratio to measure the intensity of anticoagulation) must be maintained in order to avoid a stroke?

TECHNIQUE APPLICATION: see caption.

PAPER CONCLUSIONS:"Among patients with atrial fibrillation, anticoagulant prophylaxis is effective at INRs of 2.0 or greater. Since previous studies have indicated that the risk of hemorrhage rises rapidly at INRs greated than 4.5 to 5.0, tight control of anticoagulant theraphy to maintain the INR between 2.0 and 3.0 is a better strategy than targeting lower, less effective levels of anticoagulation."

COMMENTS:

• Caption for Figure 1 is incorrect (I checked with the authors). Control patients didn't have strokes.