Accuracy and precision of the CoaguChek S versus laboratory INRs in a clinic.

Background: The CoaguChek S is the next-generation coagulation monitor for measuring the international normalized ratio (INR) that replaces the CoaguChek device. Studies are lacking comparing the CoaguChek S with local laboratory INR assessment to ensure its accuracy and precision for monitoring patients on anticoagulation.

Objective: To evaluate accuracy, precision, and technical ease-of-use of the CoaguChek S compared with laboratory measurements.

Effect of stress on international normalized ratio during warfarin therapy.

Objective: To discuss the effect of stress on the international normalized ratio (INR) when patients are taking warfarin.

Case Summary: Two patients at a pharmacist-managed anticoagulation clinic who were stable with anticoagulation developed elevated INR values after a stressful event occurred. All other factors known to elevate the INR were unchanged; furthermore, the INR values returned to the prior level of control after resolution of the stressful events.