Based on the following regression equation: Square root of warfarin weekly dose (mg/week) = 5.5691 − 0.0054 × (age in years) −2.9909 × (INR/ dose, mg/week) + 0.0157 × (weight in kg) + 0.5726 × 1 (if patient has heart valve prosthesis) or 0 (if no heart valve prosthesis) + 0.4333 × 1 (if patient has thromboembolic disease) or 0 (if no thromboembolic disease) −0.4442 × 1 (if prescribed simvastatin) or 0 (if no prescribed simvastatin) − 0.7748 × 1 (if prescribed amiodarone) or 0 (if not prescribed amiodarone) − 0.5115 × 1 (if patient has one CYP2C9 variant allele) or 0 (if not) − 1.1043 × 1 (if patient has 2 CYP2C9 variant alleles) or 0 (if not) − 0.8352 × 1 (if VKORC1 3673GA genotype) or 0 (if not) − 1.6841 × 1 (if VKORC1 3673AA genotype) or 0 (if not).

Correlation coefficient (r²) between weekly warfarin dose predicted by the dosing algorithm (predicted dose) and the dose actually taken by the patient (observed dose).