Key result
Day 3 INR after 2 days of warfarin 10 mg/day strongly correlated with the weekly maintenance dose required to achieve a therapeutic INR (r = 0.74, p < .0001).
Why the study?
Does day 3 INR after a 2-day 10 mg/day loading dose predict the weekly warfarin maintenance dose in outpatients with nonrheumatic atrial fibrillation?
Observational (n=84)
Does day 3 INR after a 2-day 10 mg/day loading dose predict the weekly warfarin maintenance dose in outpatients with nonrheumatic atrial fibrillation?
Effect estimate: r = 0.74
p-value: p=< .0001
Day 3 INR after a standardized 2-day loading dose of 10 mg/day warfarin can be used to estimate the weekly maintenance dose in patients with nonrheumatic atrial fibrillation.
May aid early warfarin dosing estimates in AF outpatients; hypothesis-generating and requires prospective validation.
Eighty-four outpatients with nonrheumatic atrial fibrillation starting oral anticoagulant treatment were adminis tered warfarin (10 mg/day) for the first 2 days of treatment. Prothrombin time, expressed as International Normalized Ratio (INR), was measured on day 3 and plotted against the weekly warfarin maintenance dose, defined as the dose able to maintain INR between 2.0 and 3.0 (therapeutic range) on three consecu tive occasions, 1 week apart. The data fit a regression line (r = 0.74, p < .0001) that we use to estimate the weekly maintenance dose of other patients.
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Pengo et al. (1998) conducted an observational in Nonrheumatic atrial fibrillation (n=84). Warfarin was evaluated on Correlation between day 3 INR and weekly warfarin maintenance dose (r = 0.74, p=< .0001). Day 3 INR after 2 days of warfarin 10 mg/day strongly correlated with the weekly maintenance dose required to achieve a therapeutic INR (r = 0.74, p < .0001).
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