This study was conducted to determine the reliability of two methods of predicting maintenance warfarin dosage. Fifty-nine patients were studied using Method 1 and 44 using Method 2. Both methods produced a statistically significant correlation between predicted and actual dose for the two populations. However, actual vs. predicted doses for individual patients were significantly different. Method 1 predicted a dose within ± 2.5 mg/d of actual dose in only 40.7 percent of patients. With Method 2, the corresponding value was 56.8 percent. Although the linear regression was statistically significant in our population, many patients would have excessive or subtherapeutic dosage predictions.
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