Dosing Algorithm for Warfarin Using CYP2C9 and VKORC1 Genotyping From a Multi-Ethnic Population: Comparison with Other Equations

Abstract

Minor improvements in algorithms can be observed with the inclusion of ethnicity and more CYP2C9 and VKORC1 SNPs as variables. Major improvements will likely require the identification of new gene associations with warfarin dosing.

Validation of Clinical Testing for Warfarin Sensitivity

“…The Newcastle algorithm performed the least well and tended to underdose patients, perhaps because it includes height but not body mass index or weight. Wu and colleagues 14 compared several dosing algorithms in a multiethnic American population and found a similar correlation with actual warfarin dose as in our study (r ϭ 0.64 to 0.68) with similar worse correlation for the Newcastle algorithm (r ϭ 0.55). Although the Wash U algorithm requires that more clinical information be gathered on each patient, it did not perform better than the UCSF algorithm in our population.…”

“…There may be factors unique to different geographic or demographic groups that affect the efficacy of dosing algorithms derived from a specific patient population. Wu and colleagues 14 predictably found the best correlation with warfarin dose using the training set of patients that was used to derive their own algorithm. Because ours was a small retrospective analysis, there may have been missing or confounding factors that were not taken into account, or the results may be skewed by individual patients.…”

“…We compared the accuracy of four published algorithms for determining warfarin dosage, herein called Wash U, 13 UCSF, 14 Louisville, 15 and Newcastle, 16 using retrospective data from a local patient population on long-term, stable warfarin therapy.…”

Accuracy assessment of pharmacogenetic algorithms for warfarin dose prediction in Chinese patients

“…Algorithms were selected based on the following criteria: the algorithms that included nongenetic or genetic variables not available in our study, and included only a minority of clinical variables, and were based on relatively small clinical populations were excluded; algorithms that were derived from Asian with the consideration of race of each algorithm made up of at least 15% Asians in original populations, and algorithms validated best in Asians were included. This process identified eight algorithms [12][13][14][15][16][17][18][19]. The characteristics and equations of selected algorithms are listed in Supporting Information Tables II and III. Collection of subjects and clinical data.…”

“…In the interest of determining an accurate predictive pharmacogenetic algorithm to promote rational treatment, especially for Chinese outliers, we attempted to assess the predictive ability of published warfarin pharmacogenetic dosing algorithms in Mainland Han Chinese [12][13][14][15][16][17][18][19].…”