Table 2.
Effect of clinical and genetic predictors implemented in the COAG trial on warfarin dose requirements by race
| Variable | Race combined* | Race stratified | P§ (race × predictor interaction) | |||||||
|---|---|---|---|---|---|---|---|---|---|---|
| European Americans† | African Americans‡ | |||||||||
| β | % Dose change (95% CI) | P | β | % Dose change (95% CI) | P | β | % Dose change (95% CI) | P | ||
| Intercept | 1.4564 | — | — | 1.4749 | — | — | 1.3163 | — | — | — |
| African American | −0.0992 | −9.44 (−13.57 to −5.11) | <.001 | — | — | — | — | — | — | — |
| Age, y | −0.0068 | −0.68 (−0.81 to −0.54) | <.001 | −0.0064 | −0.64 (−0.82 to −0.46) | <.001 | −0.0070 | −0.7 (−0.9 to −0.49) | <.001 | .67 |
| BSA, per m2 | 0.4219 | 52.48 (41.3 to 64.55) | <.001 | 0.4143 | 51.34 (37.33 to 66.78) | <.001 | 0.4411 | 55.44 (37.81 to 75.33) | <.001 | .73 |
| Current smoker | −0.0022 | −0.22 (−6.12 to 6.06) | .94 | −0.0046 | −0.45 (−9.08 to 8.99) | .92 | −0.0078 | −0.78 (−8.64 to 7.77) | .85 | .96 |
| VTE | 0.0512 | 5.26 (0.85 to 9.86) | .02 | 0.0574 | 5.91 (0.04 to 12.11) | .05 | 0.0374 | 3.81 (−2.68 to 10.73) | .26 | .65 |
| Amiodarone | −0.2245 | −20.1 (−25.11 to −14.76) | <.001 | −0.1906 | −17.36 (−23.39 to −10.85) | <.001 | −0.3146 | −26.99 (−35.24 to −17.7) | <.001 | .08 |
| CYP2C9*2|| | −0.1929 | −17.54 (−21.54 to −13.34) | <.001 | −0.2313 | −20.65 (−24.67 to −16.42) | <.001 | 0.0389 | 3.96 (−9.79 to 19.81) | .59 | <.001 |
| CYP2C9*3|| | −0.4183 | −34.19 (−38.5 to −29.57) | <.001 | −0.4221 | −34.43 (−38.92 to −29.61) | <.001 | −0.4246 | −34.6 (−46.11 to −20.63) | <.001 | .98 |
| VKORC1|| | −0.3016 | −26.03 (−28.45 to −23.54) | <.001 | −0.3330 | −28.32 (−30.92 to −25.63) | <.001 | −0.2058 | −18.6 (−24.21 to −12.57) | <.001 | .002 |
β denotes parameter estimates. Bold font denotes that the parameter estimates are significantly different by race.
CI, confidence interval; VTE, venous thromboembolism as primary indication for warfarin therapy (vs non-VTE indications such as atrial fibrillation).
The referent is a European American with wild-type genotype for the CYP2C9*2, CYP2C9*3, and VKORC1, nonsmoker, without VTE, and not on amiodarone.
The referent is a European American with wild-type genotype for the CYP2C9*2, CYP2C9*3, and VKORC1, nonsmoker, without VTE, and not on amiodarone.
The referent is an African American with wild-type genotype for the CYP2C9*2, CYP2C9*3, and VKORC1, nonsmoker, without VTE, and not on amiodarone.
P value for the difference in parameter estimates obtained by including interaction terms of predictors with race (African American vs European American) in the race-adjusted model.
CYP2C9*2, CYP2C9*3, and VKORC1 were included as additive: 0 if no variants, 1 if heterozygous, and 2 if homozygous for the variant allele.