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. 2015 May 29;126(4):539–545. doi: 10.1182/blood-2015-02-627042

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 to13.34) <.001 0.2313 20.65 (24.67 to16.42) <.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 to23.54) <.001 0.3330 28.32 (30.92 to25.63) <.001 0.2058 18.6 (24.21 to12.57) <.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.