Table 4.
Comparative influence of VKORC1 haplotype versus single predictive SNP on warfarin maintenance dose
| Predicted mean dose ± SD (mg/wk) | R2full model % | R2VKORC1 %* | |
|---|---|---|---|
| Asians (n = 247) | |||
| −1639G>A (rs9923231) | 21.55 ± 6.56 | 46.09 | 28.58 |
| VKORC1 haplotype | 21.55 ± 6.52 | 46.08 | 28.57 |
| Blacks (n = 365) | |||
| −1639G>A (rs9923231) | 40.79 ± 8.18 | 27.02 | 4.15 |
| VKORC1 haplotype | 40.80 ± 8.13 | 27.41 | 4.54 |
| Whites (n = 556) | |||
| −1639G>A (rs9923231) | 33.23 ± 11.02 | 50.94 | 23.16 |
| VKORC1 haplotype | 33.15 ± 11.06 | 51.53 | 23.75 |
The full, multivariable model is adjusted for CYP2C9 genotype, age, height, weight, CYP2C9 enzyme inducer status, and amiodarone status. Haplotype analysis and the “SNP versus haplotype comparison” were restricted to include participants with complete genotype data on all 6 SNPs.
*
Semi-partial R2 for VKORC1 SNP and haplotype in the multivariable model.