Table 1. Demographic and Clinical Factors of Participants in the Genetic Informatics Trial of Warfarin to Prevent Deep Vein Thrombosis.
| Warfarin Dosing | ||
|---|---|---|
| Genotype-Guided (n = 808) |
Clinically Guided (n = 789) |
|
| Age, mean (SD), y | 72.2 (5.3) | 72.0 (5.5) |
| Body mass index, mean (SD)a | 29.3 (5.6) | 29.0 (5.4) |
| Body surface area, mean (SD), m2 | 1.92 (0.25) | 1.92 (0.24) |
| Baseline international normalized ratio | 1.0 (0.1) | 1.0 (0.1) |
| Arthroplasty indication, No. (%) | ||
| Hip replacement | 207 (25.6) | 199 (25.2) |
| Knee replacement | 601 (74.4) | 590 (74.8) |
| Target international normalized ratio, No. (%) | ||
| 1.8 | 406 (50.2) | 398 (50.4) |
| 2.5 | 402 (49.8) | 391 (49.6) |
| Female sex, No. (%) | 522 (64.6) | 496 (62.9) |
| High-risk subgroup, No./total (%)b | 323/808 (40.0) | 335/789 (42.5) |
| Race, No. (%) | ||
| Black | 52 (6.4) | 50 (6.3) |
| American Indian or Alaskan Native | 1 (0.1) | 0 |
| Asian or Indian subcontinent | 16 (2.0) | 13 (1.6) |
| White | 735 (91.0) | 719 (91.1) |
| Otherc | 4 (0.5) | 7 (0.9) |
| Hispanic, No. (%) | 17 (2.1) | 25 (3.2) |
| History, No. (%) | ||
| Smoking | 21 (2.6) | 33 (4.2) |
| Diabetes | 116 (14.4) | 105 (13.3) |
| Liver disease | 6 (0.7) | 6 (0.8) |
| Venous thromboembolism | 6 (0.7) | 6 (0.8) |
| Drugs that interact with warfarin, No. (%)d | ||
| Sulfamethoxazole | 4 (0.5) | 2 (0.3) |
| Fluconazole or other azole | 3 (0.4) | 2 (0.3) |
| Statin | 365 (45.2) | 402 (51.0) |
| CYP2C9 inducerd,e | 3 (0.4) | 3 (0.4) |
| Amiodarone | 0 | 3 (0.4) |
a
Calculated as weight in kilograms divided by height in meters squared.
b
Consists of patients whose clinically guided vs genotype-predicted warfarin doses differed by 1.0 mg/d or greater (according to baseline genotype and clinical algorithms).
c
Pacific Islander, mixed race, or self-identified as other.
d
Prescribed during initial 11 days of therapy.
e
Carbamazepine, phenobarbital, phenytoin, or rifampin.