Table 1.
Characteristics of the Patients at Baseline.*
| Characteristic | Genotyped-Guided Group (N = 514) | Clinically Guided Group (N = 501) |
|---|---|---|
| Median age (IQR) — yr† | 59 (48–70) | 57 (46–68) |
| Male sex — no. (%) | 272 (53) | 246 (49) |
| Race or ethnic group — no. (%)‡ | ||
| Black† | 141 (27) | 134 (27) |
| Hispanic | 32 (6) | 33 (7) |
| Education — no. (%) | ||
| Did not complete high school | 52 (10) | 44 (9) |
| High-school diploma only | 131 (25) | 133 (27) |
| Post-secondary education | 308 (60) | 291 (58) |
| Did not respond | 23 (4) | 33 (7) |
| Current smoker — no. (%)† | 77 (15) | 68 (14) |
| Median body-surface area (IQR) — m2† | 2.01 (1.83–2.19) | 2.03 (1.85–2.23) |
| Warfarin and other therapies — no. (%) | ||
| Inpatient warfarin initiation | 348 (68) | 332 (66) |
| Indication for warfarin therapy | ||
| Deep-vein thrombosis or pulmonary embolism only | 289 (56) | 300 (60) |
| Atrial fibrillation or flutter only | 116 (23) | 105 (21) |
| Other indication only | 56 (11) | 53 (11) |
| Multiple indications | 49 (10) | 39 (8) |
| No indication given | 4 (1) | 4 (1) |
| Deep-vein thrombosis or pulmonary embolism as primary indication† | 305 (59) | 317 (63) |
| Expected duration of warfarin therapy | ||
| <1 mo | 33 (6) | 33 (7) |
| 1–3 mo | 35 (7) | 30 (6) |
| >3 mo | 446 (87) | 438 (87) |
| Previous warfarin use | 38 (7) | 48 (10) |
| Current amiodarone use† | 13 (3) | 10 (2) |
| Current fluvastatin use† | 2 (<1) | 1 (<1) |
| Current heparin use | 278 (54) | 281 (56) |
| Medical history — no. (%) | ||
| Congestive heart failure | 63 (12) | 64 (13) |
| Deep-vein thrombosis | 149 (29) | 146 (29) |
| Diabetes† | 118 (23) | 121 (24) |
| Hypertension | 280 (54) | 260 (52) |
| Myocardial infarction | 47 (9) | 48 (10) |
| Pulmonary embolism | 109 (21) | 105 (21) |
| Stroke† | 37 (7) | 31 (6) |
| Genetic variants — no. (%) | ||
| CYP2C9*2† | ||
| No variants | 414 (81) | 423 (84) |
| Heterozygous | 92 (18) | 70 (14) |
| Homozygous | 4 (1) | 7 (1) |
| Withdrew before genotyping | 4 (1) | 1 (<1) |
| CYP2C9*3† | ||
| No variants | 471 (92) | 451 (90) |
| Heterozygous | 38 (7) | 49 (10) |
| Homozygous | 1 (<1) | 0 |
| Withdrew before genotyping | 4 (1) | 1 (<1) |
| VKORC1 (VKORC1 3673G A)† | ||
| No variants (GG) | 250 (49) | 237 (47) |
| Heterozygous (AG or GA) | 201 (39) | 202 (40) |
| Homozygous (AA) | 59 (11) | 61 (12) |
| Withdrew before genotyping | 4 (1) | 1 (<1) |
| Total no. of variants§ | ||
| 0 | 204 (40) | 189 (38) |
| 1 | 178 (35) | 186 (37) |
| >1 | 128 (25) | 125 (25) |
| Withdrew before genotyping | 4 (1) | 1 (<1) |
*
There were no significant between-group differences for any characteristic. IQR denotes interquartile range.
†
This variable was used in the algorithms for dose initiation and dose revision in the two study groups. Dosing algorithms are provided in the Supplementary Appendix.
‡
Race or ethnic group was self-reported.
§
The total number of variants was defined as the number of measured variants in CYP2C9*2, CYP2C9*3, and VKORC1.