Effect of Predictors on Treatment With Warfarin
| Predictor . | Dose to Achieve Target INR (mg/kg) . | Dose to Maintain Target INR (mg/kg) . | Day of Heparin Therapy That Warfarin Was Initiated . | Overlap of Warfarin Therapy With Heparin Therapy (d) . | Amount of Time Taken to Achieve Target INR (d) . | Mean No. of Tests/ mo . | Mean No. of Dose Changes/ mo . | INR Measurements Within Target Range (%) . | INR Measure- ments < Target (%) . | INR Measure- ments > Target (%) . |
|---|---|---|---|---|---|---|---|---|---|---|
| Age in years | ||||||||||
| ≤1 | 0.34 ± 0.16 | 0.33 ± 0.20 | 7.8 ± 6.5 | 6.3 ± 4.9 | 9.7 ± 8.1 | 8.1 ± 5.5 | 3.6 ± 2.0 | 37 ± 16 | 46 ± 17 | 16 ± 12 |
| >1 < 6 | 0.19 ± 0.11 | 0.15 ± 0.10 | 6.7 ± 8.2 | 4.7 ± 4.2 | 6.1 ± 9.0 | 5.7 ± 3.4 | 2.4 ± 1.6 | 45 ± 18 | 40 ± 18 | 15 ± 12 |
| ≥6 < 13 | 0.15 ± 0.07 | 0.13 ± 0.06 | 4.8 ± 3.7 | 4.4 ± 4.1 | 4.7 ± 5.6 | 4.6 ± 4.0 | 1.8 ± 2.2 | 54 ± 18 | 34 ± 18 | 13 ± 11 |
| ≥13 ≤ 18 | 0.14 ± 0.05 | 0.09 ± 0.05 | 5.0 ± 3.0 | 3.6 ± 1.8 | 3.8 ± 2.8 | 3.8 ± 3.0 | 1.5 ± 1.7 | 53 ± 19 | 32 ± 16 | 15 ± 11 |
| P value | <.0001 | <.0001 | .03 | .001 | <.0001 | <.0001 | <.0001 | <.0001 | <.0001 | NS |
| INR | ||||||||||
| 1.4-1.8 | 0.12 ± 0.07 | 0.11 ± 0.08 | 3.7 ± 1.9 | 2.7 ± 2.9 | 5.5 ± 5.4 | 2.7 ± 2.5 | 1.0 ± 1.3 | 49 ± 21 | 35 ± 18 | 16 ± 13 |
| 2.0-3.0 | 0.20 ± 0.12 | 0.16 ± 0.13 | 6.4 ± 6.1 | 4.6 ± 3.7 | 6.0 ± 7.6 | 5.9 ± 4.0 | 2.5 ± 1.8 | 47 ± 18 | 38 ± 17 | 15 ± 12 |
| 2.5-3.5 | 0.17 ± 0.09 | 0.14 ± 0.09 | 4.0 ± 6.0 | 5.2 ± 6.0 | 4.2 ± 4.2 | 2.7 ± 1.7 | 1.4 ± 2.2 | 61 ± 20 | 30 ± 20 | 9 ± 6 |
| P value | .02 | NS | NS | NS | NS | <.0001 | <.0001 | .011 | NS | .02 |
| Disease | ||||||||||
| CHD | 0.20 ± 0.13 | 0.17 ± 0.14 | 5.2 ± 4.5 | 4.2 ± 4.4 | 6.9 ± 8.4 | 5.4 ± 4.4 | 2.2 ± 1.8 | 46 ± 17 | 40 ± 17 | 14 ± 11 |
| Non-CHD | 0.18 ± 0.12 | 0.15 ± 0.14 | 6.1 ± 4.8 | 5.0 ± 3.6 | 4.6 ± 4.0 | 4.8 ± 3.7 | 2.0 ± 2.0 | 50 ± 21 | 35 ± 19 | 15 ± 12 |
| Fontan* | 0.18 ± 0.08 | 0.12 ± 0.07 | 8.0 ± 12.1 | 4.2 ± 4.0 | 5.9 ± 10.0 | 6.1 ± 3.5 | 2.6 ± 1.5 | 48 ± 16 | 36 ± 16 | 15 ± 10 |
| P value | .02 | .003 | NS | .03 | NS | .002 | .002 | NS | NS | NS |
| Medication | ||||||||||
| Corticosteroids | ||||||||||
| Yes | 0.18 ± 0.08 | 0.11 ± 0.08 | 4.6 ± 2.4 | 3.7 ± 2.5 | 3.7 ± 3.1 | 5.2 ± 3.6 | 2.3 ± 2.0 | 43 ± 21 | 36 ± 17 | 21 ± 11 |
| No | 0.19 ± 0.12 | 0.16 ± 0.13 | 6.3 ± 6.4 | 4.7 ± 4.0 | 5.9 ± 7.5 | 5.2 ± 4.0 | 2.1 ± 1.9 | 49 ± 19 | 37 ± 18 | 14 ± 11 |
| P value | NS | NS | NS | NS | NS | NS | NS | .02 | NS | .002 |
| Phenobarbital/ Carbamazepine | ||||||||||
| Yes | 0.24 ± 0.15 | 0.24 ± 0.17 | 7.7 ± 4.0 | 6.3 ± 4.5 | 6.6 ± 4.5 | 4.5 ± 3.5 | 2.0 ± 2.3 | 55 ± 22 | 32 ± 24 | 13 ± 8 |
| No | 0.19 ± 0.12 | 0.15 ± 0.13 | 6.0 ± 6.1 | 4.6 ± 3.9 | 5.7 ± 7.3 | 5.2 ± 4.0 | 2.2 ± 1.9 | 48 ± 19 | 37 ± 17 | 15 ± 12 |
| P value | NS | .006 | NS | NS | NS | NS | NS | NS | NS | NS |
| Diet | ||||||||||
| Enteral nutrition | ||||||||||
| Yes | 0.28 ± 0.16 | 0.26 ± 0.18 | 8.6 ± 8.9 | 6.4 ± 4.9 | 8.0 ± 10.0 | 6.8 ± 4.7 | 2.9 ± 1.8 | 41 ± 15 | 43 ± 15 | 16 ± 12 |
| No | 0.16 ± 0.07 | 0.11 ± 0.07 | 4.9 ± 3.7 | 3.9 ± 3.2 | 5.0 ± 5.7 | 4.7 ± 3.6 | 1.9 ± 1.9 | 51 ± 20 | 35 ± 18 | 14 ± 11 |
| P value | .005 | <.0001 | <.0001 | <.0001 | NS | NS | NS | NS | NS | NS |
| Predictor . | Dose to Achieve Target INR (mg/kg) . | Dose to Maintain Target INR (mg/kg) . | Day of Heparin Therapy That Warfarin Was Initiated . | Overlap of Warfarin Therapy With Heparin Therapy (d) . | Amount of Time Taken to Achieve Target INR (d) . | Mean No. of Tests/ mo . | Mean No. of Dose Changes/ mo . | INR Measurements Within Target Range (%) . | INR Measure- ments < Target (%) . | INR Measure- ments > Target (%) . |
|---|---|---|---|---|---|---|---|---|---|---|
| Age in years | ||||||||||
| ≤1 | 0.34 ± 0.16 | 0.33 ± 0.20 | 7.8 ± 6.5 | 6.3 ± 4.9 | 9.7 ± 8.1 | 8.1 ± 5.5 | 3.6 ± 2.0 | 37 ± 16 | 46 ± 17 | 16 ± 12 |
| >1 < 6 | 0.19 ± 0.11 | 0.15 ± 0.10 | 6.7 ± 8.2 | 4.7 ± 4.2 | 6.1 ± 9.0 | 5.7 ± 3.4 | 2.4 ± 1.6 | 45 ± 18 | 40 ± 18 | 15 ± 12 |
| ≥6 < 13 | 0.15 ± 0.07 | 0.13 ± 0.06 | 4.8 ± 3.7 | 4.4 ± 4.1 | 4.7 ± 5.6 | 4.6 ± 4.0 | 1.8 ± 2.2 | 54 ± 18 | 34 ± 18 | 13 ± 11 |
| ≥13 ≤ 18 | 0.14 ± 0.05 | 0.09 ± 0.05 | 5.0 ± 3.0 | 3.6 ± 1.8 | 3.8 ± 2.8 | 3.8 ± 3.0 | 1.5 ± 1.7 | 53 ± 19 | 32 ± 16 | 15 ± 11 |
| P value | <.0001 | <.0001 | .03 | .001 | <.0001 | <.0001 | <.0001 | <.0001 | <.0001 | NS |
| INR | ||||||||||
| 1.4-1.8 | 0.12 ± 0.07 | 0.11 ± 0.08 | 3.7 ± 1.9 | 2.7 ± 2.9 | 5.5 ± 5.4 | 2.7 ± 2.5 | 1.0 ± 1.3 | 49 ± 21 | 35 ± 18 | 16 ± 13 |
| 2.0-3.0 | 0.20 ± 0.12 | 0.16 ± 0.13 | 6.4 ± 6.1 | 4.6 ± 3.7 | 6.0 ± 7.6 | 5.9 ± 4.0 | 2.5 ± 1.8 | 47 ± 18 | 38 ± 17 | 15 ± 12 |
| 2.5-3.5 | 0.17 ± 0.09 | 0.14 ± 0.09 | 4.0 ± 6.0 | 5.2 ± 6.0 | 4.2 ± 4.2 | 2.7 ± 1.7 | 1.4 ± 2.2 | 61 ± 20 | 30 ± 20 | 9 ± 6 |
| P value | .02 | NS | NS | NS | NS | <.0001 | <.0001 | .011 | NS | .02 |
| Disease | ||||||||||
| CHD | 0.20 ± 0.13 | 0.17 ± 0.14 | 5.2 ± 4.5 | 4.2 ± 4.4 | 6.9 ± 8.4 | 5.4 ± 4.4 | 2.2 ± 1.8 | 46 ± 17 | 40 ± 17 | 14 ± 11 |
| Non-CHD | 0.18 ± 0.12 | 0.15 ± 0.14 | 6.1 ± 4.8 | 5.0 ± 3.6 | 4.6 ± 4.0 | 4.8 ± 3.7 | 2.0 ± 2.0 | 50 ± 21 | 35 ± 19 | 15 ± 12 |
| Fontan* | 0.18 ± 0.08 | 0.12 ± 0.07 | 8.0 ± 12.1 | 4.2 ± 4.0 | 5.9 ± 10.0 | 6.1 ± 3.5 | 2.6 ± 1.5 | 48 ± 16 | 36 ± 16 | 15 ± 10 |
| P value | .02 | .003 | NS | .03 | NS | .002 | .002 | NS | NS | NS |
| Medication | ||||||||||
| Corticosteroids | ||||||||||
| Yes | 0.18 ± 0.08 | 0.11 ± 0.08 | 4.6 ± 2.4 | 3.7 ± 2.5 | 3.7 ± 3.1 | 5.2 ± 3.6 | 2.3 ± 2.0 | 43 ± 21 | 36 ± 17 | 21 ± 11 |
| No | 0.19 ± 0.12 | 0.16 ± 0.13 | 6.3 ± 6.4 | 4.7 ± 4.0 | 5.9 ± 7.5 | 5.2 ± 4.0 | 2.1 ± 1.9 | 49 ± 19 | 37 ± 18 | 14 ± 11 |
| P value | NS | NS | NS | NS | NS | NS | NS | .02 | NS | .002 |
| Phenobarbital/ Carbamazepine | ||||||||||
| Yes | 0.24 ± 0.15 | 0.24 ± 0.17 | 7.7 ± 4.0 | 6.3 ± 4.5 | 6.6 ± 4.5 | 4.5 ± 3.5 | 2.0 ± 2.3 | 55 ± 22 | 32 ± 24 | 13 ± 8 |
| No | 0.19 ± 0.12 | 0.15 ± 0.13 | 6.0 ± 6.1 | 4.6 ± 3.9 | 5.7 ± 7.3 | 5.2 ± 4.0 | 2.2 ± 1.9 | 48 ± 19 | 37 ± 17 | 15 ± 12 |
| P value | NS | .006 | NS | NS | NS | NS | NS | NS | NS | NS |
| Diet | ||||||||||
| Enteral nutrition | ||||||||||
| Yes | 0.28 ± 0.16 | 0.26 ± 0.18 | 8.6 ± 8.9 | 6.4 ± 4.9 | 8.0 ± 10.0 | 6.8 ± 4.7 | 2.9 ± 1.8 | 41 ± 15 | 43 ± 15 | 16 ± 12 |
| No | 0.16 ± 0.07 | 0.11 ± 0.07 | 4.9 ± 3.7 | 3.9 ± 3.2 | 5.0 ± 5.7 | 4.7 ± 3.6 | 1.9 ± 1.9 | 51 ± 20 | 35 ± 18 | 14 ± 11 |
| P value | .005 | <.0001 | <.0001 | <.0001 | NS | NS | NS | NS | NS | NS |
Data are reported as mean ± 1 SD. Each statistically significant relationship is highlighted.
Abbreviations: CHD, congenital heart disease; NS, not significant.
Fontan patients received an initial loading dose of warfarin of 0.1 mg/kg in contrast to the standard loading dose of 0.2 mg/kg.