Comparison among patients who did and did not reach target anti-Xa levels
| Target anti-Xa | Never on-target anti-Xa | P value | |
| n=195 | n=85 | ||
| Male (%) | 78.9% | 82.4% | 0.503 |
| Age (median, IQR) | 35 (24–56) | 36 (26–50) | 0.884 |
| Mechanism (%) | |||
| Blunt | 56.2% | 51.9% | 0.533 |
| Penetrating injury | 43.8% | 48.1% | |
| History of VTE (%) | 1.0% | 2.4% | 0.396 |
| ISS (median, IQR) | 14 (9–26) | 18 (10–26) | 0.927 |
| BMI (median, IQR) | 24.4 (22.0–28.2) | 25.2 (22.3–29.5) | 0.409 |
| ICU length of stay (days; median, IQR) | 5 (2 - 9) | 3 (2 - 5) | 0.003 |
| Hospital length of stay (days; median, IQR) | 12 (7–21) | 8 (5 - 15) | 0.019 |
| Admission INR (median, IQR) | 1.1 (1.0–1.2) | 1.1 (1.0–1.2) | 0.922 |
| Creatinine clearance (median, IQR) | 117 (90–150) | 147 (110–183) | 0.039 |
| First enoxaparin dose (%) | |||
| 30 mg two times per day | 95.9% | 95.3% | 0.520 |
| 40 mg two times per day | 3.1% | 4.7% | |
| 60 mg two times per day | 1.0% | 0.0% | |
| Hours to enoxaparin initiation (median, IQR) | 31 (16–67) | 31 (19–43) | 0.079 |
| Total anti-Xa levels collected (median, IQR) | 1 (1-2) | 1 (1-2) | 0.050 |
| Dose modifications made (median, IQR) | 0 (0–1) | 0 (0–1) | 0.361 |
| Final enoxaparin dose (%) | |||
| 30 mg two times per day | 61.9% | 49.4% | 0.009 |
| 40 mg two times per day | 26.3% | 41.1% | |
| 60 mg two times per day | 10.8% | 4.7% | |
| 80 mg two times per day | 1.0% | 2.4% | |
| 100 mg two times per day | 0.0% | 2.4% | |
| Median anti-Xa level by dose (median, IQR) | |||
| 30 mg two times per day | 0.24 (0.22–0.29) | 0.21 (0.07–0.16) | <0.001 |
| 40 mg two times per day | 0.26 (0.22–0.30) | 0.12 (0.07–0.14) | <0.001 |
| 60 mg two times per day | 0.33 (0.26–0.39) | 0.07 (0.05–0.09) | 0.038 |
| 80 mg two times per day | 0.40 (0.39–0.41) | 0.04 (0.04–0.04) | 0.035 |
| 100 mg two times per day | n/a | 0.15 (0.14–0.17) | – |
| Major bleeding (%) | 3.1% | 0.0% | 0.101 |
| Venous thromboembolic events (%) | 9.3% | 9.4% | 0.972 |
| Mortality (%) | 1.0% | 1.1% | 0.914 |
BMI, body mass index; ICU, intensive care unit; INR, international normalized ratio; IQR, interquartile range; ISS, Injury Severity Score; VTE, venous thromboembolism.