Table 1.
Patient Characteristics by IGF‐I Group
| Characteristic | All TBI Group | IGF‐I above Age‐Related Median | IGF‐I below Age‐Related Median | p, above vs belowa |
|---|---|---|---|---|
| No. | 39 | 22 | 17 | |
| Age at first scan, yr, median (IQR) | 30.5 (24.5–47.0) | 30.2 (24.3–47.6) | 34.5 (25.2–48.8) | 0.43 |
| Range | 19.6–66.9 | 19.6–62.2 | 21.3–66.9 | |
| Male, No. [%] | 33 [84.6] | 17 [77.3] | 16 [94.1] | 0.32 |
| Postmenopausal women, No. [%] | 3 [7.7] | 2 [9.1] | 1 [5.9] | 0.82 |
| BMI, kg/m2, median (IQR) | 25.3 (23.1–29.8) | 23.6 (19.6–29.0) | 25.3 (24.4–30.2) | 1.00 |
| Range | 17.0–35.0 | 17.0–32.3 | 21.3–35.0 | |
| Moderate–severe TBI, No. [%] | 34 [87.2] | 20 [90.6] | 14 [82.4] | 0.75 |
| Blast TBI, No. [%] | 13 [33.3] | 8 [36.3] | 5 [29.4] | 0.90 |
| Time since TBI, mo, median (IQR) | 16.3 (3.6–24.5) | 12.5 (4.0–25.9) | 17.2 (3.1–33.5) | 0.89 |
| Range | 1.47–571.0 | 1.5–571.0 | 1.5–102.9 | |
| Time between scans, mo, median (IQR) | 13.3 (12.1–14.9) | 12.4 (10.8–13.4) | 14.4 (13.1–15.1) | 0.08 |
| Range | 6.3–24.6 | 6.3–24.6 | 8.9–17.8 | |
| Absolute IGF‐I, nmol/l, median (IQR)b | 23.8 (19.2–29.5) | 28.2 (23.3–35.1) | 19.9 (16.8–23.7) | 0.02c |
| Range | 12.8–74.5 | 19.2–74.5 | 12.8–29.0 | |
| Age‐adjusted IGF‐I ratio, median (IQR) | 1.1 (0.9–1.2) | 1.2 (1.1–1.5) | 0.8 (0.8–0.9) | <0.001c |
| Range | 0.6–3.0 | 1.0–2.9 | 0.6–1.0 | |
| GHD, No. [%] | 4 [10.2] | 1 [4.5] | 3 [17.6] | 0.42 |
| Any pituitary deficiency, No. [%] | 7 [17.9] | 3 [13.6] | 4 [23.5] | 0.71 |
| Any structural brain abnormality, No. [%] | 30 [76.9] | 19 [86.4] | 11 [64.7] | 0.23 |
| ≥1 contusion | 20 [51.3] | 11 [28.2] | 9 [52.9] | 0.89 |
| No. of contusions, median (IQR)d | 1 (0–2) | 1 (0–1) | 1 (0–2) | 0.40 |
| Range | 0–5 | 0–2 | 0–5 | |
| ≥1 microbleed, No. [%] | 10 [25.6] | 8 [36.4] | 2 [11.8] | 0.17 |
| Superficial siderosis, No. [%] | 13 [33.3] | 6 [27.3] | 7 [41.2] | 0.57 |
| Diffuse axonal injury, No. [%] | 5 [12.8] | 3 [13.6] | 2 [11.8] | 0.76 |
IGF‐I groups refer to patients with an absolute IGF‐I concentration above the median‐for‐age or below the median‐for‐age.
a
Probability value for comparison of serum IGF‐I group using chi‐square test with Yates correction for categorical variables and Mann–Whitney U test for continuous variables.
b
To convert nmol/l to ng/ml, divide by 0.131.
c
Statistically significant.
d
Including those without any contusions.
BMI = body mass index; GHD = growth hormone deficiency; IGF‐I = insulin‐like growth factor‐I; IQR = interquartile range; TBI = traumatic brain injury.