| Outcome | No. of studies | No. of patients | Mean difference (95% CI) | I2 |
|---|---|---|---|---|
| Mortality | ||||
| Overall | 9 | 372 | 21.49 (12.57 to 30.41) | 70 |
| Evaluation time | ||||
| 6 mo | 1 | 85 | - | - |
| Sampling time | ||||
| Up to 12 hr | 4 | 234 | 21.00 (6.67 to 35.32) | 80 |
| Type of sample | ||||
| Venous | 4 | 151 | 32.31 (13.76 to 50.85) | 59 |
| Biochemical analysis | ||||
| ELISA | 2 | 169 | - | - |
| Minimal TBI severity | ||||
| Severe | 5 | 166 | 15.99 (7.59 to 24.39) | 63 |
| Isolated TBI | ||||
| Isolated | 2 | 133 | - | - |
| GOS or GOSE | ||||
| Overall | 13 | 501 | 18.21 (12.95 to 23.47) | 63 |
| Evaluation time | ||||
| 6 mo | 3 | 166 | 20.49 (14.27 to 26.72) | 0 |
| Sampling time | ||||
| Up to 12 hr | 7 | 298 | 19.39 (15.59 to 23.20) | 0 |
| Type of sample | ||||
| Venous | 6 | 270 | 18.35 (10.68 to 26.02) | 72 |
| Biochemical analysis | ||||
| ELISA | 4 | 180 | 23.34 (14.89 to 31.79) | 0 |
| Minimal TBI severity | ||||
| Severe | 7 | 229 | 18.01 (14.08 to 21.94) | 6 |
| Isolated TBI | ||||
| Isolated | 5 | 244 | 16.55 (12.47 to 20.63) | 11 |
Note: CI = confidence interval, ELISA = enzyme-linked immunosorbent assay, GOS = Glasgow Outcome Scale, GOSE = Glasgow Outcome Scale-Extended, TBI = traumatic brain injury.