Impact of the SIGN guidelines on number of admissions and deaths from TBI per 100 000 Scottish population
| Outcome | Winter effect | Initial trend | First SIGN guideline | 4-hour target introduced | Second SIGN guideline | Durbin-Watson statistic |
| Admissions for TBI/100 000 | −0.04 (95% CI −0.09 to 0.004), p=0.07 | Change level: 0.26 (95% CI −0.74 to 1.26), p=0.61 | Change level: 0.16 (95% CI −0.67 to 0.99), p=0.71 | Change level: −0.39 (95% CI −1.09 to 0.30), p=0.27 | Untransformed 1.46 Prais-Winsten 2.02 | |
| Change trend: 0.06 (95% CI 0.004 to 0.12), p=0.04 | Change trend: −0.02 (95% CI −0.05 to 0.01), p=0.24 | Change trend: 0.05 (95% CI 0.03 to 0.07), p<0.01 | ||||
| Percentage TBI admissions neurosurgical* | 0.05 (95% CI −0.01 to 0.11), p=0.10 | Change level: −0.64 (95% CI −1.83 to 0.56), p=0.29 | Change level: 0.47 (95% CI −0.17 to 1.12), p=0.15 | Untransformed 1.81 | ||
| Change trend: −0.06 (95% CI −0.12 to 0.001), p=0.047 | Change trend: −0.01 (95% CI −0.03 to −0.003), p=0.01 | |||||
| Deaths/100 000 | 0.03 (95% CI 0.001 to 0.07), p=0.04 | −0.001 (95% CI−0.004 to 0.002), p=0.57 | Change level: −0.02 (95% CI −0.09 to 0.06), p=0.62 | Change level: −0.01 (95% CI −0.06 to 0.05), p=0.85 | Untransformed 2.3 | |
| Change trend: 0.001 (95% CI−0.002 to 0.005), p=0.44 | Change trend: 0.0004 (95% CI −0.001 to 0.001), p=0.46 | |||||
| Percentage TBI admissions death | 0.88 (95% CI 0.36 to 1.41), p<0.01 | 0.03 (95% CI −0.03 to 0.10), p=0.35 | Change level: −0.79 (95% CI −2.12 to 0.54), p=0.24 | Change level: 0.52 (95% CI −0.32 to 1.35), p=0.22 | Untransformed 2.08 | |
| Change trend: −0.03 (95% CI −0.10 to 0.03), p=0.33 | Change trend: −0.03 (95% CI −0.04 to −0.01), p<0.01 |
*Neurosurgical procedure defined as one or more OPSC4 codes: A05.2, A05.3, A05.4, A05.8, A05.9, A40.1, A40.8, A40.9, A41.1, A41.8, A41.9, V03.1, V03.2, V03.4, V03.6, V03.7, V03.8, V03.9, V05.3 and V05.4.
SIGN, Scottish Intercollegiate Guidelines Network; TBI, traumatic brain injury.