Table 3.
Results of logistic regression on factors affecting survival and transfer to neurosurgical care among patients with extradural haematoma or subdural haematoma
| Explanatory variables*
|
Exp (B)† (95% CI)
|
P value
|
|---|---|---|
| Dependent variable—survival | ||
| Age | 0.92 (0.89 to 0.94) | <0.001 |
| Respiratory rate | 119.9 (8.5 to 1688) | <0.001 |
| Glasgow coma scale group | <0.001 | |
| Glasgow coma score 3-8 | 0.09 (0.04 to 0.21) | |
| Glasgow coma score 9-12 | 0.83 (0.83 to 0.26) | |
| Size of haematoma: | <0.001 | |
| Not further specified | 9.90 (2.83 to 34.6) | |
| Small | 6.01 (2.33 to 15.5) | |
| Bilateral | 2.13 (0.52 to 8.76) | |
| Neurosurgical transfer | 4.27 (1.77 to 10.3) | <0.001 |
| Log odds constant −3.58 | ||
| Not in final model: | ||
| Type of haematoma | 0.33 (0.10 to 1.11) | 0.06 |
| Pre-existing medical conditions | 0.91 (0.42 to 1.97) | 0.80 |
| Serious extracranial injuries | 0.39 (0.13 to 1.11) | 0.08 |
| Systolic blood pressure | 2.44 (0.47 to 12.7) | 0.29 |
| Goodness of fit of final model | χ2=3.65, df=8, 0.89 | |
| Dependent variable—neurological transfer | ||
| Age | 0.96 (0.95 to 0.97) | <0.001 |
| Serious extracranial injuries | 0.23 (0.12 to 0.42) | <0.001 |
| Size of haematoma: | <0.001 | |
| Not further specified | 0.79 (0.35 to 1.79) | |
| Small | 0.31 (0.16 to 0.60) | |
| Bilateral | 0.92 (0.28 to 3.07) | |
| Respiratory rate | 36.2 (2.82 to 464) | <0.001 |
| Glasgow coma scale group | 0.01 | |
| Glasgow coma score 3-8 | 1.99 (1.11 to 3.55) | |
| Glasgow coma score 9-12 | 2.16 (1.13 to 4.12) | |
| Log odds constant −3.39 | ||
| Not included in final model: | ||
| Type of haematoma | 1.00 (0.59 to 1.68) | 0.99 |
| Pre-existing medical conditions | 0.97 (0.60 to 1.57) | 0.90 |
| Systolic blood pressure | 1.94 (0.42 to 9.05) | 0.39 |
| Goodness of fit of final model | χ2=4.63, df=8, 0.80 | |
Variables are listed in order they entered forward stepwise selection process. Age was entered as continuous variable, respiratory rate was categorised as 1 (values below 10) and 2 (10 or more); Glasgow coma scale group as 1 (Glasgow coma score 3-8), 2 (Glasgow coma score 9-12) and 3 (Glasgow coma score 13-15); haematoma size as 1 (not further specified), 2 (small), 3 (bilateral) and 4 (large); neurosurgical transfer as 0 (no transfer) and 1 (transferred); type of haematoma as 1 (extradural haematoma) and 2 (subdural haematoma); systolic blood pressure as 1 (<90 mm Hg) and 2 (⩾90 mm Hg); serious extracranial injuries as score on abbreviated injury scale ⩾3; and pre-existing medical conditions as 0 (absent) and 1 (present).
Factor by which odds change when independent variable increases by one unit; values >1 indicate that odds increase as explanatory variable increases and values <1 indicate that odds decrease as explanatory variable increases.