| Variable | Conceptual definition | Operational definition | Source |
| Mortality | Death of the patient during a stay in the emergency department or intensive care unit | Death of the patient during a hospital stay | Instrument |
| Sex | A set of biological conditions that characterize each person as either male or female. | Biological sex obtained from the medical record | Instrument Clinical record |
| Age | How long a person has lived since birth in whole years | Age obtained from the medical record | Instrument Clinical record |
| Cause of Trauma | Event That Causes Traumatic Brain Injury | Cause obtained from the medical record | Instrument Clinical record |
| Anisocoria | Asymmetry in pupillary size | Asymmetrical pupillary size | Instrument Clinical record |
| Midriasis | Bilateral reactive pupillary dilation greater than 4 mm | Recorded reactive pupillary dilation | Instrument Clinical record |
| Seizures | Transient and involuntary episodes of impaired consciousness, behavior, or motor activity | Episode of seizures on admission recorded | Instrument Clinical record |
| Hyperglycaemia | Blood glucose greater than 180 mg/dL on admission | Baseline hyperglycemia recording | Instrument Clinical record |
| Hypoglycemia | Glucemia less than 80 mg/dL on admission | Baseline hypoglycemia recording | Instrument Clinical record |
| Hemoglobin | Optimal hemoglobin levels 7 - 9 g/dL | Basal hemoglobin recording | Instrument Clinical record |
| Hypernatremia | Plasma sodium levels greater than 155 mEq/L | Recording of sodium levels above reference values | Instrument Clinical record |
| Hyponatremia | Plasma sodium levels less than 135 mEq/L | Recording of sodium levels above reference values | Instrument Clinical record |
| Hyperthermia | Body temperature greater than 38˚C | Recording of sodium levels above reference values | Instrument Clinical record |
| Hypotension | Systolic blood pressure less than 90 mmHg on admission | Baseline hypotension recording | Instrument Clinical record |