canadian_ct_head_rule: Canadian CT Head Rule

In cliot: Clinical Indices and Outcomes Tools

Canadian CT Head Rule

Description

Applies the Canadian CT Head Rule (CCHR) to determine the need for computed tomography (CT) imaging in patients with minor head injury. It stratifies patients into High Risk (requiring neurological intervention), Medium Risk (risk of brain injury on CT), and Low Risk (CT not indicated). The rule is applicable to patients with GCS 13-15 and loss of consciousness, amnesia, or confusion.

Usage

canadian_ct_head_rule(gcs_less_than_15_at_2h, suspected_open_skull_fracture,
                      basal_skull_fracture_signs, vomiting_ge_2, age,
                      amnesia_pre_impact_gt_30m, dangerous_mechanism)

Arguments

gcs_less_than_15_at_2h	Numeric (0 or 1). Glasgow Coma Scale score < 15 at 2 hours post-injury. (1 = Yes).
suspected_open_skull_fracture	Numeric (0 or 1). Suspected open or depressed skull fracture. (1 = Yes).
basal_skull_fracture_signs	Numeric (0 or 1). Any sign of basal skull fracture (hemotympanum, raccoon eyes, CSF otorrhea/rhinorrhea, Battle's sign). (1 = Yes).
vomiting_ge_2	Numeric (0 or 1). Vomiting >= 2 episodes. (1 = Yes).
age	Numeric. Patient age in years. (>= 65 years is High Risk).
amnesia_pre_impact_gt_30m	Numeric (0 or 1). Retrograde amnesia to the event > 30 minutes. (1 = Yes).
dangerous_mechanism	Numeric (0 or 1). Dangerous mechanism of injury (Pedestrian struck by vehicle, occupant ejected, fall from >3 ft or 5 stairs). (1 = Yes).

Value

A list containing:

Risk_Level	"High Risk", "Medium Risk", or "Low Risk".
Recommendation	"CT Head is indicated" or "CT Head not indicated".
Reasoning	Explanation of the risk based on intervention need or injury findings.

References

Stiell IG, Wells GA, Vandemheen K, et al. The Canadian CT Head Rule for patients with minor head injury. Lancet. 2001;357(9266):1391-1396. doi:10.1016/s0140-6736(00)04561-x

Examples

# Example 1: High Risk (Age)
# 70yo, no other symptoms
canadian_ct_head_rule(0, 0, 0, 0, 70, 0, 0)

# Example 2: Medium Risk (Dangerous Mechanism)
# 30yo, Fall from >3ft, GCS 15
canadian_ct_head_rule(0, 0, 0, 0, 30, 0, 1)

# Example 3: Low Risk
# 25yo, Minor fall, no amnesia/vomiting
canadian_ct_head_rule(0, 0, 0, 0, 25, 0, 0)

cliot documentation built on Dec. 1, 2025, 1:06 a.m.