Accident Severity Accident Severity

Collision severity

Injury severity

Early Severity Scales

Burden of injury – live or dead Live - bleeding or not bleeding Injured – treated or not treated Treated – physician, doctor’s office emergency room released or admitted Injury Severity Department of Transport Fatal Injury - which caused death in less than 30 days after the accident. Serious Injury - inpatient or fracture, concussion, internal injuries, crushings, severe cuts, severe shock type of injury or death after 30 days. Slight Injury - minor sprain, bruise, cut, or requiring only roadside attention WORKING DEFINITIONS OF A FATALITY Greece, Portugal, Spain use within 24 hours. France uses within 6 days. Italy uses within 7 days. Most other states use within 30 days.

Correction Factors applied to get 30 day equivalent, range from 1.3 (Spain) to 1.078 (Italy).

Serious & Slight

Prone to error severity assessed and assigned by police at the scene

Correct in ≈ 60% of cases Therefore a better scale is needed which could be used by non medics and the scale that is anatomically based

Developed in the 1960’s by a group of 75 specialists from around the world.

Introduced in 1971

Revised in 1980, 1985, 1990,1998 & 2005 Abbreviated Injury Scale

Probability of threat to life scale based on individual injury 7 digit code used to classify an injury. 123456.7 The code describes type of injury location of injury severity of injury

Abbreviated Injury Scale 123456.7

1 Body Region 2 Type of Anatomical Structure 3/4 Specific Anatomical Structure 5/6 Level 7 Severity Score 1 Body Region 123456.7

1 Head 6 Spine 2 Face 7 Upper Extremity 3 Neck 8 Lower Extremity 4 9 Unspecified 5 Abdomen 2 Type of Anatomic Structure 123456.7 1 Whole Area 2 Vessels 3 Nerves 4 Organs (inc. muscles/ligaments) 5 Skeletal (inc. joints) 6 Loss of Consciousness (head only) 3/4 Specific Anatomic Structure 123456.7 Whole Area Head - Loss of Consciousness (LOC) 02 Skin Abrasion 02 Length of LOC 04 Contusion 04-08 Level of Consciousness 06 Laceration 10 Concussion 08 Avulsion 10 Amputation Spine 20 02 Cervical 30 Crush 04 Thoracic 40 06 Lumbar 50 Injury - NFS 60 Penetrating Vessels, Nerves, Organs, Bones, Joints These are all assigned consecutive two digit numbers beginning with 02 5/6 Level 123456.7

Specific Injuries are assigned consecutive two-digit numbers beginning with 02 Fractures, rupture, laceration, etc Injury Severity Abbreviated Injury Score 1 Minor 2 Moderate 3 Serious 4 Severe 5 Critical 6 Maximum AIS

AIS Example 1 superficial laceration 2 fractured sternum 3 open fracture of humerus 4 perforated trachea 5 ruptured liver with tissue loss 6 total severance of aorta

AIS – Threat to life

AIS % prob. of death 1 0 2 1 – 2 3 8 – 10 4 - 5 50 – 50 6 100

Organ injuries Skeletal injuries Measures of Injury Severity

• Maximum Abbreviated Injury Score (MAIS) - Maximum AIS for an occupant or body region - Frequently used for assessing overall severity - Non-linear relationship with the probability of death

Body region AIS MAIS Head 4 Neck 2 Thorax 5 5 Abdomen 1 Lower limb 3

Injury Severity Score (ISS)

Gives a better fit between overall severity & probability of survival than MAIS

The ISS is the sum of the squares of the highest AIS code in each of the three most severely injured ISS body regions.

There six ISS body regions.

Six ISS body regions Head or Neck Face Thorax Abdominal or Pelvic content Extremities or Pelvic Girdle External (ISS)

Body region AIS MAIS Head 4 Neck 2 Thorax 5 5 Abdomen 1 Lower limb 3 ISS = (5x5)+(4x4)+(3x3) = 50 ISS range 0 – 75 Proviso : AIS 6 = ISS 75 Linear scale 0 - 75

Examples

Uses of Injury Severity Data • Eppinger et al (1999) (NHTSA)

• Foret-bruno et al (1998) 42nd STAPP • Mertz (1971??)