Injury Severity Score (ISS)

Why Use

Due to the heterogeneous nature of trauma patients, standardizing severity of traumatic injury allows for much larger sample populations in trauma research studies.

When to Use

The ISS is a score that attempts to standardize the severity of injuries sustained during a trauma. This standardization allows one to more accurately study and predict morbidity and mortality outcomes after traumatic injuries.

Formula

Pearls / Pitfalls

Initially derived in patients with blunt traumatic injury from motor vehicle accidents only. The ISS is not intended to be used for bedside decisions regarding a single patient in the emergency department setting, but rather as a tool to standardize the study of trauma patients. Due to the nature of the score, multiple combinations of Abbreviated Injury Scale (AIS) scores may arrive at the same ISS, each of which may indicate a different mortality rate. For example, an ISS of 17 can be made from patients with a combination of points based on the three most severe injuries, such as (4, 1, 0) or (3, 2, 2). The ISS also gives equal importance to each body region. Patients with an AIS of 6 in any body system are automatically assigned an ISS of 75, the maximum possible score.

Management

In all trauma patients, initial treatment strategy should focus on the primary and secondary survey, and assessing and stabilizing the patient. This score is intended mostly for research purposes but may have broader clinical use in the ICU for prognostication following initial stabilization of traumatic injuries.

Advice

As the ISS is intended as more of a research tool, calculation of the ISS should not affect initial management of the patient with traumatic injuries.