Revised Trauma Score (RTS) Calculator — Survival Probability Estimator

What Is the Revised Trauma Score (RTS)?

The Revised Trauma Score (RTS) is a physiological scoring system developed by Champion and associates to assess the severity of trauma and estimate survival probability. It uses only three readily available clinical measurements that are assessed in every emergency patient, making it practical for use in any acute care setting.

The Pathophysiology of Trauma

Major trauma is an injury that may lead to death or permanent disability and is one of the leading causes of death worldwide according to the WHO. Regardless of the mechanism (blunt, penetrating, or burns), severe trauma triggers a cascade of pathophysiological changes:

• Decreased organ perfusion due to blood loss or shock
• Cellular ischemia leading to tissue damage
• Systemic inflammatory response (SIRS)
• Altered mental status from brain injury or poor perfusion
• Respiratory compromise from chest injury or central nervous system depression

The more severe the trauma, the more pronounced these pathophysiological changes — and the lower the RTS score.

Why Use the Revised Trauma Score?

Trauma scoring systems standardize communication about injury severity and guide decision-making in individual patients. The RTS:

• Provides a single numerical value reflecting physiological derangement
• Helps triage patients in mass casualty events
• Guides transport decisions (local hospital vs. trauma center)
• Enables research comparisons across institutions and time periods
• Forms part of the TRISS methodology for survival probability prediction

How to Calculate the RTS

The RTS is derived from three coded physiological parameters:

Glasgow Coma Scale (GCS)

The GCS measures neurological status (score 3–15):

• Eyes (1–4): Spontaneous, to voice, to pain, none
• Verbal (1–5): Oriented, confused, words, sounds, none
• Motor (1–6): Obeys commands, localizes, withdraws, abnormal flexion, extension, none

Systolic Blood Pressure (SBP)

Measured in mmHg — the same unit used universally in both American and metric medical practice. SBP reflects circulatory status and hemorrhagic shock severity.

Respiratory Rate (RR)

Measured in breaths per minute. Normal RR is 12–20/min. Both very low and very high rates indicate physiological compromise.

Coding Table

The RTS Formula

The RTS is calculated as a weighted sum:

RTS = 0.9368 × GCS_coded + 0.7326 × SBP_coded + 0.2908 × RR_coded

Maximum RTS = 0.9368 × 4 + 0.7326 × 4 + 0.2908 × 4 = 7.8408

The weights reflect the relative prognostic importance of each parameter. GCS carries the highest weight, emphasizing the critical role of neurological status in trauma outcome.

Survival Probability

Based on the RTS, survival probability (Ps) can be estimated using logistic regression:

Ps = 1 / (1 + e^−b), where b = RTS − 1.2470

This formula provides an estimate of the probability of survival based solely on physiological measurements at presentation.

RTS Interpretation

• RTS 7.00–7.84: Minor physiological derangement — excellent prognosis
• RTS 5.00–6.99: Moderate derangement — good prognosis with appropriate care
• RTS 3.00–4.99: Serious derangement — requires immediate intensive care
• RTS 0–2.99: Critical derangement — poor prognosis, maximal intervention required

Clinical Example

A trauma patient presents with:

• GCS = 14 (coded as 4, since 13–15 → 4)
• SBP = 85 mmHg (coded as 3, since 76–89 → 3)
• RR = 22/min (coded as 4, since 10–29 → 4)

RTS = 0.9368 × 4 + 0.7326 × 3 + 0.2908 × 4 = 3.7472 + 2.1978 + 1.1632 = 7.1082

Survival probability ≈ 1 / (1 + e^{−(7.1082 − 1.247)}) ≈ 99.7%

Limitations of the RTS

• The RTS reflects physiological status at one point in time; trends over time are more informative
• Does not account for anatomical injury severity (for that, use the Injury Severity Score — ISS)
• Full survival probability prediction uses TRISS (RTS + ISS + age)
• GCS assessment may be unreliable in intubated or sedated patients
• Should not replace clinical judgment or a thorough physical examination