ICU Scoring Systems

22nd June 2007

Ulster Hospital

Gail Browne

ICU Scoring Systems

• Why are scoring systems needed?

• Classifying scoring systems

• History of scoring systems

• Examples of scoring systems

• Recent developments

• Selecting a scoring system

• Discussion

“It’s more important to know what sort of person this

disease has, than what sort of disease this person has.”

William Osler 1849-1919

Why are scoring systems needed?

• Scoring systems can provide:

- Case-mix adjustment for evaluative research- A tool for comparative audit - SMR- A mechanism to decide resource allocation- An aid for the clinical management of patients

Scoring Systems

• Specific or generic• Anatomical or physiological• Anatomical systems – assess extent of injury

(eg injury severity score)• Physiological systems – assess impact of

injury on function (eg GCS)

First Scoring Systems

• Developed for trauma pts• Specific anatomical methods:

- abbreviated injury score 1969- Burns score 1971- Injury severity score 1974

• Specific physiological methods:- trauma index 1971- Glasgow coma scale 1974- Trauma score 1981- Sepsis score 1983

Scoring Systems

• Later scoring systems generic• Measuring severity by treatment – TISS

(Therapeutic Intervention Scoring System) 1974

• Measuring severity of organ dysfunction based on type & amount of tx received

• Measuring severity by patient characteristics & physiological measurements - SAPS, APACHE, MPM

Scoring System Development

• Pt variables that influence survival collected by consensus or statistical analysis

• Scoring model developed from large cohort & validated on another cohort

Classifying Scoring SystemsGeneral Scores Specialised &

Surgical Intensive Care – Preop evaluation

Trauma Scores

Therapeutic Intervention Nursing Scores

• SAPS II expanded & predicted mortality• APACHE II & predicted mortality• SOFA (Sequential Organ Failure Assessment)• MODS (Multiple Organ Dysfunction Score)• ODIN (Organ Dysfunctions &/or Infection)• MPM (Mortality Probability Model)• LODS (Logistic Organ Dysfunction System)• TRIOS (Three days recalibrated ICU outcome Score)

• Lung resection score

• EUROSCORE

• ONTARIO

• Parsonnet score

• System 97 score

• QMMI score

• POSSUM (physiologic & operative severity score for the enUmeration of mortality & morbidity)

• IRISS score

• GCS

• ISS (Injury Severity Score)

• RTS (revised trauma score)

• TRISS (trauma injury severity score)

• ASCOT (a severity characterization of trauma)

• 24h – ICU Trauma Score

• TISS (therapeutic intervention scoring system)

• TISS – 28 (simplified TISS)

History

• 1953 – Virginia Apgar• 1974 – Glasgow Coma Scale

• Quantifying relationship between disease severity and outcome

• 1980s – acute physiology and chronic health evaluation (APACHE) & simplified acute physiological score (SAPS)

History• APACHE & SAPS – physiologically based

classification systems• General severity scores• Aim at stratifying patients based on their severity• 1985 – 1993: general outcome prediction models• 1991 – APACHE III• 1993 – SAPS II• 2005 – SAPS III (www.saps3.org)• 2006 – APACHE IV• During process of evolution of models, main

prognostic determinants of outcome changed

APACHE

• William Knaus• Initially 34 physiological variables• 1985 – APACHE II 12 variables• APACHE II allows probability of death before

hospital discharge to be estimated• Standardised mortality ratio

APACHE II score = (acute physiology score) + (age points) + (chronic health points)

Scores range from 0 – 71 Score risk of hospital death

SAPS (Simplified Acute Physiology Score)

• Le Gall reduced former 34-variable APACHE score to 14 parameters

SOFA (Sequential Organ Failure Assessment) Score

MPM (Mortality Prediction Models)

• Developed by Stanley Lemeshow• Uses data collected during first hour of ICU

admission; 24 hours; 72 hours• Series of true/false questions• Weighted according to their individual

contribution to mortality

TISS (Therapeutic Intervention Scoring System)

• Measuring sickness severity based on type & amount of treatment received

• Both clinical & administrative applications:- assessing severity of illness- Determining resource requirements- Assessing use of critical care facilities & function– Not standardised

• Daily data collected from each pt on 76 possible clinical interventions

TISS (Therapeutic Intervention Scoring System)

• Four classes of pt recognised:- Class I < 10 points does not require ICU- Class II 10-19 points 1:2 nurse:pt ratio- Class III 20-39 points 1 ICU nurse- Class IV > 40 points 1:1 nurse:pt ratio++

Other Scoring Systems…

CPIS (Clinical Pulmonary Infection) Score

Early Warning Physiological Scoring Systems

• MERIT study• SOCCER study• The Worthing physiological scoring system –

BJA June 2007

The Worthing PSS

0 1 2 3

Ventilatory Frequency

19 20-21 22

Pulse 101 102

SBP 100 99

Temp 35.3 < 35.3

Oxygen Sat in air

96 - 100 94 - <96 92 - < 94 < 92

AVPU Alert Other

(Duckitt et al, 2007)2,3,4 – be alert!

5 urgent doctor review

Recent developments - New Models

• SAPS III admission model – chronic health & circumstances of ICU admission now responsible for approx. ¾ prognostic power of model.

• APACHE IV Model – Jack Zimmerman• MPM III Model• ICNARC Model

Selecting a Scoring System

• Depends on proposed use• Validity• Reliability• Calibration • Discrimination• Outcome from ICU…?• Other scoring systems eg sedation scores,

sepsis bundles,CPIS, early warning physiological scoring systems, POSSUM…..

Discussion…