Transcript Severity scoring systems

Severity scoring systems on ICU
Dr James Hayward
Introduction
• What’s the point?
• We use them often.
• They can quantify severity of illness and
predict in hospital mortality for a group of
patients.
Types
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Diagnosis based
– Less useful as many patients with the same underlying diagnosis may have multiple different
organ failures.
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Physiology based
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MAP, HR
FIO2/PaO2, RR
Temp
GCS
U/O
First-day
– APACHE (acute physiology and chronic health evaluation)
– SAPS (simplified acute physiology score)
– MPM (mortality prediction model)
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Serial scoring
– OSF
– SOFA
– MODS
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Objective
Subjective using pre-agreed limits
My ideal system
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Easy to remember
Easy to calculate
Well calibrated
Applicable to all patient populations
Have the ability to predict functional outcome
as well as quality of life after ICU discharge
Testing of model
• Calibration
– If a scoring system for example predicted a
mortality of 0.25 percent, in a group of 100
patients 25 would be expected not to survive
• Discrimination
– Reviews the ability of a scoring system to
discriminates between patients expected to die
and those who are expected to survive.
APACHE – Acute Physiology and
Chronic Health Evaluation
• APACHE 1981
– 34 variables plus a chronic health evaluation
• APACHE II 1985
– Reduction of number of variables to 12
– Measured during first 24hrs of ITU
– Variables weighted, max score of 71
• Over 25 predicts 50% mortality
• Over 35 predicts 80% mortality
• APACHE III 1991
– More complicated statistical fudging
– Altered variables
– Less commonly used than APACHE II
SAPS – Simplified Acute Physiology
Score
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Started in 1984
SAPS I, SAPS II, SAPS III
First 24hrs of admission
12 weighted physiological variables
SOFA – Sepsis Related Organ Failure
Assessment
• Originally devised by European Society of
Intensive Care Medicine to describe the
degree of organ dysfunction in patients with
sepsis.
• Since been validated for use in patients with
organ dysfunction not due to sepsis
• Respiratory, CVS, CNS, Renal, Coag, Liver. Each
weighted 1-4
Other
• MODS (Multiple Organ Dysfunction Score)
– Scoring is performed on a daily basis
– Six systems (0-4)
• MPM (Mortality Prediction Model)
– Calculates probability of in-hospital death
– Data from hospital admission and within first
24hrs ICU.
Conclusion
• So are they useful?
– Not hugely in my view.
• They allow comparison between patients.
– Bed 1 is more likely to die than Bed 2.
• Can be used to compare ICUs performance/progression
• Can be used for study inclusion
• Certain diseases can make a very bad score but have a very good
prognosis
– DKA
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Non linear
Delay in ITU admission will affect score
Should be used very cautiously in prognosticating.
What we really want to know is outcome and morbidity following
ITU discharge.