The New Zealand medical journal
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Comparative Study
Illness severity scoring for Intensive Care at Middlemore Hospital, New Zealand: past and future.
The Acute Physiological and Chronic Health Evaluation (APACHE) II score is a popular illness severity scoring system for intensive care units. Scoring systems such as the APACHE II allow researchers and clinicians to quantify patient illness severity with a greater degree of accuracy and precision, which is critical when evaluating practice patterns and outcomes, both within or between intensive care units. The study aims to: assess changes in APACHE II scores and hospital-standardised mortality ratio at our ICU over a nine year period from 1 January 1997 to 31 December 2005; assess for changes in the performance of the APACHE II scoring system in predicting patient hospital mortality over the same period; and assess for any clinical subgroups in which APACHE II scoring was particularly inaccurate or imprecise. ⋯ This study shows the progressively worse performance of the APACHE II illness severity scoring system over time due to 'model fade'. This is especially so in common diagnostic categories, making this a clinically relevant finding. Future approaches to illness severity scoring should be tested and compared, such as re-estimating coefficients of the APACHE II diagnostic categories or using locally developed ones, moving to later evolutions of the system such as the APACHE III or APACHE IV, or developing novel artificial intelligence approaches.