*2.8.2 The APACHE score*

The intensive care unit (ICU) makes extensive use of the Acute Physiology and Chronic Health Evaluation (APACHE) score as a method of rating patient outcomes. The worst readings within the first 24 hours of ICU admission are used as the usual data to generate the APACHE II score [9]. In APACHE II, the difficulty of using the original APACHE scale led to the development of the APACHE II scale in 1985. It is the scale for disease severity that is most frequently used. The top score is 71, and there are just 17 physiologic variables as opposed to the original's 34. But even using ICU admission data to calculate, it seems like a good alternative [8, 10–12].

**APACHE III**: The APACHE III severity scale, which differs from APACHE II only in the addition of new characteristics, was developed in 1991. The measure was created using information gathered from 17,440 ICU patients. The APACHE III scale's key characteristic is its daily recalculation of anticipated mortality using the most recent clinical data. This has a higher predictive ability compared to the computation based on the first 24 hours after ICU admission [9].

APACHE IV was developed in 2006 using data from 110,588 patients who were admitted to the ICU between the years of 2003 and 2004. APACHE IV more reliably predicts mortality and the length of an ICU admission than APACHE III [13].
