To evaluate the usefulness of admission and daily acute physiology and chronic health evaluation (APACHE) III score in relation to length of stay in the intensive care unit (ICU) for outcome prediction, 4,554 patients were studied.

These patients were admitted to the ICU from June 6, 1994 to December 31, 2002. Exclusion criteria included patients being treated for burns, having surgery for coronary artery bypass grafts, having a diagnosis of myocardial infarction, being under 16 years of age and being discharged less than 16 hours after admission. To evaluate the discrimination power of admission and daily APACHE III score, the area under the receiver operating characteristic curve was computed for each of the initial 16 days of ICU care.

Admission APACHE III score loses discrimination power over time, from admission day to day 4 in the ICU, the area under the receiver operating characteristic curve was above 0.8 and after day 16, it dropped to below 0.7. However, daily APACHE III score maintained discrimination power at about 0.8 over time.

In the early days after ICU admission, admission and daily APACHE III score are useful. With time daily APACHE III scores are more useful than admission APACHE III score.