It is applied within 24 hours of admission of a patient to an intensive care unit (ICU): an integer score from 0 to 71 is computed based on several measurements; higher scores correspond to more severe disease and a higher risk of death.
[2] APACHE II was designed to measure the severity of disease for adult patients admitted to intensive care units.
[citation needed] The point score is calculated from 12 admission physiologic variables comprising the Acute Physiology Score, the patient's age, and chronic health status: If the patient has a history of severe organ system insufficiency (i.e. liver cirrhosis, portal hypertension, NYHA class IV heart failure, severe respiratory disease, dialysis dependent) or is immunocompromised (i.e. due to chemotherapy, radiation, high dose steroid therapy, or advanced leukemia, lymphoma or AIDS) assign points as follows: The method is optimized for manual calculation, by using integer values and limiting the number of options so that data fits on a single-sheet paper form.
[3] The score was validated on the dataset from 17,440 adult medical/surgical intensive care unit (ICU) admissions at 40 US hospitals.
The prognostic system of APACHE III has two options: When possible, the time between the patient's arrival at the hospital and their ICU admission is recorded.