National Center for Biotechnology Information NCBI NLM MEDLINE clinical review humans pubmed abstract nih national institutes of health national library of medicine prognosis adult Severity of Illness Index* outcome assessment hospital mortality risk assessment benchmarking pmid:17900487 doi:10.1016/j.ccc.2007.05.004 bekele afessa ognjen gajic mark t keegan apache* critical illness / classification* decision support systems intensive care units* / economics intensive care units* / statistics & numerical data multiple organ failure / diagnosis multiple organ failure / mortality health care / methods*