“…20,21 Proprietary software from 3M (all patient refined-diagnosis-related group grouper, version 24) was applied to every record to generate a severity of illness level and a risk of mortality level at the time of admission. 22,23 Software categorized each of these parameters as mild, moderate, major, or extreme. Hospital characteristics were specified on the basis of size (<100, 101-200, >200 beds), type (private, Kaiser affiliated, academic), location (rural or urban), and kind (profit, not for profit).…”