Percentage of model variance attributable to factors used to predict intensive care unit length of stay remaining after day 5. Physiology refers to the acute physiology score (APS) and rescaled Glasgow Coma Score. Rescaled PaO2/FiO2 ratio is defined in Appendix Table 1. GCS unable refers to inability to assess Glasgow Coma score due to sedation or paralysis. Diagnostic category includes 57 mutually exclusive diagnostic groups on day 5. Miscellaneous includes age, prior length of stay, emergency surgery, and ICU readmission.