Burden of illness score for elderly persons: risk adjustment incorporating the cumulative impact of diseases, physiologic abnormalities, and functional impairments.

To develop and validate a new risk adjustment index-the Burden of Illness Score for Elderly Persons (BISEP)-which integrates multiple domains, including diseases, physiologic abnormalities, and functional impairments. RESEARCH DESIGN SUBJECTS: The index was developed in a prospective cohort of 525 patients aged > or = 70 years from the medicine service of a university hospital. The index was validated in a cohort of 1246 patients aged > or = 65...