Severity of a case for outcome assessment in health care--definitions and classification of instruments.

Severity of a case is one of the ingredients in management systems. Severity adjustment systems have limitations, and confusion and diversity characterize definitions of severity of a case. These facts may be a consequence of lack of conceptual knowledge. Based on a holistic theory of health, we introduce a definition of severity of a case from a patient perspective. Here severity is characterized as having two basic components: disease severity and illness severity; and five dimensions: suffering, disabilities, risk of suffering, risk of disabilities and risk of death. A classification of instruments as measures of severity dimensions is presented. This classification is based on definition and application criteria. The article's main contribution is to combine theoretical and practical knowledge about severity of a case, which may empower implementations of outcome management systems in health care.