Quality of patient care-a measurement of change: the staging concept.

A method that can be used to classify the severity of health problems and measure change in health status is described. The "staging" concept provides a system which classifies patients with similar medical conditions into clusters useful for patient care evaluation. The method defines different levels of severity: Stage I-disease with no complications or problem of minimal severity; Stage II-disease with local complications or problem of moderate severity; and Stage III-disease with systemic complications or a problem of a serious nature. Examples of the method are given and the value of the approach is described for the evaluation of the hospitalized and ambulatory patient.