Understanding Changes in Health Status

Is the Floor Phenomenon Merely the Last Step of the Staircase?

Published In: Medical Care, v. 35, no. 1, Jan. 1997, p. 1-15

Posted on RAND.org on January 01, 1997

by David William Baker, Ron D. Hays, Robert H. Brook

This methodologic article provides new insight into changes in health status. The data were obtained from about 1,000 patients completing health status questionnaires at the time of presenting to the emergency department of a public hospital. The findings from this study suggest that the sensitivity of health status measures to change and the meaning of an incremental change in physical health or mental health vary depending on baseline health. This may result from noninterval properties of response options or from patients being at the lowest health state (the floor) of individual questions. If health status measures similar to this are to be used to compare the outcomes of treatment across diseases and for patients in a wide variety of baseline health states, weighting schemes may be needed to account for these effects. This methodologic piece indicates that more work is needed to increase the validity and the meaning of changes in health status scores when the usual types of health status scales are used to assess health status.

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