Assessment of area of involvement in skin disease: a study using schematic figure outlines.

The ability to assess the severity of dermatoses by measurement of area of involvement is important in both clinical practice and research. Using schematic figure outlines we have shown that physicians, nurses and other groups are unable to assess area accurately, and that the degree of error is partially dependent on absolute area, but also on other factors. The pattern and magnitude of the errors varied between the groups examined, but overall was such that it calls in question the use of area indices such as the PASI (psoriasis area and severity index) score in the assessment of inflammatory dermatoses.