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Reliability testing of the Six Area, Six Sign Atopic Dermatitis severity score
C R Charman1, A J Venn, H C Williams
1Department of Dermatology, Queen's Medical Centre, Nottingham NG7 2UH, UK. carolyn.charman@nottingham.ac.uk
Background:
The Six Area, Six Sign Atopic Dermatitis (SASSAD) severity score is an objective atopic eczema severity index designed principally to assess response to treatment in therapeutic trials. Validity has been demonstrated in single and multicentre clinical trials, although data on the reliability of the index have not previously been published.
Objectives:
To assess inter- and intraobserver variability of the SASSAD index.
Methods:
Six observers with experience in the assessment of atopic eczema were each asked to score disease severity in six patients with moderate to severe atopic eczema using the SASSAD index. Repeat observations were carried out on randomly selected patients by each observer to estimate intraobserver variation.
Results:
The interobserver variation in total SASSAD scores for each patient ranged from 7 to 30 (median 15.5) out of a maximum possible score of 108. The intraclass correlation coefficient ri for the total scores among all six observers was quite high at 0.70, although interobserver agreement for individual components of the index was poor to moderate. The maximum recorded intraobserver variation in total SASSAD score in any of the examined patients was 8 units.
Conclusions:
As with many other tested atopic eczema scoring indices, the SASSAD index is subject to significant interobserver variation, reflecting the difficulties in reliably assessing eczema severity objectively.