Conflicts of interest None declared.
Comparison of the reliability and validity of outcome instruments for cutaneous dermatomyositis
Article first published online: 4 JUL 2008
© 2008 The Authors. Journal Compilation © 2008 British Association of Dermatologists
British Journal of Dermatology
Volume 159, Issue 4, pages 887–894, October 2008
How to Cite
Klein, R.Q., Bangert, C.A., Costner, M., Connolly, M.K., Tanikawa, A., Okawa, J., Rose, M., Fakharzadeh, S.S., Fiorentino, D., Lee, L.A., Sontheimer, R.D., Taylor, L., Troxel, A.B. and Werth, V.P. (2008), Comparison of the reliability and validity of outcome instruments for cutaneous dermatomyositis. British Journal of Dermatology, 159: 887–894. doi: 10.1111/j.1365-2133.2008.08711.x
The sample questionnaires are available as supplementary appendices with the online version of this article.
- Issue published online: 17 SEP 2008
- Article first published online: 4 JUL 2008
- Accepted for publication 31 March 2008
- outcome instrument;
- severity index
Background Reliable and validated measures of skin disease severity are needed for cutaneous dermatomyositis (DM). Cutaneous Dermatomyositis Disease Area and Severity Index (CDASI), Dermatomyositis Skin Severity Index (DSSI) and Cutaneous Assessment Tool (CAT) skin indices have been developed as outcome instruments.
Objectives We sought to demonstrate reliability and validity of the CDASI, and to compare the CDASI with other potential tools for use in measuring disease severity in cutaneous dermatomyositis.
Patients and methods CDASI has four activity and two damage measures, with scores from 0 to 148. DSSI assesses activity based on body surface area and severity on a scale of 0–72. CAT uses 21 activity and damage items, for a range of 0–175 for activity and 0–33 for damage. Ten dermatologists used the instruments to score the same 12–16 patients in one session. Global validation measures were administered to physicians and patients.
Results Global validation measures correlated with the three outcome instruments (P < 0·0001). CAT displayed lower inter- and intrarater reliability relative to the CDASI. All scales correlate better with physician than patient global skin measures.
Conclusions It appears that the CDASI may be a useful outcome measure for studies of cutaneous DM. Further testing to compare responsiveness of all three measures is necessary.