Outcome measures of disease severity in atopic eczema

Background: An essential component of evidence-based medicine is the use of valid and reliable outcome measures in clinical trials. There is much confusion in the field of atopic eczema regarding how to best measure disease severity objectively. Objective: To establish the extent to which existing objective clinical scales for atopic eczema have been tested for validity, reliability, sensitivity to change, and acceptability. Design: An electronic bibliographic search was performed for published data on all currently available named atopic eczema scales. Results: Thirteen scales were identified in total. Data on construct or criterion validity were available for 10 scales. Only 5 scales had been tested for reliability (interobserver variability, intraobserver variability, or internal consistency). Data on responsiveness to change were available for 8 scales. An estimated time to administer the measure had been given for 3 scales. The only severity scale for which published data could be found on validity, reliability, sensitivity, and acceptability testing was the Severity Scoring of Atopic Dermatitis index, although problems occurred with interobserver variation of the index. Conclusion: The rapidly increasing number of severity scales for atopic eczema, many of which have been inadequately tested, has made the interpretation of patient out comes confusing, and comparison of results between studies almost impossible. Consensus among clinicians and researchers on the use of severity scales for atopic eczema should be based on evidence of adequate validity, reliability, sensitivity to change, and ease of use.