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Updated: Jul 9, 2026
Measuring Psoriasis Severity at Home
Published on: March 1, 2024
Development and validation of a comprehensive acne severity scale
Jerry K L Tan1, Jing Tang, Karen Fung
1University of Western Ontario, London, ON, Canada. jerrytan@bellnet.ca
Background:
Although more than 25 acne grading systems exist, only 2 are inclusive of truncal acne. There is neither a gold standard nor a consistently used standardized system.
Purpose:
Our purpose was to develop and validate an acne grading system incorporating severity at the face, chest, and back.
Methods:
We developed a comprehensive acne severity scale (CASS) by modifying a preexisting facial acne scale, the Investigator Global Assessment, to include truncal acne. The validity and responsiveness of CASS grades were correlated with Leeds scores at baseline and after 6 months of standard acne treatment.
Results:
Spearman correlations were significant between Leeds and CASS grades for the face (0.823), chest (0.854), and back (0.872), respectively (p < .001). After 6 months of therapy, changes in these scores were also significantly correlated (p < .001) at all three sites.
Conclusion:
Concurrent validity of CASS is demonstrated by a very strong correlation with Leeds grading. CASS is simpler to use than the Leeds system and more appropriate for translation of research trial results to clinical practice.
