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Development of the CLASI as a Tool to Measure Disease Severity and Responsiveness to Therapy in Cutaneous Lupus Erythematosus


Development of the CLASI as a Tool to Measure Disease Severity and Responsiveness to Therapy in Cutaneous Lupus Erythematosus

Rachel Klein et al. Arch Dermatol.


Objective: To determine how to use the Cutaneous Lupus Erythematosus Disease Area and Severity Index (CLASI) to classify patients according to disease severity (mild, moderate, and severe) and to identify which patients respond to therapy.

Design: Cohort.

Setting: The connective-tissue disease clinic at the Hospital of the University of Pennsylvania, Philadelphia.

Patients: Seventy-five patients with clinical or histopathologic evidence of cutaneous lupus erythematosus or systemic lupus erythematosus were included in the study.

Main outcome measures: The CLASI, Skindex-29, and the physician's subjective assessment of severity and improvement were completed at every visit.

Results: Disease severity was assessed with 45 patient visits. Mild, moderate, and severe disease corresponded with CLASI activity score ranges of 0 to 9, 10 to 20, and 21 to 70, respectively. Improvement in disease activity was assessed in 74 patients. A clinical improvement was associated with a mean 3-point or 18% decrease in the CLASI activity score. However, receiver operating characteristic analysis demonstrated an increased percentage of patients correctly classified when a 4-point (sensitivity, 39%; specificity, 93%; correctly classified, 76%) or 20% (sensitivity, 46%; specificity, 78%; correctly classified, 67%) decrease in the CLASI activity score was used instead to identify improvement.

Conclusion: The CLASI can be used to classify patients into groups according to disease severity and to identify clinically significant improvements in disease activity.

Conflict of interest statement

Financial Disclosures: None reported. The authors report no conflicts of interest.


Figure 1
Figure 1. The CLASI
The Cutaneous Lupus Erythematosus Disease Area an Severity index. Reprinted by permission for the University of Pennsylvania, copyright 2009.
Figure 2
Figure 2. CLASI scores according to disease severity
For a given range of CLASI scores, the percentage of patients within each category of disease severity was calculated.
Figure 3
Figure 3. Quality of life and disease severity
Skindex-29 scores were calculated for each subject at the initial visit. Subjects were divided into severity groups based on CLASI scores. Skindex-29 sub-scores increased with worsening disease severity, indicating strong convergent validity between the CLASI severity classifications and quality of life measures.

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