Preliminary Validation of the Digital Ulcer Clinical Assessment Score in Systemic Sclerosis

Objective. To date, "healed/non-healed" and clinical judgment are the only available assessment tools for digital ulcers (DU) in patients with systemic sclerosis (SSc). The aim of our study is to examine a preliminary composite DU clinical assessment score (DUCAS) for SSc for face, content, and construct validity. Methods. Patients with SSc presenting at least 1 finger DU were enrolled and assessed with the Health Assessment Questionnaire-Disability Index, Cochin scale, visual analog scale (VAS) for DU-related pain, patient global DU status, and global assessment as patient-reported outcomes (PRO), and physician VAS for DU status (phyGDU) as an SSc-DU expert physician/nurse measure. The DUCAS included 7 DU-related variables selected by a committee of SSc DU experts and weighted on a clinical basis. Face validity was examined by consensus and partial construct validity was tested through convergent correlation with other measures of hand function, using Spearman's correlations. A range of patients with SSc was examined. A linear regression model with backward stepwise analysis was used to determine the relationship of individual variables with the primary clinical parameter, phyGDU. Results. Forty-four patients with SSc (9 males, mean age 55 +/- 15 yrs, mean disease duration 9.9 +/- 5.8 yrs) were enrolled in the study. Overall DUCAS showed significant positive correlations with all abovementioned PRO (r > 0.4, p < 0.01). When all scores and scales were modeled, only DUCAS significantly predicted phyGDU (r = 0.59, R-2 = 0.354, Akaike information criterion = 385.4). Conclusion. Preliminarily, we suggest that the DUCAS may be a new clinical score for SSc-related DU, having face and content validity and convergent/divergent correlations (construct validity). These early data suggest that this score deserves further evaluation.