Development and initial validation of the localized scleroderma skin damage index and physician global assessment of disease damage: a proof-of-concept study

Abstract

Objective: To develop and assess the psychometric properties of the Localized Scleroderma (LS) Skin Damage Index (LoSDI) and Physician Global Assessment of disease Damage (PGA-D).

Methods: Damage was defined as irreversible/persistent changes (>6 months) due to previous active disease/complications of therapy. Eight rheumatologists assessed the importance of 17 variables in formulating the PGA-D/LoSDI. LS patients were evaluated by two rheumatologists using both tools to assess their psychometric properties. LoSDI was calculated by summing three scores for cutaneous features of damage [dermal atrophy (DAT), subcutaneous atrophy (SAT) and dyspigmentation (DP)] measured at 18 anatomic sites. Patient GA of disease severity (PtGA-S), Children's Dermatology Life Quality Index (CDLQI) and PGA-D were recorded at the time of each examination.

Results: Thirty LS patients (112 lesions) and nine patient-visit pairs (18 lesions) were included for inter- and intra-rater reliability study. LoSDI and its domains DAT, SAT, DP and PGA-D demonstrated excellent inter- and intra-rater reliability (reliability coefficients 0.86-0.99 and 0.74-0.96, respectively). LoSDI correlated moderately with PGA-D and poorly with PtGA-S and CDLQI. PGA-D correlated moderately with PtGA-S, but poorly with CDLQI.

Conclusions: To complete the LS Cutaneous Assessment Tool (LoSCAT), we developed and evaluated the psychometric properties of the LoSDI and PGA-D in addition to the LS Skin Severity Index (LoSSI). These instruments will facilitate evaluation of LS patients for individual patient management and clinical trials. LoSDI and PGA-D demonstrated excellent reliability and high validity. LoSCAT provides an improved understanding of LS natural history. Further study in a larger group of patients is needed to confirm these preliminary findings.

Fig. 1

Localized Scleroderma Skin Damage domains distribution. Bars represent the frequencies of each domain score. Distribution recorded by two raters (A and B) from 112 cutaneous surface anatomic sites examined.

Fig. 2

LoSDI distribution. Bars represent LoSDI scores recorded by two raters (A and B) from 39 patient-visits.

Fig. 3

Scatter plot showing the correlation between the LoSDI and PGA-D. Spearman's correlation coefficient = 0.58 (P < 0.001).

Fig. 4

LoSCAT.