Objective: The pace, progression and extent of the skin lesions in scleroderma may parallel the risk of new internal organ involvement and the progression of existing internal lesions. Accurate assessment of cutaneous change permits an evaluation of patient prognosis and the response to therapy. The aim of this study was to assess a simple device for measuring skin stiffness for its ability to measure sclerodermatous skin in a quantitative and reproducible manner. Materials and methods. Torsional skin stiffness was measured in 56 normal subjects and 42 scleroderma patients (31 of whom had the limited form and nine the diffuse form, and two had mixed connective tissue disease). Data for the scleroderma patients were compared with data obtained by the use of the modified Rodnan clinical skin scoring technique. Intraclass correlation coefficients (ICCs) were calculated as a measure of intraobserver and interobserver variability.
Results: For the left and right hands respectively, the ICCs for intraobserver variability were 0.908 and 0.906 and those for interobserver variability were 0.871 and 0.628. There was a significant difference in mean angular rotation obtained by normal subjects compared with scleroderma patients (15.1 vs 11.3 degrees, P<0.001). There was a significant difference in the angular rotation with increasing severity of skin involvement (skin score 0, median rotation 16.3 degrees; score 1, 10.5 degrees; score 2, 8.5 degrees; score 3, 8.0 degrees; P<0.00001).
Conclusions: The measurements obtained with the skin stiffness device are highly reproducible and are consistent with the current clinical method of assessment of skin involvement. The significant difference in angular rotation obtained by normal subjects and scleroderma patients indicates that the device can distinguish normal from sclerodermatous skin. The torsional stiffness measurements derived from the device may also be useful in longitudinal studies.