Evaluating the cutaneous involvement in scleroderma: torsional stiffness revisited

Objective. The pace, progression and extent of the skin lesions in sclerode rma may parallel the risk of new internal organ involvement and the progres sion 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 stiffne ss for its ability to measure sclerodermatous skin in a quantitative and re producible manner. Materials and methods. Torsional skin stiffness was measured in 56 normal s ubjects and 42 scleroderma patients (31 of whom had the limited form and ni ne the diffuse form, and two had mixed connective tissue disease). Data for the scleroderma patients were compared with data obtained by the use of th e modified Rodnan clinical skin scoring technique. Intraclass correlation c oefficients (ICCs) were calculated as a measure of intraobserver and intero bserver variability. Results. For the left and right hands respectively, the ICCs for intraobser ver variability were 0.908 and 0.906 and those for interobserver variabilit y 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 a ngular 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 h ighly reproducible and are consistent with the current clinical method of a ssessment of skin involvement. The significant difference in angular rotati on obtained by normal subjects and scleroderma patients indicates that the device can distinguish normal from sclerodermatous skin. The torsional stif fness measurements derived from the device may also be useful in longitudin al studies.