Quantification of cutaneous sclerosis with a skin elasticity meter in patients with generalized scleroderma Dory N. H. Enomoto, MD, a Jan R. Mekkes, 1VID, a Patrick M. M. Bossuyt, PhD, b Rick Hoekzema, MD, PhD, a and Jan D. Bos, MD, PhD a Amsterdam, The Netherlands Background: The skin score, a subjective assessment of skin elasticity, is widely used in pa- tients with systemic sclerosis. Although this scoring method is regarded as a validated and accepted tool, the interobserver and intraobserver reproducibility is relatively poor. Objective: Our purpose was to investigate whether the recently developed SEM 474 cutom- eter, which exerts a controlled vacuum force to the skin, can measure skin elasticity more ob- jectively than the skin score. Methods: Skin elasticity was measured in 74 different body areas in patients with systemic sclerosis and compared with the skin score obtained from the same areas. Results: The cutometer produced quantitative and reproducible data. A large-diameter (8 ram) measuring probe was superior to a small probe. The interobserver intraclass correlation coefficient (ICC) was 0.92; the intraobserver ICC was 0.94. A linear correlation was found with the clinical skin score; the Spearman rank correlation test was 0.69. Conclusion: The correlation with the skin score was reasonable, despite the observation that regional differences in skin elasticity were detected by the cutometer but not by the human observer, who automatically compensates for these factors and integrates them into the skin score. The high interobserver and intraobserver ICC makes the cutometer more suitable for quantifying changes in skin thickness than the subjective skin score. (J Am Acad Dermatol 1996;35:381-7.) In patients with systemic sclerosis, the sclerotic skin changes correlate with the overall disease activity and prognosis. 1, 2 The best accepted and most widely used evaluation method for skin thick- ness is the "skin score," which is based on subjec- tive examination of the skin by a trained observer. 1-11 Although the interobserver and intraobserver reli- ability of the skin score can be low] 2 it is still regarded as a suitable primary outcome variable in clinical trials because it is easy to use and clinically useful alternative methods are lacking. TM To reduce subjectivity and increase reliability, From the Departments of Dermatology a and Clinical Epidemiology and Biostatistics, b Academic Medical Centre, University of Am- sterdam. Supported by a research grant from the Dutch Health Care Council Accepted for publication March 13, 1996. Reprint requests: D. N. H. Enomoto, MD, Deparmaent of Dermatology, Academic Medical Centre, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands. Copyright © 1996 by the American Academy of Dermatology, Inc. 0190-9622/96 $5.00 + 0 16/1/73390 many investigators have tried to develop devices that can measure skin sclerosis objectively and quantita- tively. Thickening of the skin in patients with scle- roderma is caused by an increase in collagen forma- tion in the dermis and possibly or temporarily by an increased amount of edema in the skin. The amount of collagen can be measured in standard skin biopsy specimens by weighing, histomelric methods, or biochemical assays, s, 15, 16 The thickness of the der- mis can be measured with high-frequency ultra- s o u n d 6, 17-21 and possibly by nuclear magnetic reso- nance imaging. 22 As a result of the accumulation of collagen and fluid, the skin develops its thickened appearance. It becomes impossible to pinch skin into a normal skinfold. This phenomenon, known as "hidebind- ing" or "tethering," is the most impressive change in sclerotic skin and is the basis of the skin score.1 To quantify this fixation of the skin, several me- chanical instruments have been developed that can exert a controlled physical force to the skin, such as impression by a durometer, 4' 5 linear extension with 381