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Quantification of hardness, elasticity and viscosity of the skin of
patients with systemic sclerosis using a novel sensing device
(Vesmeter):
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a proposal for a new outcome measurement procedure
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Oxford Journals
Rheumatology Volume 47, Number 7
2008年7月
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Y. Kuwahara1, Y. Shima1, D. Shirayama2, M. Kawai1, K. Hagihara1,
T. Hirano1, J. Arimitsu1, A. Ogata1, T. Tanaka1 and I. Kawase1
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※1:Department of Respiratory Medicine, Allergy and Rheumatic Diseases, Osaka University Graduate School of Medicine, Osaka
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※2:WaveCyber Co. Ltd., Saitama, Japan.
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Abstract |
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Objectives. No objective method to measure skin involvement in
SSc has been established. We developed a novel method using a
computer-linked device to simultaneously quantify physical properties
of the skin such as hardness, elasticity and viscosity.
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Methods.Skin hardness was calculated by measuring the depth of
an indenter pressed onto the skin. The Voigt model was used to
calculate skin elasticity, viscosity, visco?elastic ratio and relaxation
time by analysing the waveform of skin surface behaviour.
The results were compared with the modified Rodnan skin score (mRSS)
obtained at 17 sites on the bodies of 20 SSc patients and 20 healthy controls.
A functional assessment questionnaire was administered to determine how skin
hardness represents a patient's disability. We also examined intra- and
inter-observer variability to determine the reliability of this method.
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Results.The crude hardness obtained with this device correlated
well with the standard hardness specified by the American Society for
Testing and Materials (ASTM, r = 0.957). A close relationship between
hardness and total mRSS was also observed (r = 0.832).
Skin elasticity correlated positively, and relaxation time negatively with mRSS.
Functional disability correlated more closely with skin hardness (r = 0.643)
than with mRSS (r = 0.517). Intra- and inter-observer variabilities
were 7.63 and 19.76%, respectively, which were lower than those reported for mRSS.
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Conclusions.Increases in hardness and elasticity as well as shortening
of relaxation time constitute objective characteristics of skin involvement in SSc.
The system devised by us proved to be able to assess skin abnormalities of SSc
with high reliability.
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KEY WORDS: Systemic sclerosis, Scleroderma, Skin hardness, Skin elasticity,
Skin viscosity, Visco?elastic ratio, Relaxation time, Skin score,
Sensing device, Computer-assisted device
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