Background Systemic sclerosis (SSc) is characterized by increased dermal thickness (DT) (1,2). The modified Rodnan skin score (mRSS) is a standard outcome measure used to evaluate the severity and extent of skin involvement (3,4). Both, high frequency ultrasounds (US) and plicometer skin test (Plicometry) have been proposed to study skin involvement in SSc patients (5-8).
Objectives The aim of this study was to identify possible correlations between mRSS, US and Plicometry during the evaluation of DT in patients with SSc.
Methods Seventy SSc patients (mean age 63±12SD years, mean SSc duration 6±5 years) and sixty-three healthy subjects (mean age 65±15SD years) were enrolled after informed consent, between September 2012 and March 2013. All patients were taking aspirin and, if necessary, cyclic intravenous prostanoids and endothelin-1 receptor antagonists. The patients were evaluated, in same session, at their normal follow-up. During the entire procedure the same equipment was used and the data were recorded by the same operators. The three aforementioned methods (mRSS, US and Plicometry) were employed to study DT in the seventeen areas of the skin usually evaluated by mRSS (face, fingers, dorsum of hands, forearms, arms, chest, abdomen, thighs, legs and feet) and the total score calculated, as previously reported (1,3,4,8). The three tests were repeated by 2 blind operators to evaluate inter- and intra-observer variability. Statistical evaluation was performed by non parametric tests.
Results A significant positive correlation was found between the three methods used to evaluate DT in the SSc patients (mRSS vs US r=0.53, p<0.0001; mRSS vs Plicometry r=0.98, p<0.0001; US vs Plicometry r=0.53, p<0.0001). US showed that SSc patients have a statistically significant higher DT at the level of the studied areas when compared with control subjects (p=0.0001). In particular, the means ± standard deviation of the sum of the US measures of the 17 body areas were 17.9±1.9 and 14.7±0.6 millimetres, for SSc patients and controls respectively. Both intra- and inter-observer variability were assessed for the three methods. The intraclass correlation coefficients for mRSS was 0.92 for the inter-observer variability and 0.95 for the intra-observer variability, for US 0.95 and 0.97 respectively, and for Plicometry 0.94 and 0.96 respectively. The necessary time to collect the data for mRSS was almost ten minutes, for Plicometry fifteen minutes and for the US was twenty minutes.
Conclusions This study demonstrates a significant relationship between mRSS, US and Plicometry in DT evaluation in SSc patients. At the level of the seventeen skin areas analyzed by US SSc patients seem to show a statistically significant higher DT than controls.
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Disclosure of Interest None declared
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