POS0887 INFLUENCE OF CONTEXTUAL FACTORS AND RELIABILITY OF ULTRASOUND SKIN MEASURES IN PERSONS WITH SYSTEMIC SCLEROSIS AND HEALTHY CONTROLS

Abstract

BackgroundSkin involvement is a cardinal feature for the diagnosis and prognosis of systemic sclerosis (SSc) and is associated with worse functional ability and quality of life.[1]Gender and age have been found to influence ultrasound dermal thickness and skin stiffness, and preliminary normal reference percentile curves for these ultrasound measures have been proposed.[2]The possibility that contextual factors, like room temperature, may influence these measurement is of crucial importance, but it has been very scarcely addressed.[3]ObjectivesTo examine the influence of contextual factors upon the evaluation of skin thickness and stiffness by ultrasound and to assess the reliability of these parameters.MethodsUltrasound dermal thickness (by B-mode, 18MHz) and skin stiffness (by shear-wave elastography, 9MHz) were assessed in persons with systemic sclerosis (SSc) and in healthy controls. The influence of contextual factors upon repeated measures was evaluated: (i) room temperature (16-17ºCvs22-24ºC); (ii) time of day (morningvsafternoon), and (iii) menstrual cycle phase (menstrualvsovulatory). Differences were analyzed using the related-samples Wilcoxon signed-rank test.Inter- and intra-rater reliability of ultrasound skin thickness and stiffness were evaluated in the 17 skin Rodnan sites of 20 persons with SSc and 20 healthy controls, under stable contextual conditions.ResultsA significant increase in dermal thickness values was observed between the morning and afternoon evaluations, at the leg 6.96% (SD3.39), p=0.007, and 7.39% (8.42), p=0.018, in SSc patients and in controls, respectively (Table 1).No significant changes were observed in association with room temperature and menstrual cycle. Intra- and inter-rater-reliability was good to excellent for ultrasound dermal thickness and stiffness, both in SSc and healthy controls.ConclusionThe timing of the ultrasound procedure within each day seems to influence the ultrasound measures at the legs and feet, and this aspect should deserve attention when designing and reporting future trials. Our study corroborates that ultrasound dermal thickness and skin stiffness are reliable domains to quantify skin involvement in SSc.