Ultrasonography for the assessment of skin in systemic sclerosis: a systematic review

Objective: To identify and synthesize the best available evidence on the use of ultrasound to assess skin involvement in systemic sclerosis (SSc). Methods: We conducted a systemic review of the literature on PubMed Medline and Embase, using the vocabulary terms ("systemic sclerosis OR scleroderma") AND ("ultrasonography" OR "elasticity imaging techniques") AND ("skin" OR "dermis"). Two independent reviewers selected articles, collected data from studies, and carried out a manual search of the references from the studies included. This search was further enhanced by a review of bibliographic references extrapolated from these studies. The quality of the evidence was assessed by the Effective Public Health Practice Project system. Results: A total of 30 studies were identified, enrolling 1,171 SSc patients, predominantly middle-aged (mean age 55.5 years) females (88.8%). The ultrasound skin measurements that were reported included thickness in 28 studies and/or echogenicity (7 studies), and/or stiffness (6 studies), and/or vascularity (1 study). The main comparator was the global and site-specific modified Rodnan skin thickness score. Reported interrater and intrarater reproducibility appeared to be excellent, but this reproducibility was assessed by a small number of studies. Moreover, there were no published evaluations of construct or criterion validity of skin ultrasound assessment. The responsiveness to change of ultrasound elastography has not been assessed. Conclusion: Published reports have strong limitations and are highly heterogeneous, hindering the evidence to support the use of skin ultrasound assessment in clinical practice. Further studies, with modern devices and appropriate methodology, are needed to establish the real value of skin ultrasound assessment in the early diagnosis and monitoring of SSc patients.