Methods for objective assessment of skin involvement in systemic sclerosis

Skin fibrosis is the most prominent disease manifestation of systemic sclerosis (SSc). Although the treatment for other SSc manifestations has expanded over the years, there is limited progress in identifying effective treatment options for SSc skin involvement. This is in part due to limitations in the utilized outcome measures for assessment of skin fibrosis. This review focuses on different emerging assessment tools for SSc skin involvement and their potential use for clinical care and multicenter trials.

Durometer and other device-based methodologies requiring application of direct pressure to the affected skin have been studied in SSc. However, there are concerns that the required application of pressure might be a source of variability. Ultrasound-based methods have been compared with modified Rodnan Skin Score in several studies, indicating acceptable construct validity. However, few studies have examined their criterion validity by providing comparisons to skin histology. Optical coherence-based methods show promising preliminary results for simultaneous assessment of skin fibrosis and vasculopathy. Further standardization and validation (including comparison to skin histology) of these promising novel assessment tools in large, longitudinal SSc cohort studies are needed to establish them as clinically useful outcome measures with acceptable sensitivity to change.

Recent advances in imaging techniques provide a promising opportunity for development of a valid and reliable assessment tool for quantification of SSc skin fibrosis, which can pave the way for approval of effective treatment options for this high burden disease manifestation.