Does sublingual microscopy correlate with nailfold videocapillaroscopy in systemic sclerosis?

In this study, we examine sublingual videomicroscopy and nailfold videocapillaroscopy (NVC) features in systemic sclerosis (SSc) patients presenting for routine care. Consented participants met classification criteria for SSc. Sublingual videomicroscopy testing was performed in each subject, followed by a NVC assessment. Sublingual assessment provided a density measurement, red blood cell fraction (RBC fract), and perfused boundary region (PBR) score. NVC evaluator defined nailfold findings as normal; specific changes for "early," "active," and "late" scleroderma pattern; or "non-specific" changes. Microangiopathy evolution score was calculated for each participant. Statistical evaluation was performed by non-parametric tests to assess the correlation of the two tools. Thirty-nine SSc patients with limited cutaneous disease participated in this study. Most participants had late pattern NVC. There was a highly significant association between the total sublingual microvascular density and number of capillaries measured by NVC (r = 0.569, P = 0.0002), and statistically significant negative correlation between sublingual total microvascular density and microangiopathy evolution score (r = 0.532, P = 0.0006). There was significant, negative correlation between the total sublingual microvascular density and disorganization of vascular array and capillary ramification (r = 0.461, P = 0.003) and degree of giant capillaries (r = 0.387, P = 0.01). There was no correlation between RBC fract and PBR with NVC parameters. This study showed a significant correlation between sublingual videomicroscopy and NVC in terms of sublingual total microvascular density and microangiopathy evolution score. These preliminary results further support the serial use of a non-invasive and automated sublingual microvascular function testing and glycocalyx measurement in the clinical setting. KEY POINTS: • Tools that longitudinally assess microvascular function and morphologic features are important for monitoring SSc vasculopathy. • Nailfold and sublingual microscopy can identify a loss of capillary density in SSc patients.