Abstract
OBJECTIVE: Sublingual microscopy assesses systemic sclerosis (SSc) vasculopathy. Digital thermal monitoring (DTM) may identify patients at risk for digital ulcer (DU). The purpose of this analysis was to assess sublingual microscopy and DTM in SSc patients with and without previous DU in order to determine the utility of these clinical tools. METHODS: SSc registry patients with clinical data who had both DTM and sublingual microscopy on the same day were included in this cross-sectional analysis. DTM quantifies vascular reactivity index (VRI). Sublingual microscopy measures longitudinal red blood cell fraction (RBCfract) and perfused boundary region (PBR). We evaluated the pairwise association between VRI, RBCfract, and PBR in a monotonic relationship using Spearman rank correlation in the DU subset. Correlation coefficients (r ((s)) ) and their 95% CIs were reported. RESULTS: Ninety patients were included; 29 had digital pits and/or active DU and 61 never had a DU. The only significant clinical feature associated with DU was modified Rodnan skin score (P = 0.003) with DU being higher. The VRI was lower in patients with DU (P = 0.01). The higher the RBCfract, the lower PBR (r ((s)) = -0.71, 95% CI -0.86 to -0.47, P < 0.001). VRI was not associated with RBCfract or PBR (P = 0.24 or 0.55, respectively) in the patients with DU. CONCLUSION: DTM is a useful tool for assessing SSc-DU. While sublingual microscopy measurements did not significantly correlate to VRI in patients with SSc-DU, a longitudinal study may be more helpful in capturing vasculopathy activity prior to possible irreversible damage.