CAPILLAROSCOPIC SKIN ULCER RISK INDEX (CSURI) IN SYSTEMIC SCLEROSIS: RESULTS FROM AN ITALIAN MULTICENTER VALIDATION STUDY

Background: Digital ulcers (DU) represent one of the most frequent complications of microangiopathy in systemic sclerosis (SSc). Recently, we developed a capillaroscopic skin ulcers risk index (CSURI), to detect patients at risk to develop DU. CSURI takes into account maximum capillary diameter (D) in a videocapillaroscopic image, number of giant capillaries (M), and number of capillaries (N), following the formula: D × M/N2. CSURI showed a sensitivity and specificity of 94.3% and 85.9% respectively, at the cut-off value of 2.94, with an area under a ROC curve of 0.926.Objectives: Aim of our multicenter study is to validate the predictive value (PV) of CSURI in a larger series of SSc patients (pts).Methods: Two hundred and fifty-nine unselected SSc pts from 10 Italian rheumatologic centers were consecutively enrolled for the study during a six-month period. Capillaroscopic parameters were defined and collected according to our previous study. With regards to their clinical history of DU, 106 pts have never experienced DU, 63 have had DU more than one year before, 42 have experienced ulcers in the last year, while 48 pts presented DU at the baseline. All pts underwent videocapillaroscopy at baseline; after three-month follow-up, they were evaluated for the possible development or persistence of DU.Results: During the follow-up period, DU were observed in 71/259 pts; in particular, 48 subjects experienced new DU, whereas 23 pts showed the persistence of ulcers already present at the baseline. The ROC curve analysis showed an area under the curve of 0.861 (95%CI 0.812-0.901) for new ulcer appearance or non-healing ulcers, with specificity and sensitivity of 78.1% (95%CI 71.6–83.8) and 92.96% (95%CI 84.3–97.6) respectively, at the cut-off value of 2.96 (the positive and negative likelihood ratios were 4.26 and 0.09 respectively).The overall PV of CSURI was 61.7%. On the other hand, the negative PV was confirmed to be very high (96.7%), considering that only 5/152 pts with CSURI ≤2.96 had DU. Among pts with recent history of DU, 58.9% of them presented DU within 3 months by NVC. In this group, CSURI had a positive PV of 78.5% and a negative PV of 92%. With regard to the healing of DU, 23 pts continued to have DU 3 months and CSURI showed a negative PV of healing of 80.8%. On the contrary, 81.8% of the pts with CSURI <2.96 showed a regression of DU. Of interest, 15/18 pts without a recent history of DU, and with DU during the follow-up, were correctly identified by CSURI.Conclusions: This multicenter study confirms the high PV of CSURI, which is able to identify SSc pts at high risk to develop new DU. The introduction of this reliable tool in the clinical practice may permit the early detection of these pts, along with a better preventive treatment strategy and reduction of morbidity and social costs.