Capillaroscopic Skin Ulcers Risk Index (CSURI) calculated with different videocapillaroscopy devices: how its predictive values change

Digital ulcers (DU) occur in about 50% of systemic sclerosis (SSc) patients. Scleroderma DU are responsible for chronic pain and disability with the need of systemic and local treatments. Recently, capillaroscopic skin ulcer risk index (CSURI) has been validated as useful tool in predicting the appearance of new scleroderma ulcers and/or persistence of non-healing lesions, within 3 months from capillaroscopy evaluation.Since the image length of 1.57 mm might represent a critical factor for CSURI calculation, the present study aimed to evaluate the reliability of CSURI using three different videocapillaroscopy devices with distinct image widths.One hundred and seventy-six unselected SSc patients were consecutively enrolled for the study during a six-month period, using three different capillaroscopy devices (image widths of 1.33, 1.57, and 1.70 mm).After a three month-follow-up new DU or persisting non-healing ulcers were observed in 46/176 patients (26.1%). The receiver operating characteristic curve analysis for CSURI showed an area under curve respectively of 0.705 for the image width of 1.33 mm, 0.786 for the image of 1.70 mm, and 0.888 for the image width of 1.57 mm.The good sensitivity, specificity and positive predictive value of CSURI was confirmed in the whole patients' series, as well as in the three subgroups on different image widths obtained with various available devices. In addition, the negative predictive value of the capillaroscopic index remained very high regardless of the picture length adopted.