High NEMO score values in nailfold videocapillaroscopy are associated with the subsequent development of ischaemic digital ulcers in patients with systemic sclerosis

Background: Nailfold videocapillaroscopy (NVC) is a feasible method that allows the observation of the microvascular changes that mark the course of systemic sclerosis (SSc). In previous studies, we demonstrated that the NEMO score, i.e. the cumulative number of microhaemorrhages and microthromboses, is a good indicator of the steady-state level and overtime changes of disease activity (DA) in SSc. Objectives: To verify whether high NEMO scores, which mirror a very active microvascular derangement in the fingers, may be associated with the subsequent development of ischaemic digital ulcers (IDUs). Methods: The NEMO score was assessed at baseline (T0) in 98 patients with SSc, all classified according to the ACR-EULAR criteria. Of them, 90 were females, 48 had the limited and 50 had the diffuse cutaneous variant of SSc. Afterwards, the patients were closely followed up for 2 years, and the appearance of new IDUs recorded at any time of the follow-up. The T0-NEMO score values of patients who developed IDUs were compared to those of patients who did not. A receiver operating curve (ROC) was constructed, and the area under the curve (AUC) calculated by plotting the sensitivity and 1-specificity of the different NEMO score values in predicting the subsequent development of IDUs. Results: During the follow-up, 38 out of 98 patients developed one or more IDUs. The NEMO score at T0 was significantly higher in those who developed IDUs with respect to those who did not [median 14.5 (95% CI 11.0–21.5) and 4.5 (95% CI 4.0–6.0), respectively, p < 0.0001]. The ROC curve derived from different T0-NEMO score values had an AUC of 0.79 (95% CI 0.69–0.86, p < 0.0001). A NEMO score of ≥ 12 had a sensitivity of 83.3% (95% CI 71.5–91.7) and a specificity of 63.2% (95% CI 46.0–78.2), with positive (P) and negative (N) predictive (PV) values of 58.9% (95% CI 44.7–72.2) and 85.6% (71.8–94.4), respectively. A NEMO score of ≥ 16 had a sensitivity of 95.0% (95% CI 86.1–99.0) and a NPV of 93.4% (77.5–99.2). Conclusions: Being a valid tool to measure DA levels in SSc, the NEMO score also appears to be closely related to the subsequent development of IDUs in this disease.