NEMO score in nailfold videocapillaroscopy is a good tool to assess both steady state levels and overtime changes of disease activity in patients with systemic sclerosis: a comparison with the proposed composite indices for this disease status entity

BACKGROUND: In previous studies, we demonstrated that the NEMO score, i.e. the cumulative number of microhaemorrhages (MHEs) and microthromboses (MTs), observed in nailfold videocapillaroscopy was a good indicator of the steady state level of disease activity (DA) in patients with systemic sclerosis (SSc) when the European Scleroderma Study Group (EScSG) index was considered the gold standard. AIM OF THE STUDY: To verify whether the NEMO score could be (i) a valid tool to assess DA, even when the modified European Scleroderma Trials and Research (EUSTAR) index was considered to be the comparator, and (ii) a sensitive method to capture the DA overtime changes. PATIENTS AND METHODS: The NEMO score and the EScSG and EUSTAR indices were contemporarily assessed at baseline (T0) and after a follow-up of 4–56 months (T1) in 98 patients with SSc. The differences (Δ) between the T1 and T0 values of the NEMO score and the EScSG and EUSTAR indices were calculated and compared to each other. RESULTS: NEMO score values were very closely correlated with the corresponding values of the EScSG and EUSTAR indices both at T0 and T1 observations (p < 0.0001 in all cases with the exception of the correlation with EScSG values at T1 (p < 0.03)). The values of the two composite DA indices were also strictly related to each other in both T0 and T1 observations (p < 0.0001). Receiver operating characteristic (ROC) curve analysis showed the NEMO score had a good sensitivity and specificity in classifying patients with a predefined level of DA (scores ≥ 3.0 and ≥ 2.5 for the EScSG and EUSTAR indices, respectively, p < 0.0001 in both cases). Δ values of the NEMO score were significantly correlated with the corresponding values of both the EScSG and EUSTAR indices. Weighted Cohen’s k level of agreement between Δ values of the NEMO score and those of the EScSG and EUSTAR indices was moderate (0.55 and 0.59, respectively). CONCLUSIONS: NEMO score proves to be a feasible, non-invasive, and valid tool to assess steady state levels and changes over time of DA in patients with SSc. Thus, it can represent an alternative or complementary method to measure this disease status entity in this disorder.