Objectives: To assess nailfold video capillaroscopic (NVC) abnormalities and their association with clinical features, myositis-specific autoantibodies (MSA), and myositis-associated antibodies (MAA) in a large multi-ethnic cohort of patients with idiopathic inflammatory myopathies (IIM).
Methods: We recruited 155 IIM patients from three centres in Mexico, Spain, and the USA. We evaluated the clinical and laboratory features of the patients and performed semiquantitative and quantitative analyses of the NVC. Each NVC study was defined as having a normal, non-specific, early systemic sclerosis (SSc), active SSc, or late SSc pattern. Twenty-three patients had at least one follow-up NVC when disease control was achieved. Quantitative variables were expressed as medians and interquartile range (IQR) and were compared with the Kruskal-Wallis, the Mann-Whitney U-test, and the Wilcoxon test for paired medians. Associations between qualitative variables were assessed with the χ2 test.
Results: Most patients were women (68.3%), Hispanic (73.5%), and had dermatomyositis (DM) (61.2%). Fourteen patients (9%) had a normal NVC. A non-specific abnormality pattern was the most frequent (53.9%), and was associated with joint involvement, interstitial lung disease, Jo1 autoantibodies, anti-synthetase syndrome, and immune-mediated necrotising myopathy. The SSc pattern was observed mostly in DM and overlap myositis and was associated with cutaneous features and anti-TIF-1g autoantibodies. After treatment, there was a decrease in the capillaroscopic score, the capillary diameter, and the number of avascular areas, and an increase in capillary density and bushy capillary number.
Conclusions: NVC abnormalities are related to the diagnosis, clinical features, disease activity, and autoantibodies of patients with IIM.