Distribution of nailfold videocapillaroscopy parameters in systemic lupus erythematosus and their association with disease activity: an international blinded case–control analysis on behalf of the EULAR study group on microcirculation in rheumatic diseases

Objectives: To evaluate whether patients with systemic lupus erythematosus (SLE) have different nailfold videocapillaroscopy (NVC) findings compared with healthy controls (HCs) and whether there is an association between NVC abnormalities and disease activity, clinical and/or laboratory features in SLE. Methods: This is an observational, multicentre, international, matched case-control study. 381 subjects (203 patients with SLE and 178 HCs) were enrolled from 16 centres in 10 countries. Clinical and laboratory data were collected using ad hoc forms. 5861 NVC images were acquired, coded and uploaded for central blinded analysis. Results: A normal NVC pattern was observed in most patients with SLE (86.6%) and, a significantly higher frequency of NVC abnormalities such as enlarged and giant capillaries, microhaemorrhages and irregular nail bed architecture (p<0.001) were found in the remaining patients. Multiple correspondence analysis outlined two NVC patterns, one of which, the more severe (cluster 2), present in 12% of patients, was characterised by a higher prevalence of lower capillary density, abnormally shaped and enlarged capillaries and irregular nail bed architecture. NVC cluster 2 had significantly higher disease activity compared with cluster 1 for both Systemic Lupus Erythematosus Disease Activity Index cut-off points ≥3 and ≥4 (p=0.016 and p=0.028, respectively). SLE with 'more severe' NVC pattern (cluster 2) have a significantly higher frequency of arthritis, renal involvement and ongoing glucocorticoid therapy, whereas serositis was significantly associated with 'less severe' NVC pattern (cluster 1). Conclusions: This study has shown that changes in NVC patterns are associated with important aspects of SLE disease activity. Future prospective studies are needed to further support the use of NVC in SLE monitoring. Trial registration number: NCT02801812.