Nailfold videocapillaroscopy-defined capillaroscopic abnormality burden in systemic lupus erythematosus: a controlled cross-sectional study.

INTRODUCTION/OBJECTIVES: Nailfold videocapillaroscopy (NVC) abnormalities are recognized in systemic lupus erythematosus (SLE), but their meaning remains uncertain. We examined whether standardized NVC quantifies structural capillaroscopic abnormality burden in SLE. METHODS: In this single-centre cross-sectional study, 65 SLE patients and 46 non-autoimmune controls underwent standardized NVC. Six parameters were semi-quantitatively scored and combined into microangiopathy, morphological, and total scores. Between-group associations were assessed using adjusted negative binomial regression. Within-SLE correlation, treatment-adjusted, and exploratory cluster analyses were performed. RESULTS: Total score was higher in SLE than controls (15 [10-21] vs. 2 [0-4], p < 0.001). After adjustment for age, sex, BMI, smoking, diabetes, and hypertension, SLE was associated with total (IRR 7.64, 95% CI 4.93-11.84), microangiopathy (IRR 9.48, 95% CI 5.94-15.14), and morphological scores (IRR 5.99, 95% CI 3.84-9.35; all p < 0.001). Density loss showed the largest component-level estimate (IRR 129.68, 95% CI 30.67-548.26) and was interpreted cautiously because of sparse controls. Microhaemorrhages were not associated with SLE (IRR 1.35, p = 0.452). Within SLE, only giant capillaries showed nominal correlations with disease duration (ρ = 0.298, p = 0.016) and neutrophils (ρ = 0.271, p = 0.029); serological signals were FDR-negative. Organ-level models were largely negative; musculoskeletal and discoid signals attenuated after treatment adjustment. Exploratory clustering identified low/high-burden groups (n = 52/13; silhouette 0.479), with limited high-burden stability. CONCLUSIONS: Standardized NVC identified greater structural capillaroscopic abnormality burden in SLE, but not a surrogate for activity, serology, organ involvement, or treatment response. Prognostic or clinical utility requires prospective multicentre validation incorporating cumulative treatment exposure.