Capillaroscopic patterns are associated with interstitial lung disease, skin fibrosis, anti-Th/To antibodies and quality of life in systemic sclerosis: a prospective cross-sectional study

Background Capillaroscopic patterns in systemic sclerosis (SSc) are routinely assessed by nailfold videocapillaroscopy (NVC), yet their broader clinical relevance remains incompletely defined. Methods In a prospective cross-sectional study of 70 SSc patients, we evaluated associations between NVC patterns and key clinical domains: interstitial lung disease (ILD), skin fibrosis (the modified Rodnan Skin Score, mRSS), SSc-specific autoantibody profile including anti-Th/To, immunosuppressive treatments, and patient-reported outcome measures (PROMs): SSc Quality of Life scale (SScQoL), Health Assessment Questionnaire-Disability Index (HAQ-DI), and Visual Analog Scales (VAS) for pain and disease activity (PtGA). Statistical methods included Spearman correlation, Mann–Whitney U -test, receiver operating characteristic (ROC) analysis, and logistic regression. p -values were adjusted using the false discovery rate (FDR). Results Advanced NVC patterns (4–5) were significantly associated with ILD ( OR = 3.73, 95% CI : 1.42–9.81, q = 0.0058), and this association remained consistent across multiple multivariable and parsimonious logistic regression models adjusting for anti-Scl-70 status, disease duration, or skin fibrosis (mRSS), with effect estimates around fourfold increased odds of ILD. ROC analysis demonstrated diagnostic discrimination for ILD based on NVC pattern ( AUC = 0.688). Higher NVC severity was also associated with greater skin fibrosis (ρ = +0.38, q = 0.0283), with progressive increases in median mRSS from NVC pattern 2 to 5 (4.0 → 11.0). Strong associations were found with PROMs: worse SScQoL ( q = 0.0040), higher HAQ-DI ( q = 0.0027), and elevated PtGA ( q = 0.0040). A novel inverse correlation was identified between NVC patterns and anti-Th/To antibody positivity ( q = 0.022). Exposure to cyclophosphamide (CYC) or mycophenolate mofetil (MMF) was associated with more severe capillaroscopic damage (both q = 0.019) most likely reflecting greater disease severity rather than a treatment effect. Conclusion Our study demonstrates significant associations between NVC severity and selected clinical, serological, therapeutic, and patient-reported domains in SSc.