Nailfold videocapillaroscopy findings correlate with lung outcomes in idiopathic inflammatory myopathies–related interstitial lung disease

Abstract

Background: Idiopathic inflammatory myopathies (IIM) are a diverse group of muscle diseases often complicated by interstitial lung disease (ILD), which significantly impacts morbidity and mortality. Krebs von den Lungen-6 (sKL-6) has been proposed as a biomarker for ILD severity. Nailfold videocapillaroscopy (NVC) detects microvascular changes, but its diagnostic and prognostic value in IIM remains unclear. Objective: This study aimed to assess the relationship between NVC abnormalities, sKL-6 levels and pulmonary outcomes in IIM patients. Methods: A retrospective analysis was conducted in IIM patients from a reference centre, comparing those with and without ILD. Data included epidemiological, clinical and immunological features, pulmonary function tests, sKL-6 levels and NVC findings. Statistical analyses included Spearman’s rank correlation coefficient to assess the relationships between sKL-6 levels, pulmonary function tests and NVC parameters. Multiple logistic regression modelling to identify to identify predictors of IIM-ILD. Results: Among 95 patients (34% male, median age 55.3±24 years, disease duration 6.8±7 years), ILD was associated with avascular zones (P¼ 0.004), capillary loss (P¼ 0.04) and microhaemorrhages (P¼ 0.04). Negative correlations were observed between capillary loss and enlarged capillaries with forced vital capacity (%FVC) (rs¼ –0.46, P¼ 0.001; rs¼ –0.57, P< 0.0001) and diffusing capacity of the lungs for carbon monoxide (%DLCO) (rs¼ –0.32, P¼ 0.04; rs¼ –0.23, P¼ 0.03). sKL-6 levels correlated positively with ILD (rs¼ 0.77, P¼ 0.0004), microhaemorrhages (rs¼ 0.21, P¼ 0.04) and avascular areas (rs¼ 0.64, P¼ 0.03), and negatively with %FVC (rs¼ –0.47, P¼ 0.001) and %DLCO (rs¼ –0.59, P¼ 0.005). Predictors of ILD included male sex, respiratory symptoms, %FVC, %DLCO, sKL-6, anti-Jo1 positivity and NVC abnormalities. Conclusions: NVC findings, sKL-6 levels, and autoantibodies are valuable in identifying and monitoring ILD in IIM, highlighting their role in early diagnosis and management.