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

Objectives: 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. 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 center, 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 (p= 0.004), capillary loss (p= 0.04), and microhemorrhages (p= 0.04). Negative correlations were observed between capillary loss and enlarged capillaries with %FVC (rs=-0.46, p= 0.001; rs=-0.57, p< 0.0001) and %DLCO (rs=-0.32, p= 0.04; rs=-0.23, p= 0.03). sKL-6 levels correlated positively with ILD (rs = 0.77, p= 0.0004), microhemorrhages (rs = 0.21, p= 0.04), and avascular areas (rs = 0.64, p= 0.03) and negatively with %FVC (rs=-0.47, p= 0.001) and %DLCO (rs=-0.59, p= 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.