Clinical impact of antineutrophil cytoplasmic antibody positivity on the occurrence of interstitial lung disease in patients with polymyositis/dermatomyositis

Background: This study investigated the clinical impact of antineutrophil cytoplasmic antibody (ANCA) positivity on the occurrence of interstitial lung disease (ILD) in patients with probable and definite polymyositis (PM)/dermatomyositis (DM) who met both the Bohan and Peter and the 2017 European League Against Rheumatism/American College of Rheumatology criteria. Methods: The medical records of 75 PM/DM patients were retrospectively reviewed. ANCA and anti-Jo 1 positivity at diagnosis were obtained, and pulmonary function test and chest high-resolution computed tomography results at ILD occurrence were collected. The follow-up duration based on ILD was defined as the period from the time of PM/DM diagnosis to the occurrence of ILD in PM/DM patients with ILD and to the last visit for those without ILD. Results: The median age was 50.0 years and 21.3% were male. ANCA and anti-Jo 1 were detected in 12 (16.0%) and 26 patients (34.7%), respectively. ILD occurred in 32 patients, 24 of whom had ILD at the time of PM/DM diagnosis. Anti-Jo 1 was detected more often in PM/DM patients without ANCA than those with (39.7% vs. 8.3%). ILD occurred more frequently in PM/DM patients with ANCA than those without ANCA (75.0% vs. 36.5%). However, the occurrence of ILD was not affected by anti-Jo 1 positivity. Furthermore, ANCA-positive PM/DM patients exhibited a significantly lower cumulative ILD-free survival rate than ANCA-negative PM/DM patients (P=0.009). Conclusions: ANCA positivity at the time of PM/DM diagnosis might be an important risk factor for ILD in PM/DM patients.