Antinuclear antibodies in interstitial lung diseases: Prevalence and predictive factors

Introduction: Antinuclear antibodies (ANA) are autoantibodies directed against different constituents of the cell. Chronic interstitial lung diseases (ILD) are a heterogeneous group of disorders with multiple etiologies. The objective of the study was to estimate the prevalence of ANA during ILD and to determine predictive factors of their presence. Methods: It was a retrospective study including patients with confirmed ILD hospitalized in respiratory department D, between 2011 and 2016 and in whom ANA were detected at the immunology laboratory of Abderrahmane Mamie Hospital. Results: Seventy-three patients were included. The average age was 62 (29 - 90 years). A female predominance was noted (sex ratio H/F=0.4). The main etiologies found were idiopathic interstitial pneumonia (59%), connective tissue disease (23%) and sarcoidosis (5.4%). The main connective tissue diseases found were rheumatoid arthritis (n=6), antisynthetase syndrome (n=2), Sjogren9s syndrome (n=3) and systemic lupus erythematosus (n=3). The prevalence of ANA was 31.5%. The ANA title ranges from 1/80 to 1/1280. The ANA’s patterns were homogeneous (n=8), speckled (n=8), nucleolus (n=4) and cytoplasmic (n=3). The typing of ANA identified anti-SSA Ro52 in 7 patients, anti RNP in 2 patients, anti Jo1 in one patient, anti-Ribosome-P in one patient and anti Scl 70 in one patient. Associated factors with ANA were skin manifestations (25% vs 6%, p=0.046) and sedimentation rate ≥ 70 s. Conclusion: During ILD, ANA were detected in the third of patients. Skin manifestations and increased sedimentation rate seem to be predictive factors of their positivity.