Increased monocyte count as a prognostic biomarker in patients with interstitial lung disease with autoimmune features

<bold>Introduction:</bold> Interstitial Lung Diseases(ILD) with autoimmune features comprise an heterogenous clinical entity with unpredictable course. Given its prognostic value in patients with Idiopathic Pulmonary Fibrosis, peripheral blood monocyte count may have a prognostic role in patients with interstitial lung disease with autoimmune features. <bold>Aim:</bold> To investigate the prognostic value of peripheral blood monocytes in patients with autoimmune-related ILD. <bold>Method:</bold> Treatment-naïve patients were retrospectively enrolled in the study from 29/01/2018 to 27/09/2023 and divided into subgroups (high and low) based on the median baseline monocyte count. <bold>Results:</bold> One hundred thirty-two patients(n=132) were included in the study [male:41(31%), median age 68.5 years(95%CI: 67.26 to 70.70)]. Forty-seven patients(n=47, 36%) had interstitial lung disease associated with rheumatoid arthritis, fourteen(n=14, 11%) with scleroderma, twenty-eight (n=28, 21%) with idiopathic inflammatory myopathies, eleven(n=11, 8%) with IPAF and thirty-two (n=32, 24%) with other autoimmune diseases. Patients with monocytes<560/µL had higher median FVC%pred compared to patients with monocytes ≥560/µL [87 (95%Cl: 82.70 to 94.43) vs 76 (95%Cl: 66.56 to 85.43), p= 0.0072] at the time of diagnosis and at one year of follow-up [91 (95%Cl: 82 to 93) vs. 79 (95% Cl: 68.21 to 85.39), p=0.009]. Kaplan-Meier analysis demonstrated higher all-cause mortality in patients with high vs low monocyte group [HR: 2.16 (95%Cl: 0.87 to 5.85), p=0.094]. <bold>Conclusion:</bold> Increased blood monocyte count may represent a negative prognostic biomarker for patients with autoimmune-related ILD. Further multicentered studies are sorely needed.