RT Journal Article SR Electronic T1 Increased monocyte count and red cell distribution width represent negative prognostic markers in patients with Hypersensitivity Pneumonitis JF European Respiratory Journal JO Eur Respir J FD European Respiratory Society SP 1077 DO 10.1183/13993003.congress-2020.1077 VO 56 IS suppl 64 A1 Theodoros Karampitsakos A1 Evangelos Bouros A1 Ourania Papaioannou A1 Stamatios Tsipilis A1 Chrysoula Antonou A1 Maria Ntassiou A1 Serafeim Chrysikos A1 Aris Anagnostopoulos A1 Kuriaki Cholidou A1 Evangelia Koukaki A1 Matthaios Katsaras A1 Vassilios Tzilas A1 Katerina Dimakou A1 Demosthenes Bouros A1 Argyrios Tzouvelekis YR 2020 UL http://erj.ersjournals.com/content/56/suppl_64/1077.abstract AB Introduction: Hypersensitivity pneumonitis (HP) represents a chronic lung disease with limited clinically applicable biomarkers.Aim: To investigate differences in parameters of HP severity based on subgroups of monocyte count and red cell distribution width (RDW).Methods: Treatment-naïve patients with HP were prospectively enrolled in the study between 1/11/2018 and 14/02/2020. Monocyte count and RDW at baseline were recorded.Results: Fifty one patients (n=51) were enrolled [29 males, median age: 69 years (95% CI: 64.0 to 71.9), median FVC%pred: 69.0 (95% CI: 55.0 to 73.9), median DLCO%pred: 37.0 (95%CI: 29.9 to 45.0), median monocyte count: 0.610 K/μL (95% CI: 0.558 to 0.698), median RDW: 14.0 (95% CI: 13.7 to 14.7)]. Patients with monocyte count>0.610 K/μL had significantly lower FVC%pred [median: 53.0, (95% CI: 48.2 to 72.0), vs. 73.0, (95% CI: 60.5 to 86.8), p= 0.03)] and DLCO%pred [median: 32.0, (95% CI: 25.1 to 42.4) vs. 43.0, (95% CI: 31.7 to 63.3), p=0.04] compared to patients with monocyte count<0.610 K/μL, respectively. Patients with RDW>14.0 had significantly lower FVC%pred [median: 54.0, (95% CI: 46.0 to 73.0) vs. 71.0, (95% CI: 58.5 to 85.3), p=0.02] compared to patients with RDW<14.0.Conclusion: Increased monocyte count and RDW may represent negative prognosticators in patients with HP. Studies providing mechanistic insights are eagerly awaited.FootnotesCite this article as: European Respiratory Journal 2020; 56: Suppl. 64, 1077.This abstract was presented at the 2020 ERS International Congress, in session “Respiratory viruses in the "pre COVID-19" era”.This is an ERS International Congress abstract. No full-text version is available. Further material to accompany this abstract may be available at www.ers-education.org (ERS member access only).