Anticoagulant Use as an Independent Risk Factor and Higher In-Hospital Mortality in Patients Showing Alveolar Hemorrhage in Diffuse Lung Disease

Background and objectives: Bronchoalveolar lavage (BAL) is commonly performed to evaluate diffuse lung disease and occasionally to identify alveolar hemorrhage. However, the clinical impact of alveolar hemorrhage and its risk factors in patients with diffuse lung disease have not been clarified. Materials and Methods: We retrospectively analyzed the medical records of all patients who underwent BAL to evaluate diffuse lung disease from January 2017 to December 2020. Alveolar hemorrhage was defined as progressive hemorrhagic BAL fluid or the presence of ≥20% hemosiderin-laden macrophages in the BAL fluid. Logistic regression analysis was performed to assess the association between alveolar hemorrhage and other factors. Results: Sixty subjects were enrolled in this study. Alveolar hemorrhage was observed in 19 subjects (31.7%) with idiopathic interstitial pneumonia, acute respiratory distress syndrome, interstitial pneumonia with autoimmune features, drug-induced lung injury, eosinophilic pneumonia, adenocarcinoma, and systemic lupus erythematosus. The use of anticoagulants was a significant risk factor for alveolar hemorrhage (odds ratio 7.57, p = 0.049). Patients with alveolar hemorrhage required intubated mechanical ventilation more frequently (63.2% vs. 24.4%, p = 0.005) and had higher in-hospital mortality rates (26.3% vs. 4.9%, p = 0.028) than those without alveolar hemorrhage. Conclusions: Alveolar hemorrhage was observed in various etiologies. The use of anticoagulants was a significant risk factor for alveolar hemorrhage. Patients with alveolar hemorrhage showed more severe respiratory failure and had higher in-hospital mortality than those without alveolar hemorrhage.