Incidence of diffuse parenchymal lung disease in patients meeting the Berlin definition of acute respiratory distress syndrome on mechanical ventilation.

Background: The simplicity of the diagnostic definition of acute respiratory distress syndrome (ARDS) has led to its diagnosis in patients with new-onset or exacerbation of diffuse parenchymal lung diseases (DPLDs). This study investigated the incidence of DPLDs in patients with acute hypoxic respiratory failure who met the Berlin definition. Methods: This Japan-based multicentre retrospective cohort study included patients on mechanical ventilation who met the Berlin definition. For all participants, diagnosis was made by pulmonology specialists in DPLD and thoracic radiology (blinded to clinical diagnoses) by reviewing an extensive database designed for DPLD diagnosis across 10 participating hospitals. Results: Of 13 612 patients admitted to the intensive care unit during the study period, 272 met the Berlin definition of ARDS and were included for analysis. All underwent at least one chest computed tomography scan; none underwent lung biopsy. Briefly, 182 were designated classic ARDS (67%), 69 non-IPF (idiopathic pulmonary fibrosis) DPLDs (25%) and 21 IPF (8%) by DPLD specialists. Of the 90 patients diagnosed with DPLD (IPF or non-IPF) by specialists, 35% were diagnosed with classic ARDS by intensivists at the end of the clinical course. Diagnostic classifications of classic ARDS and IPF by DPLD specialists were associated with time-to-death (adjusted hazard ratio (HR) 1.58 (95% CI 1.03-2.45), p=0.038, and adjusted HR 1.73 (95% CI 1.01-2.97), p=0.045, respectively) and in-hospital mortality (adjusted HR 1.54 (95% CI 1.06-2.23), p=0.022 for classic ARDS) Conclusion: Approximately one-third of patients within the Berlin definition were retrospectively diagnosed with new-onset or acutely exacerbated DPLD by specialists.