Age as a Significant Factor in the Diagnosis and Prognosis of ARDS Patients Not Meeting the Berlin Criteria

Purpose: ARDS (Acute Respiratory Distress Syndrome) poses significant challenges in critical care, particularly during the COVID-19 pandemic. The new global definition of ARDS includes some patients who are not previously considered to have ARDS. This study aims to look at the prognostic characteristics of these patients and develop a prediction model. Methods: This multicenter retrospective study included 5,214 patients from the Chinese People's Liberation Army General Hospital between December 2022 and February 2023. Patients were categorized into four groups based on the 2023 Global Definition and 2012 Berlin Definition: new definition + COVID-19, new definition − COVID-19, old definition (Berlin) + COVID-19, and old definition − COVID-19. Patient characteristics were analyzed using LASSO regression and Cox proportional hazards models to identify factors associated with 28-day mortality. A prognostic model was developed using key variables. Results: Among ARDS patients, the old definition + COVID-19 group had the highest mortality, while the new definition + COVID-19 group had similar mortality to the old definition - COVID-19 group. LASSO regression identified seven factors: heart rate, lactate dehydrogenase, platelets, total bilirubin, D-dimer, age, and antiviral therapy, with age being the most significant contributor. Compared to patients younger than 75, those aged 75-85 had 1.09 times higher risk, and those over 85 had 2.78 times higher risk. Antiviral therapy was the only protective factor, reducing mortality risk by 0.42 times. The model's AUC for predicting 28-day mortality was 0.732 in the training set and 0.726 in the validation set. Conclusions: The 2023 Global ARDS definition holds significant value in identifying COVID-19 patients receiving high-flow nasal oxygen (HFNO), enabling early intervention. Age is a critical risk factor, highlighting the need for heightened clinical attention in elderly patients. Antiviral therapy showed significant mortality benefit. The seven-variable scoring system provides a practical tool for prognosis assessment in newly defined ARDS patients.