Age as a significant prognostic factor in patients meeting the global ARDS definition but not the Berlin definition

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: Global-definition-only ARDS + COVID-19, Global-definition-only ARDS−COVID-19, Berlin ARDS + COVID-19, and Berlin ARDS−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 Berlin ARDS + COVID-19 group had the highest mortality, while the observed 28-day mortality in the Global-definition-only ARDS + COVID-19 group was of a similar magnitude to that in the Berlin ARDS without COVID-19 group. LASSO selected seven candidate predictors: heart rate, lactate dehydrogenase, platelet count, total bilirubin, D-dimer, age, and antiviral therapy. In the multivariable Cox model, lactate dehydrogenase, age, and antiviral therapy were independently associated with 28-day mortality. Compared with patients aged <75 years, the HRs for 28-day mortality were 2.09 (95% CI 1.07–4.10) for those aged 75 to <85 years and 3.78 (95% CI 2.08–6.86) for those aged ≥85 years. Antiviral therapy was associated with a lower hazard of 28-day mortality (HR 0.58, 95% CI 0.40–0.84).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), the Global definition may facilitate earlier identification of ARDS patients. Age is a critical risk factor, highlighting the need for heightened clinical attention in elderly patients. Antiviral therapy was associated with a lower hazard of 28-day mortality. Seven candidate predictors were selected by LASSO and evaluated in a Cox prognostic model for 28-day mortality.