Prevalence, Outcomes and Healthcare Costs of Postoperative ARDS Compared with Medical ARDS.

: Postoperative acute respiratory distress syndrome (ARDS) is a recognized complication with reported prevalence rates of up to 20% and highly variable mortality. However, there is limited published evidence comparing the outcomes of postoperative ARDS with those of medical ARDS. We aimed to evaluate the prevalence, hospital mortality, and healthcare costs of postoperative ARDS in Spain between 2000 and 2022 and to compare them with those of medical ARDS. : We performed a nationwide, registry-based study of all hospitalizations for postoperative ARDS in Spain between 1 January 2000 and 31 December 2022 using the Minimum Basic Data Set (MBDS) Registry. : We identified a total of 93,192 ARDS patients, of which 40,601 had postoperative ARDS. The postoperative ARDS prevalence varied between 0.05 and 0.22%, accounting for 45-50% of total ARDS cases recorded during the study period. Hospital mortality was lower in postoperative ARDS compared with medical ARDS during the first phase (2000-2015) (47.0% vs. 49.9%, < 0.001) and converged during the second phase (2017-2022) (42.7% vs. 43.2%, = 0.413). Postoperative ARDS was associated with a longer hospital stay and 1.5 times higher healthcare costs compared with medical ARDS. During the COVID-19 pandemic, mortality rates declined but costs peaked in both groups. The incidence of digestive tract infection was higher in postoperative ARDS. : The prevalence of postoperative ARDS remained stable, except during the COVID-19 pandemic, and its hospital mortality declined and equalized with that of medical ARDS. However, the costs associated with postoperative ARDS remained significantly higher.