RT Journal Article SR Electronic T1 Clinical comparison between epidemic waves in COVID-19 hospitalized patients JF European Respiratory Journal JO Eur Respir J FD European Respiratory Society SP PA3324 DO 10.1183/13993003.congress-2021.PA3324 VO 58 IS suppl 65 A1 Ramon Cabo Gambin A1 Maria Zuil Moreno A1 Carlos Manzano Senra A1 Anna Moncusi A1 Clara Gort A1 David Benitez A1 Laia Utrillo A1 Gerard Torres A1 Ferran Barbe A1 Jessica Gonzalez YR 2021 UL http://erj.ersjournals.com/content/58/suppl_65/PA3324.abstract AB Introduction: COVID-19 is responsible for several epidemic waves worldwide with different clinical and prognostic evolution.Objective: To describe the evolution, treatment and prognosis of patients admitted for COVID-19 according to 2020’s different epidemic waves.Methods: 188 consecutive patients were selected during the first wave (March-May) and 233 during the second one (July-December). Clinical, epidemiological, prognostic and therapeutic variables were collected.Results: Patients in the first wave were older (71±14 vs 67±15 years, p=0.01), suffered more hypertension (64% vs 54%, p=0.04), chronic kidney disease (20% vs 12%, p=0.036) and had lower PaO2/FiO2 at admission (261±101 vs 289±79, p<0.001). Received drugs between waves were different: Azithromycin (45% vs 10%), Hydroxychloroquine (89% vs 0.4%), Tocilizumab (17% vs 52%, Remdesivir (0% vs 26%) and Dexamethasone (0% vs 75% (p<0.001 for all)). ICU admissions decreased (32% vs 13%, p<0.001), as well as invasive or non-invasive mechanical ventilation requirement (23% vs 4%, p<0.001; 27% vs 18%, p=0.03; respectively), with no difference in high-flow oxygen therapy (34% vs 37%, p=0.6). Hospital length was shorter during the second wave (21±20 vs 12±12 days, p<0.001), with no difference in hospital mortality (16% vs 13%, p=0.4), after 30 days of discharge (19% vs 16%, p=0.4) or in the first 30 days readmissions (10% vs 8%, p=0.5).Conclusions: During the second wave the therapeutic strategy changed which traduced into a lower proportion of ICU admissions, invasive mechanical ventilation requirement and shorter hospital stay. No differences in mortality or hospital readmissions were observed.Supported in part by CIBERESUCICOVID (COV20/0011)FootnotesCite this article as: European Respiratory Journal 2021; 58: Suppl. 65, PA3324.This abstract was presented at the 2021 ERS International Congress, in session “Prediction of exacerbations in patients with COPD”.This is an ERS International Congress abstract. No full-text version is available. Further material to accompany this abstract may be available at www.ers-education.org (ERS member access only).