Abstract: Ascorbic Acid as an Adjunctive Therapy in Critically Ill Patients with COVID-19: A Multicenter Propensity Score Matched Study Khalid Al Sulaiman (  alsulaimankh@hotmail.com ) King Abdulaziz Medical City Ohoud Al Juhani King Abdulaziz University Khalid Bin Salah King Abdulaziz Medical City Hisham A. Badreldin King Abdulaziz Medical City Abdullah Al Harthi King Abdulaziz Medical City Mohammed Alenazi King Saud bin Abdulaziz University for Health Sciences Aisha Alharbi King Abdulaziz University Hospital Rahmah Algarni King Abdulaziz University Hospital Shmeylan Al Harbi King Abdulaziz Medical City Abdullah Alhammad King Saud University Ramesh Vishwakarma King Abdullah International Medical Research Center Sarah Aldekhyl King Abdulaziz Medical City Research Article Keywords: COVID-19, SARS-CoV-2, Ascorbic Acid, Vitamin C, Vitamins, Critically ill, Intensive Care Units (ICUs), 30-days ICU mortality Posted Date: April 2nd, 2021 Page 1/17 DOI: https://doi.org/10.21203/rs.3.rs-354711/v1 License:   This work is licensed under a Creative Commons Attribution 4.0 International License. Read Full License Page 2/17 Abstract Background: Ascorbic acid represents an appealing option for clinicians to utilize in the context of a global health pandemic of COVID-19 patients due to its proposed clinical efficacy, relative safety, and low cost. Objectives: The aim of this study was to evaluate the efficacy and safety of using ascorbic acid in supplemental dose as adjunctive therapy in critically ill patients with COVID-19. Methods: This was a multi-center, non-interventional, retrospective cohort study. All critically ill adult patients admitted to ICU with a confirmed COVID-19 between March 1st to December 31st, 2020 were included in the final analysis. The study was conducted at two large governmental tertiary hospitals in Saudi Arabia. The purpose was to investigate the association between clinical outcomes with ascorbic acid use as an adjunctive therapy in COVID-19 after propensity score matching using baseline severity scores, systemic use of corticosteroids and study centers. Results: A 739 patients were included in this study; 296 patients were included after propensity score matching. There was no association between the administration of ascorbic acid and in-hospital mortality nor 30day ICU mortality (OR (95%CI): 0.77 (0.476, 1.234), p-value=0.2738 and OR (95%CI): 0.73 (0.438 ,1.204), p-value=0.215 respectively). Using ascorbic acid was associated with lower incidence of thrombosis compared with the non-ascorbic acid group (6.1% vs. 13% respectively); OR (95%CI): 0.42 (0.184, 0.937), p-value=0.0342). Conclusion: Supplemental dose of ascorbic acid as an adjunctive therapy in COVID19 critically ill patients was not associated with mortality benefits; but associated with lower incidence of thrombosis. Further studies are required to confirm these findings.