Abstract: medicina Article Aspirin Is Related to Worse Clinical Outcomes of COVID-19 Isaac Kim 1,† , Siyeong Yoon 2,† , Minsup Kim 3 , Hyunil Lee 4 , Sinhyung Park 5 , Wonsang Kim 3 and Soonchul Lee 2, * 1 2 3 4 5 * †



 Citation: Kim, I.; Yoon, S.; Kim, M.; Lee, H.; Park, S.; Kim, W.; Lee, S. Aspirin Is Related to Worse Clinical Outcomes of COVID-19. Medicina 2021, 57, 931. https://doi.org/ 10.3390/medicina57090931 Academic Editor: Pierpaolo Di Micco Department of General Surgery, CHA Bundang Medical Center, CHA University School of Medicine, Seongnam 13488, Korea; isaac24@cha.ac.kr Department of Orthopedic Surgery, CHA Bundang Medical Center, CHA University School of Medicine, Seongnam 13488, Korea; tldud1105@naver.com inCerebro Drug Discovery Institute, Seoul Technopark, Seoul 01811, Korea; minsupkim@incerebro.com (M.K.); wonsangkim@incerebro.com (W.K.) Department of Orthopedic Surgery, Ilsan Paik Hospital, Inje University, Goyang 10380, Korea; hyunil.lee7@gmail.com Department of Orthopedic Surgery, Bucheon Hospital, Soonchunhyang University, Bucheon 14584, Korea; greatpsh78@gmail.com Correspondence: Lsceline78@gmail.com; Tel.: +82-31-780-5289; Fax: +82-31-881-7114 Contributed equally to co-first authors. Abstract: Background and Objectives: Aspirin is used globally to reduce pain and inflammation; however, its effect in patients with coronavirus disease (COVID-19) is not fully investigated and remains controversial. We evaluated the association between aspirin and COVID-19 outcomes using nationwide data from the Korean National Health Insurance System. Materials and Methods: This was a retrospective observational cohort study that included 22,660 eligible patients who underwent COVID-19 testing in South Korea between 1 January–31 July 2020. We identified all aspirin users prescribed aspirin within two weeks before or after the index date. The primary outcome was positivity for the COVID-19 test, and secondary outcomes included conventional oxygen therapy, intensive care unit, mechanical ventilation, or death. We applied the propensity score matching method to reduce the possible bias originating from the differences in patients’ baseline characteristics. Results: Of those eligible, 662 patients were prescribed aspirin. Among them, 136 patients were on aspirin within two weeks before diagnosis and 526 patients were on aspirin after diagnosis. The COVID-19 test positivity rate was not significantly different according to aspirin use. Aspirin use before COVID-19 was related to an increased death rate and aspirin use after COVID-19 was related to a higher risk of the conventional oxygen therapy. Conclusion: Aspirin use was associated with adverse effects in COVID-19 patients. Further studies for mechanisms are needed. Received: 20 July 2021 Accepted: 2 September 2021 Keywords: COVID-19; aspirin; outcome Published: 4 September 2021 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).