Abstract: Received: 18 January 2021 Accepted: 18 January 2021 DOI: 10.1002/ajh.26102 RESEARCH ARTICLE Intermediate-dose anticoagulation, aspirin, and in-hospital mortality in COVID-19: A propensity score-matched analysis Matthew L. Meizlish1 | George Goshua2 | Yiwen Liu3 | Rebecca Fine4 | Kejal Amin5 | Eric Chang2 | Nicholas DeFilippo5,6 | Craig Keating7 | Yuxin Liu2 | Michael Mankbadi4 | Dayna McManus5 | Stephen Y. Wang4 | Christina Price8 Robert D. Bona2 | Cassius Iyad Ochoa Chaar9 | Hyung J. Chun10 | Alexander B. Pine2 | Henry M. Rinder2,11 | Jonathan M. Siner12 Donna S. Neuberg3 | Kent A. Owusu5,13 | Alfred Ian Lee2 1 Yale School of Medicine, New Haven, Connecticut, USA 2 Section of Hematology, Department of Medicine, Yale School of Medicine, New Haven, Connecticut, USA 3 Dana-Farber Cancer Institute, Boston, Massachusetts, USA 4 Department of Medicine, Yale School of Medicine, New Haven, Connecticut, USA 5 Department of Pharmacy, Yale-New Haven Hospital, New Haven, Connecticut, USA 6 School of Pharmacy, University of Connecticut, Storrs, Connecticut, USA 7 Joint Data Analytics Team, Yale New Haven Hospital, New Haven, Connecticut, USA 8 Section of Allergy and Immunology, Department of Medicine, Yale School of Medicine, New Haven, Connecticut, USA 9 Section of Vascular Surgery, Department of Surgery, Yale School of Medicine, New Haven, Connecticut, USA | 10 Section of Cardiology, Department of Medicine, Yale School of Medicine, New Haven, Connecticut, USA 11 Department of Laboratory Medicine, Yale School of Medicine, New Haven, Connecticut, USA 12 Section of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine, Yale School of Medicine, New Haven, Connecticut, USA 13 Clinical Redesign, Yale New Haven Health, New Haven, Connecticut, USA Correspondence Alfred Ian Lee, Section of Hematology, Department of Medicine, Yale School of Medicine, New Haven, CT 06510. Email: alfred.lee@yale.edu | Abstract Thrombotic complications occur at high rates in hospitalized patients with COVID19, yet the impact of intensive antithrombotic therapy on mortality is uncertain. We examined in-hospital mortality with intermediate- compared to prophylactic-dose Kent A. Owusu, Department of Pharmacy, Yale-New Haven Hospital, New Haven, CT 06510. Email: kent.owusu@ynhh.org Donna S. Neuberg, Dana-Farber Cancer Institute, Boston, MA 02115. Email: neuberg@ds.dfci.harvard.edu anticoagulation, and separately with in-hospital aspirin compared to no antiplatelet therapy, in a large, retrospective study of 2785 hospitalized adult COVID-19 patients. In this analysis, we established two separate, nested cohorts of patients (a) who received intermediate- or prophylactic-dose anticoagulation (“anticoagulation cohort”, N = 1624), or (b) who were not on home antiplatelet therapy and received Funding information National Institutes of Health, Grant/Award Numbers: HL139116, GM136651, HL142818; Hemostasis and Thrombosis Research Society; American Society of Hematology either in-hospital aspirin or no antiplatelet therapy (“aspirin cohort”, N = 1956). To minimize bias and adjust for confounding factors, we incorporated propensity score matching and multivariable regression utilizing various markers of illness severity and other patient-specific covariates, yielding treatment groups with well-balanced Matthew L. Meizlish, George Goshua, Yiwen Liu and Rebecca Fine contributed equally as first authors. Donna S. Neuberg, Kent A. Owusu and..