Outpatient and inpatient anticoagulation therapy and the risk for hospital admission and death among COVID-19 patients

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Background: Coronavirus disease 2019 (COVID-19) is associated with a hypercoagulable state. Limited data exist informing the relationship between anticoagulation therapy and risk for COVID-19 related hospitalization and mortality.

Methods: We evaluated all patients over the age of 18 diagnosed with COVID-19 in a prospective cohort study from March 4th to August 27th, 2020 among 12 hospitals and 60 clinics of M Health Fairview system (USA). We investigated the relationship between (1) 90-day anticoagulation therapy among outpatients before COVID-19 diagnosis and the risk for hospitalization and mortality and (2) Inpatient anticoagulation therapy and mortality risk.

Findings: Of 6195 patients, 598 were immediately hospitalized and 5597 were treated as outpatients. The overall case-fatality rate was 2•8% ( n = 175 deaths). Among the patients who were hospitalized, the inpatient mortality was 13%. Among the 5597 COVID-19 patients initially treated as outpatients, 160 (2.9%) were on anticoagulation and 331 were eventually hospitalized (5.9%). In a multivariable analysis, outpatient anticoagulation use was associated with a 43% reduction in risk for hospital admission, HR (95% CI = 0.57, 0.38-0.86), p = 0.007, but was not associated with mortality, HR (95% CI=0.88, 0.50 - 1.52), p = 0.64. Inpatients who were not on anticoagulation (before or after hospitalization) had an increased risk for mortality, HR (95% CI = 2.26, 1.17-4.37), p = 0.015.

Interpretation: Outpatients with COVID-19 who were on outpatient anticoagulation at the time of diagnosis experienced a 43% reduced risk of hospitalization. Failure to initiate anticoagulation upon hospitalization or maintaining outpatient anticoagulation in hospitalized COVID-19 patients was associated with increased mortality risk.

Funding: No funding was obtained for this study.

Original languageEnglish (US)
Article number101139
Pages (from-to)101139
StatePublished - Nov 2021

Bibliographical note

Funding Information:
Dr. Tignanelli has a relationship (contract/grant) with the Gates Foundation and Minnesota Partnerships to conduct randomized controlled trial(s) of Losartan in COVID-19, outside the submitted work. Dr. Haslbauer and Dr. Tzankov received funding support from the Botnar Research Centre for Child Health Foundation Research Grant on COVID-19 for all their COVID-19 related research, outside the submitted research. Dr. Lutsey received NIH grants outside the submitted work. Dr. Shah received a MHealth Fairview Learning health system K12 grant, travel award for HTRS colloquium and ASH Medical educator institute award, and has a ASH system-based hematology committee leadership role. All theother authors have nothing to disclose

Funding Information:
We acknowledge the role of M Health Fairview information technology for all their help in building and setting up the environment for this database especially Dr.Genevieve Melton-Meaux, the professor of surgery and health informatics and chief analytics and care innovation office at M Health Fairview. We also acknowledge the role of Jordyn Klein, academic assistant at the general internal medicine division of the department of medicine at the University of Minnesota, for helping the authors to adhere to the EClinicalMedicine journal editing format.

Publisher Copyright:
© 2021 The Authors


  • Anticoagulation
  • COVID-19
  • D-dimer
  • Hospitalization
  • Inpatient
  • Mortality
  • Outpatient

PubMed: MeSH publication types

  • Journal Article


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