Abstract
BACKGROUND: Coronavirus disease 2019 (COVID-19) has been associated with an increased risk of stroke. It remains unclear whether the risk of stroke associated with a diagnosis of COVID-19 differed with oral anticoagulation (OAC) use. The aim of this study was to evaluate the association between COVID-19 infection, OAC use, and stroke in patients with atrial fibrillation (AF). METHODS: A retrospective cohort study was conducted in individuals with established AF using data from Optum's deidentified Clinformatics(®) Data Mart Database. Cox proportional hazard models with time-dependent variables were employed to assess the association between possession of OAC, COVID-19 diagnosis in both inpatient and outpatient setting, and time to ischemic stroke. RESULTS: A total of 561,758 individuals aged 77 ± 10 were included in the study, with a mean follow up time of 1.3 years. OAC use was associated with a reduced stroke risk [hazard ratio (HR) 0.85, 95% confidence interval (CI) 0.82-0.88]. COVID-19 infection was associated with an increased risk of stroke (HR 2.11, 95% CI 1.87-2.38); this increased risk was particularly pronounced for patients diagnosed with an inpatient diagnosis of COVID-19 (HR 3.95, 95% CI 3.33-4.68). There was no significant interaction between OAC use and COVID-19 diagnosis (p value = 0.96). As a result, the relative increase in stroke risk associated with COVID-19 did not differ between patients on OAC (HR 2.12; 95% CI 1.71-2.62) and those not on OAC (HR 2.11; 95% CI 1.83-2.43). CONCLUSION: In a nationwide sample of patients with established AF, we found the relative increase in stroke risk associated with COVID-19 was independent of OAC use.