Timing of venous thromboembolism diagnosis in hospitalized and non-hospitalized patients with COVID-19

Background: The reported incidence of venous thromboembolism (VTE) in COVID-19 patients varies widely depending on patient populations sampled and has been predominately studied in hospitalized patients. The goal of this study was to assess the evolving burden of COVID-19 and the timing of associated VTE events in a systemswide cohort. Methods: COVID-19 PCR positive hospitalized and non-hospitalized patients >= 18 years of age tested between 1/ 1/2020 through 12/31/2020 were retrospectively analyzed using electronic medical records from multiple states across the Mayo Clinic enterprise. Radiology reports within 90 days before and after confirmed COVID-19 diagnosis were examined for VTE outcomes using validated Natural Language Processing (NLP) algorithms. Results: A 29-fold increased rate of VTE compared to the pre-COVID-19 period was noted during the first week following the first positive COVID-19 test (RR: 29.39; 95% CI 21.77-40.03). The rate of VTE steadily decreased and returned to baseline by the 6th week. Among 366 VTE events, most occurred during (n = 243, 66.3%) or after (n = 111, 30.3%) initial hospitalization. Only 11 VTE events were identified in patients who did not require hospitalization (3.0% of total VTE events). VTE and mortality increased with advancing age with a pronounced increased each decade in older patients. Conclusion: We observed a profoundly increased risk of VTE within the first week after positive testing for COVID19 that returned to baseline levels after 6 weeks. VTE events occurred almost exclusively in patients who were hospitalized, with the majority of VTE events identified within the first days of hospitalization.

Automated summary

The study found a 29-fold increased rate of VTE within the first week after COVID-19 diagnosis, which then steadily decreased and returned to baseline by the 6th week. Most VTE events occurred during or after hospitalization, with only a small percentage (3.0%) in non-hospitalized patients.