In a recent study published in Infectious diseasesIn this study, researchers estimated the incidence of arterial or venous thrombosis in patients with coronavirus 2019 (COVID-19).
COVID-19 can cause arterial/venous thromboembolism due to inflammation, platelet activation, endothelial dysfunction and stasis. Several researchers have investigated the risk of venous thromboembolism in hospitalized patients due to COVID-19. However, these studies were relatively smaller, varying in sample size, setting, and definition of outcomes resulting in significant heterogeneity. Furthermore, they have focused only on hospitalized COVID-19 patients, and the incidence of thrombotic events in non-hospitalized COVID-19 patients remains unknown.
Certain patient-related factors such as aging, obesity, high blood pressure, and diabetes are associated with a higher risk of hospitalization and death in COVID-19. Some of these agents have previously been reported to predispose people to thrombotic events. Besides, the links between thrombotic events and characteristics of COVID-19 patients have not been elucidated.
In the current study, researchers investigated the incidence of arterial and venous thromboembolism and mortality among COVID-19 patients. A cohort network study was conducted using healthcare data from the United Kingdom (UK), Spain, Germany, Italy and the Netherlands. The primary analyzes included two groups; The first group included people diagnosed with COVID-19. The second cohort consisted of hospitalized COVID-19 patients—one year of observational time was required prior to study enrollment for individuals in either cohort to be eligible for primary analyses.
The index date was defined as the date of occurrence/testing of COVID-19 for those in the first group and the date of hospitalization for those in the second group. For sensitivity analysis, the cohorts were established based on 1) clinical diagnosis alone, 2) clinical diagnosis with less specific codes to identify COVID-19, 3) exclusive polymerase chain reaction (PCR) test, 4) COVID-19 test (both antigen and PCR tests). These cohorts were also required to have one year of observation time before being included in the study.
The primary outcomes were arterial or venous thrombotic events and death within 90 days after the index date. Venous thrombosis events were identified by codes for deep vein thrombosis or pulmonary embolism. Arterial thromboembolism was defined as a stroke or myocardial infarction.
Cox models were used to assess associations between pre-specified variables and the risk of thromboembolism and death. The cumulative incidence of study outcomes was estimated and stratified by sex and age. The impact of thrombotic events on COVID-19 outcomes was assessed using a multi-state model.
The study included more than 0.9 million individuals on or after September 1, 2020, with an index. More than 415,000 of the participants were from the United Kingdom, more than 38,000 each from the Netherlands, Germany and Spain, and 25,759 from Italy. The second group included 32,329 hospitalized patients, all from Spain. Median age varied by region, and females outnumbered males in COVID-19 cases in the overall sample. The median age was 67 years in the placebo group, with a significant proportion being male. More than 23,200 people were sick or had previously been treated.
The 90-day cumulative incidence of a venous thromboembolism event in those diagnosed with COVID-19 or a positive SARS-CoV-2 PCR test ranged from 0.21% in the Netherlands to 0.8% in Spain, albeit 4.5% for those in hospital. . Similarly, the incidence of cumulative arterial thromboembolism ranged from 0.06% in the UK and Italy to 0.79% in Spain, and increased to 3.08% among hospitalized patients. Mortality was less than 2% in the first group but increased by 14.61% among hospitalized patients.
When stratified by age, arterial/venous thrombotic events and death were more prevalent in those 65 years of age or older; However, this pattern of venous thromboembolism was not observed in hospitalized patients. Males had a higher risk of arterial thromboembolism and death, whereas males from the Netherlands, the United Kingdom, and Spain but not from Germany or Italy showed an increased risk of venous thromboembolism.
Hazard ratios (HRs) after gender adjustments revealed that outpatient venous thromboembolism was associated with hospitalization (HR: 1.36) and death (4.42). Similarly, inpatients were associated with an increased risk of mortality (1.63). Arterial thrombosis events in the outpatient setting increased the risk of death (3.16), but not hospitalization, and similarly, in hospitals, the risk of death was similarly higher (1.93).
The current study calculated the incidence of thromboembolism and death among COVID-19 patients. For patients who were not hospitalized, the cumulative incidence of venous thromboembolism was 0.2% to 0.8% and 0.1% to 0.8% for arterial thrombotic events. The hospitalized group showed the highest incidence of venous and arterial thromboembolism at 4.5% and 3.1%.
Although the 90-day mortality rate never exceeded 2% for non-hospitalized patients, it was significantly higher (14.6%) for in-hospital patients. After adjustments, men had a higher risk of stroke and death. The results demonstrated that thrombotic events were associated with severe COVID-19 outcomes and mortality, leading to the need to develop strategies to reduce their incidence.