Early reports indicated that in COVID-19 may be associated with coagulation dysfunction. Studies have reported varying rates of thromboembolism.

In this paper, the Authors searched PubMed, Cochrane and Embase for systematic reviews and meta-analyses evaluating thromboembolism rates in COVID-19 published until June 12, 2020.

The search terms were “COVID-19”, “SARS-CoV-2” or “novel coronavirus” and “venous thromboembolism”, “arterial thromboembolism”, “deep vein thrombosis” or “pulmonary embolism”.

There were varying rates of venous and arterial thromboembolism rates reported by several articles. Some studies noted TE rates in the range of 20-30% while others reported rates as high as 40-70%. However, there were no published systematic reviews and meta-analyses evaluating thromboembolism in COVID-19.

This apaper assesses and provides summary estimates of the overall thromboembolism rates of COVID-19 and further evaluates the impact of thromboembolism on COVID-19 mortality risk.

This is the first systematic review and meta-analysis to provide pooled estimates of both the venous and arterial thromboembolism rates of COVID19 and the associated mortality risk.

The evidence of 42 studies were evaluated: the overall arterial and venous and thromboembolism rates of COVID-19 were significantly high. COVID-19 patients who developed thromboembolism were at a significantly higher odds of mortality compared to those who did not.

Of 425 studies identified, 42 studies enrolling 8271 patients were included in the meta-analysis.
Overall venous TE rate was 21% (95% CI:17-26%): ICU, 31% (95% CI: 23-39%).

Overall deep vein thrombosis rate was 20% (95% CI: 13-28%): ICU, 28% (95% CI: 16-41%); postmortem, 35% (95% CI:15-57%).

Overall pulmonary embolism rate was 13% (95% CI: 11-16%): ICU, 19% (95% CI:14-25%); postmortem, 22% (95% CI:16-28%).

Overall arterial TE rate was 2% (95% CI: 1-4%): ICU, 5% (95%CI: 3-7%).

Pooled mortality rate among patients with TE was 23% (95%CI:14-32%) and 13% (95% CI:6-22%) among patients without TE. The pooled odds of mortality were 74% higher among patients who developed TE compared to those who did not (OR, 1.74; 95%CI, 1.01-2.98; P = 0.04).

The available evidence indicates that COVID-19 poses a significant risk of thromboembolism and that strategies that succeed in preventing the development of thromboembolism could reduce COVID-19 mortality. This underscores the need for clinicians to implement thromboprophylaxis protocols in order to reduce the thromboembolism risk among COVID-19 patients and to potentially reduce the mortality risk of thromboembolism.

Further research is however needed to determine the optimal dosing of anticoagulation and its mortality benefitamong COVID-19 patients.