Background: Early during the course of the ongoing COVID-19 pandemic, reports suggested alarmingly high incidences for thromboembolic events in critically ill patients with COVID-19 . However, the clinical relevance of these events was not reported in several studies . Additionally, more recent research showed contradictory results and suggested substantially lower rates of venous thromboembolism . Thus, the aim of the present study was to summarize evidence on the incidence of clinically relevant venous thromboembolism (VTE) -defined as VTE excluding isolated subsegmental pulmonary embolism (PE) and distal deep vein thrombosis (DVT) -in adult critically ill patients with COVID-19 .
Methods: We performed a systematic review of studies reporting the incidence of clinically relevant PE and/or DVT in critically ill patients with COVID-19 . Scientific reports published in the English language between January and October 2020 were included . We conducted a random-effects model meta-analysis to calculate incidence estimates of clinically relevant VTE and bleeding events . We also performed exploratory meta-regression and subgroup analyses of different diagnostic approaches and additional factors that possibly influenced the incidence of these outcomes .
Results: Fifty-four articles (5,400 patients) fulfilled the predefined inclusion criteria, of which 41 had a high risk of bias . The majority of included patients were male ,> 60 years, and overweight . Twenty-one studies reported the use of prophylactic doses of heparin . Pooled incidences for clinically relevant PE were estimated at 8% (95% CI , 4-11 %), for proximal DVT at 14% (95% CI , 9-20 %), and-after exclusion of studies with a high risk of bias-for the composite outcome of VTE at 18% (95% CI , 13-24 %). Clinically relevant bleeding occurred at a rate of 6% (95% CI , 2-9 %).
Conclusions: We summarized currently available data on the rate of clinically relevant VTE in critically ill patients with COVID-19. Pooled incidence estimates were lower than those reported by previous review articles . In the absence of evidence-based anticoagulation guidelines for critically ill patients with COVID-19, the results of our study provide clinically important information for an individual risk-benefit assessment in this context . Registration: The study protocol was prospectively registered in PROSPERO on June 22 , 2020 (CRD42020193353; https: //www.crd.york.ac.uk/prospero).
Index: COVID-19, critically ill patients, deep vein thrombosis, incidence, pulmonary embolism, venous thromboembolism