Factors associated with deep venous thrombosis in patients infected with coronavirus disease 2019: a meta-analysis

Coronavirus disease 2019 (COVID-19) has affected more than 6 million patients worldwide. Deep venous thrombosis (DVT) has been increasingly recognized complication in these patients and is associated with increased morbidity and mortality. However, the factors associated with development of DVT in patients with COVID-19 have not been elucidated due to the novelty of the virus. We performed a meta-analysis of published studies comparing laboratory results in COVID-19 patients with and without DVT with the aim of identifying risk factors. We searched major databases for studies evaluating DVT in COVID-positive patients and performed a meta-analysis of baseline laboratory markers associated with development of DVT. A total of six studies with 678 patients were included in the pooled analyses. Of the 678 patients, 205 of patients had a DVT. Patients diagnosed with DVT were more likely to be older [mean difference 4.59 years, 95% confidence interval (CI) 1.25-7.92], and needing admission to ICU (relative risk 1.96, 95% CI 1.09-3.51). Patients with DVT had significantly higher white cell count (mean difference 1.36 × 109/l, 95% CI 0.33-2.40) and d-dimer levels (mean difference 3229.8, 95% CI 1501.5-4958.1). Lymphocyte count was lower in patients with DVT (mean difference -0.19 × 109/l, 95% CI -0.37 to -0.02). Patients with COVID-19 who develop DVT are more likely to be older and have leukocytosis with lymphopenia. Moreover, d-dimer is statistically higher and patients that are admitted to the ICU are at great risk to develop DVT.