No difference in occurrence of VTE between COVID-19 cohorts
A new systematic review and meta-analysis indicate that there were no significant differences in the occurrence of venous thromboembolism (VTE) in patients with COVID-19 compared to those without.
“Numerous studies have confirmed an association between COVID-19 and VTE,” the authors wrote in Vascular pharmacology. It is not known whether the risk of VTE differed significantly between COVID-19 cohorts and non-COVID-19 cohorts with similar disease severity. “
The team performed a systematic literature search of MEDLINE, Embase, and Google Scholar between January 2020 and March 2021, specifically looking for studies that reported VTE in COVID-19. The search identified 4,080 citations, of which 167 were assessed for analysis. They then estimated the relative risk (RR) for the effect, measured with 95% confidence intervals.
According to the results of the study, the cumulative estimate of RR for VTE in COVID-19 patients was 1.18 (95% CI, 0.79 to 1.77; P = 0.42) compared to to those without COVID-19. There were also no differences observed in pulmonary embolism only (RR = 1.25; 95% CI, 0.77 to 2.03) and deep vein thrombosis only (RR = 0.92; 95% CI, 0.52 to 1.65). There was an increased risk of VTE in ICU hospitalized COVID-19 patients compared to non-ICU patients (RR = 3.10; 95% CI 1.54 to 6.23). In prospective studies, the risk of VTE in COVID-19 patients was also high (RR = 2.74; 95% CI 1.18 to 6.40). There was no difference in the rate of respiratory assistance.
“The present meta-analysis suggests that although VTE is common among patients hospitalized for COVID-19, the occurrence of VTE appears comparable between COVID-19 patients and those with non-COVID-19 infections,” reported wrote the authors. “However, patients with COVID-19 hospitalized in intensive care may be at the highest risk of developing VTE, being significantly higher than non-COVID-19 patients hospitalized in intensive care.”
Excessive dependence on chest scans?
In their Discussion section, the authors suggested that over-reliance on chest CT scans may have led to overdiagnosis of VTE.
“Preliminary reports described pulmonary vascular abnormalities on chest computed tomography, where vascular thickening was significantly associated with COVID-19 compared to non-COVID-19 pneumonia,” the authors wrote. “It is therefore possible that chest CT performed more systematically in COVID-19 patients led to an overdiagnosis of VTE or a distal PE whose clinical relevance remains uncertain. In addition to confirmation bias, selective reporting is also plausible in the context of the rapidly evolving COVID-19 publications over the past year. “
They added that an underreporting of VTE among people with COVID-19 hospitalized in a setting other than intensive care cannot be ruled out.
Study limitations included the bias inherent in the limited range of study designs selected for use (all included analyzes were either observational studies or case series). The studies were made up of different cohorts that were heterogeneous, and only seven studies comparing CTE in COVID-19 and non-COVID-19 patients were included. There were also limits to the length of follow-up periods in the different studies, most of which were short.
“These results should be considered exploratory and further studies are needed to confirm our results and assess the most appropriate thromboprophylaxis dosage in patients with COVID-19,” they concluded.