COVID-19 Evidence Alerts
from McMaster PLUSTM

Current best evidence for clinical care (more info)

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Primary Prevention Patell R, Chiasakul T, Bauer E, et al. Pharmacologic Thromboprophylaxis and Thrombosis in Hospitalized Patients with COVID-19: A Pooled Analysis. Thromb Haemost. 2021 Jan;121(1):76-85. doi: 10.1055/s-0040-1721664. Epub 2020 Dec 30.

BACKGROUND: Coronavirus disease 2019 (COVID-19) increases thrombosis in hospitalized patients prompting adoption of different thromboprophylaxis strategies. Safety and efficacy of escalated-dose pharmacologic thromboprophylaxis are not established.

OBJECTIVES: To determine the pooled incidence of thrombosis/bleeding in hospitalized patients with COVID-19 for standard-dose, intermediate-dose, therapeutic anticoagulation, and no pharmacologic thromboprophylaxis.

METHODS: MEDLINE, EMBASE, and Cochrane CENTRAL were searched up to August 29, 2020 for studies reporting pharmacologic thromboprophylaxis and thrombosis or bleeding. Pooled event rates were calculated using a random-effects model.

RESULTS: Thirty-five observational studies were included. The pooled incidence rates of total venous thromboembolism (N = 4,685) were: no prophylaxis 41.9% (95% confidence interval [CI]: 28.1-57.2, I2 = 76%), standard-dose prophylaxis 19.8% (95% CI: 13.2-28.6, I2 = 95%), intermediate-dose prophylaxis 11.9% (95% CI: 4.3-28.6, I2 = 91%), and therapeutic-dose anticoagulants 10.5% (95% CI: 4.2-23.8, I2 = 82%, p = 0.003). The pooled incidence rates of arterial thrombosis (N = 1,464) were: no prophylaxis 11.3% (95% CI: 5.2-23.0, I2 = 0%), standard-dose prophylaxis 2.5% (95% CI: 1.4-4.3, I2 = 45%), intermediate-dose prophylaxis 2.1% (95% CI: 0.5-7.7, I2 = 45%), and therapeutic-dose anticoagulants 1.3% (95% CI: 0.2-8.8, I2 = 0, p = 0.009). The pooled bleeding event rates (N = 6,393) were nonsignificantly higher in therapeutic-dose anticoagulants compared with standard-dose prophylaxis, (6.3 vs. 1.7%, p = 0.083).

CONCLUSION: Thrombosis rates were lower in hospitalized COVID-19 patients who received pharmacologic thromboprophylaxis. Thrombosis and bleeding rates for patients receiving intermediate-dose thromboprophylaxis or therapeutic anticoagulation were similar to those who received standard-dose pharmacologic thromboprophylaxis.

Discipline / Specialty Area Score
Hospital Doctor/Hospitalists
Internal Medicine
Intensivist/Critical Care
Hemostasis and Thrombosis
Comments from MORE raters

Hemostasis and Thrombosis rater

Confirms that VTE incidence is high when no prophylaxis is given, although assessment of magnitude is limited by the inclusion of asymptomatic events.

Intensivist/Critical Care rater

With RCTs coming, the results of observational studies are losing relevance. I do not think 'no prophylaxis' is an option.

Intensivist/Critical Care rater

The pathology in question has dire consequences. Hurriedly adopted strategies in anticoagulation / thromboprophylaxis needed the clarification provided by this article.

Internal Medicine rater

This is an important research question: Should we be using higher doses of thromboprophylaxis in COVID patients? Unfortunately, this meta-analysis of observational studies does not answer this important question. HOWEVER, there are a number of RCTs being completed that will address this and have practice-changing potential.

Internal Medicine rater

Hospitalized patients with Covid-19 have a high incidence of venous and arterial thrombosis, but there is no consensus on the optimal strategy to prevent thrombosis. This meta-analysis looked at observational studies (no controlled trials were found) and found that full therapeutic anticoagulation markedly reduced events c/w no anticoagulation, and somewhat better than standard prophylaxis with non-significantly more bleeding.