Anticoagulation outcomes in hospitalized Covid‐19 patients: A systematic review and meta‐analysis of case‐control and cohort studies

Summary Background: Coagulopathy and thromboembolic events are common in Covid‐19 patients and are poor prognostic factors. Controversy exists regarding the potential of anticoagulation (AC) to reduce mortality and incidence of thromboembolic events in Covid‐19 patients. The current systematic review and meta‐analysis investigated the association between anticoagulants and mortality in adult hospitalized COVID‐19 patients using the available published non‐randomized studies. Methods: Google Scholar, PubMed, Scopus, the Cochrane Library and Clinical Trials.gov were searched for relevant studies. A meta‐analysis of adjusted and unadjusted estimates was performed. The relative risk was used as a measure of effect. The random‐effects model was used to pool estimates using the generic inverse variance method. Results: Sixteen studies were included in the quantitative data synthesis. Results showed a statistically significant association between AC and mortality (RR = 0.56, 95% CI 0.36; 0.92, p = 0.02). Both therapeutic (Relative risk [RR] = 0.4, 95% CI 0.27; 0.57) and prophylactic AC (RR = 0.54, 95% CI 0.41; 0.71) were associated with lower risk of mortality. Pre‐admission AC was not associated with mortality (RR = 0.84, 95% CI 0.49; 1.43, p > 0.05) while prophylactic AC was associated with higher risk of mortality compared to therapeutic AC (RR = 1.58, 95% CI 1.34; 1.87, p < 0.001). Conclusion: Findings support the association of AC with mortality in Covid‐19 patients. The results, synthesized from mostly low‐quality studies, show that prophylactic and therapeutic AC might reduce mortality in Covid‐19 patients. Findings suggest that therapeutic doses might be associated with better survival compared to prophylactic doses.