Low molecular weight heparin is associated with better outcomes than unfractionated heparin for thromboprophylaxis in hospitalized COVID-19 patients: a meta-analysis

This study aimed to compare the outcomes of the administration of LMWH and UFH in hospitalized COVID-19 patients.

We systematically searched several databases and included observational studies or clinical trials that compared the outcomes of the administration of LMWH and UFH in hospitalized COVID-19 patients. A total of nine studies comprising 9637 patients were included. Metanalysis showed that LMWH administration was associated with a lower in-hospital mortality and 28/30-day mortality compared with UFH administration {[relative risk (RR) 0.44; 95% confidence interval (95% CI) 0.32–0.61; I²: 87.9%] and (RR 0.45; 95% CI 0.24–0.86; I²: 78.4%), respectively}. Patient with LMWH had shorter duration of hospital and ICU length of stay compared with UFH {[weighted mean difference (WMD) −2.20; 95% CI −3.01 to −1.40; I²:0%] and (WMD −1.41; 95% CI −2.20 to −0.63; I²: 0%), respectively}. The risk of ICU admission or mechanical ventilation was lower in patients who received LMWH than in those who received UFH (RR 0.67; 95% CI 0.55–0.81; I²: 67.3%). However, there was no difference in the incidence of bleeding with LMWH compared with UFH (RR 0.27; 95% CI 0.07–1.01; I²: 64.6%).

Our meta-analysis showed that administration of LMWH was associated with better outcomes compared with UFH in hospitalized COVID-19 patients. Prospective cohorts and RCTs are urgently needed to explore the definitive effect of LMWH to provide direct high-certainty evidence.

PROSPERO registration number: CRD42021271977