Impact of Thromboprophylaxis Intensity on Patients' Mortality Among Hospitalized Patients with COVID-19: A Propensity-Score Matched Study

Purpose: Venous thromboembolism (VTE), a major complication that has been reported in patients with COVID-19, is associated with an increased risk of mortality. The purpose of this study was to compare in-hospital mortality among hospitalized patients with COVID-19 who received high-intensity versus standard-intensity thromboprophylactic anticoagulation. Patients and Methods: A secondary database analysis was conducted using data for adult patients who were hospitalized for COVID-19 in Saudi Arabia and received enoxaparin for thromboprophylaxis during their hospitalization. While enoxaparin 40 mg daily is considered the standard-intensity, doses higher than the standard but not to reach the therapeutic dose were considered as high-intensity. The primary outcome in the study was in-hospital mortality, and the secondary outcomes included intensive care unit (ICU) and hospital length of stay. Chi-square and t-tests were used to assess the difference between the two independent groups, and propensity score matching was performed to adjust for baseline characteristics. Results: From 3508 patients who received high- or standard-intensity enoxaparin, 1422 patients, 711 in each group, were included in the analyses after propensity score matching. The mean age of the participants was 57.2 years, and around 30% of them were female. About 72% of the patients were admitted to the ICU. No difference was observed between the two groups in the in-hospital mortality outcome (36% vs 33.5% in the high-intensity and the standard group, respectively; RR=1.06, 95% CI 0.95-1.18). However, patients who received high-intensity thromboprophylaxis had a significantly longer duration of hospitalization (15.6 days vs 13.6 days; p=0.003) and ICU stay (12.3 days vs 10.8 days; p=0.039) compared to patients who received the standard dose. Conclusion: The use of high-intensity thromboprophylaxis was not associated with a reduction in mortality. Therefore, our results do not support the routine use of high-intensity prophylactic anticoagulation in both ICU and non-ICU patients with COVID-19.