IMPORTANCEHospitalized patients with COVID-19 are at risk for venous and arterial thromboembolism and death. Optimal thromboprophylaxis dosing in high-risk patients is unknown.OBJECTIVE To evaluate the effects of therapeutic-dose low-molecular-weight heparin (LMWH) vs institutional standard prophylactic or intermediate-dose heparins for thromboprophylaxis in high-risk hospitalized patients with COVID-19. DESIGN, SETTING, AND PARTICIPANTSThe HEP-COVID multicenter randomized clinical trial recruited hospitalized adult patients with COVID-19 with D-dimer levels more than 4 times the upper limit of normal or sepsis-induced coagulopathy score of 4 or greater from May 8, 2020, through May 14, 2021, at 12 academic centers in the US.INTERVENTIONS Patients were randomized to institutional standard prophylactic or intermediate-dose LMWH or unfractionated heparin vs therapeutic-dose enoxaparin, 1 mg/kg subcutaneous, twice daily if creatinine clearance was 30 mL/min/1.73 m 2 or greater (0.5 mg/kg twice daily if creatinine clearance was 15-29 mL/min/1.73 m 2 ) throughout hospitalization. Patients were stratified at the time of randomization based on intensive care unit (ICU) or non-ICU status. MAIN OUTCOMES AND MEASURESThe primary efficacy outcome was venous thromboembolism (VTE), arterial thromboembolism (ATE), or death from any cause, and the principal safety outcome was major bleeding at 30 ± 2 days. Data were collected and adjudicated locally by blinded investigators via imaging, laboratory, and health record data. RESULTSOf 257 patients randomized, 253 were included in the analysis (mean [SD] age, 66.7 [14.0] years; men, 136 [53.8%]; women, 117 [46.2%]); 249 patients (98.4%) met inclusion criteria based on D-dimer elevation and 83 patients (32.8%) were stratified as ICU-level care. There were 124 patients (49%) in the standard-dose vs 129 patients (51%) in the therapeutic-dose group. The primary efficacy outcome was met in 52 of 124 patients (41.9%) (28.2% VTE, 3.2% ATE, 25.0% death) with standard-dose heparins vs 37 of 129 patients (28.7%) (11.7% VTE, 3.2% ATE, 19.4% death) with therapeutic-dose LMWH (relative risk [RR], 0.68; 95% CI, 0.49-0.96; P = .03), including a reduction in thromboembolism (29.0% vs 10.9%; RR, 0.37; 95% CI, 0.21-0.66; P < .001). The incidence of major bleeding was 1.6% with standard-dose vs 4.7% with therapeutic-dose heparins (RR, 2.88; 95% CI, 0.59-14.02; P = .17). The primary efficacy outcome was reduced in non-ICU patients (36.1% vs 16.7%; RR, 0.46; 95% CI, 0.27-0.81; P = .004) but not ICU patients (55.3% vs 51.1%; RR, 0.92; 95% CI, 0.62-1.39; P = .71). CONCLUSIONS AND RELEVANCEIn this randomized clinical trial, therapeutic-dose LMWH reduced major thromboembolism and death compared with institutional standard heparin thromboprophylaxis among inpatients with COVID-19 with very elevated D-dimer levels. The treatment effect was not seen in ICU patients.

Background To characterize young adult patients hospitalized with COVID-19 and identify predictors of survival at 30 days. Methods This retrospective cohort study took place at 12 acute care hospitals in the New York City area. Patients aged 18-39 hospitalized with confirmed COVID-19 between March 1st and April 27th, 2020 were included in the study. Demographic, clinical and outcome data were extracted from electronic health record reports. Results 1013 patients were included in the study (median age, 33 years [interquartile range (IQR) 28-36]; 52% female). At the study end point, 940 (92.8%) of patients were discharged alive, 18 (1.8%) remained hospitalized, 5 (0.5%) were transferred to another acute care facility and 50 (4.9%) expired. The most common comorbidities in hospitalized young adult patients were obesity (51.2%), diabetes mellitus (14.8%) and hypertension (13%). Multivariable analysis revealed that obesity (adjusted hazard ratio [aHR], 2.71; 95% CI, 1.28-5.73; p 0.002) and Charlson Comorbidity Index score (aHR, 1.20; 95% CI, 1.07-1.35; p 0.002) were independent predictors of in-hospital 30-day mortality. Conclusion Obesity was identified as the strongest negative predictor of 30-day in-hospital survival in young adults with COVID-19.

Coronavirus disease-2019 (COVID-19) has been associated with significant risk of venous thromboembolism (VTE), arterial thromboembolism (ATE), and mortality particularly among hospitalized patients with critical illness and elevated D-dimer (Dd) levels. Conflicting data have yet to elucidate optimal thromboprophylaxis dosing. HEP-COVID (NCT04401293) is a Phase 3, multicenter, pragmatic, prospective, randomized, pseudo-blinded, active control trial to evaluate efficacy and safety of therapeutic-dose low molecular weight heparin (LMWH) versus prophylactic-/intermediate-dose LMWH or unfractionated heparin (UFH) for prevention of a primary efficacy composite outcome of VTE, ATE, and all-cause mortality (ACM) 30 ± 2 days post-enrollment. Eligible patients have COVID-19 diagnosis by nasal swab or serologic testing, requirement for supplemental oxygen per investigator judgment, and Dd >4x upper limit of normal (ULN) or sepsis-induced coagulopathy (SIC) score ≥4. Subjects are randomized to enoxaparin 1 mg/kg SQ/BID (CrCl ≥ 30 ml/min) or 0.5 mg/kg (CrCl 15-30 ml/min) vs local institutional prophylactic regimens including: a) UFH up to 22,500 IU daily (divided BID or TID), b) enoxaparin 30mg and 40mg SQ QD or BID, or c) dalteparin 2500IU or 5000 IU QD. The principal safety outcome is major bleeding. Events are adjudicated locally. Based on expected 40% relative risk reduction (RRR) with treatment-dose compared with prophylactic-dose prophylaxis, 308 subjects will be enrolled (assuming 20% drop-out) to achieve 80% power. Distinguishing design features include an enriched population for the composite endpoint anchored on Dd >4x ULN, stratification by ICU vs non-ICU, and the ability to capture asymptomatic proximal deep venous thrombosis via screening ultrasonography prior to discharge.