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COVID-19 is a viral prothrombotic respiratory infection. Heparins exert antithrombotic and anti-inflammatory effects, and might have antiviral properties. We aimed to investigate whether thromboprophylaxis with enoxaparin would prevent untoward hospitalisation and death in symptomatic, but clinically stable outpatients with COVID-19.OVID was a randomised, open-label, parallel-group, investigator-initiated, phase 3 trial and was done at eight centres in Switzerland and Germany. Outpatients aged 50 years or older with acute COVID-19 were eligible if they presented with respiratory symptoms or body temperature higher than 37·5°C. Eligible participants underwent block-stratified randomisation (by age group 50-70 vs70 years and by study centre) in a 1:1 ratio to receive either subcutaneous enoxaparin 40 mg once daily for 14 days versus standard of care (no thromboprophylaxis). The primary outcome was a composite of any untoward hospitalisation and all-cause death within 30 days of randomisation. Analysis of the efficacy outcomes was done in the intention-to-treat population. The primary safety outcome was major bleeding. The study was registered in ClinicalTrials.gov (NCT04400799) and has been completed.At the predefined formal interim analysis for efficacy (50% of total study population), the independent Data Safety Monitoring Board recommended early termination of the trial on the basis of predefined statistical criteria having considered the very low probability of showing superiority of thromboprophylaxis with enoxaparin for the primary outcome under the initial study design assumptions. Between Aug 15, 2020, and Jan 14, 2022, from 3319 participants prescreened, 472 were included in the intention-to-treat population and randomly assigned to receive enoxaparin (n=234) or standard of care (n=238). The median age was 57 years (IQR 53-62) and 217 (46%) were women. The 30-day risk of the primary outcome was similar in participants allocated to receive enoxaparin and in controls (8 [3%] of 234 vs 8 [3%] of 238; adjusted relative risk 0·98; 95% CI 0·37-2·56; p=0·96). All hospitalisations were related to COVID-19. No deaths were reported during the study. No major bleeding events were recorded. Eight serious adverse events were recorded in the enoxaparin group versus nine in the control group.These findings suggest thromboprophylaxis with enoxaparin does not reduce early hospitalisations and deaths among outpatients with symptomatic COVID-19. Futility of the treatment under the initial study design assumptions could not be conclusively assessed owing to under-representation of older patients and consequent low event rates.SNSF (National Research Programme COVID-19 NRP78: 198352), University Hospital Zurich, University of Zurich, Dr-Ing Georg Pollert (Berlin), Johanna Dürmüller-Bol Foundation.

Die schweizweite, klinische OVID-Studie untersucht Wirksamkeit und Sicherheit von Enoxaparin bei ambulanten Patienten mit SARS-CoV-2-Infektion. Informationen zu Studienablauf und Rekrutierung von Patienten.

L’etude clinique suisse OVID porte sur l’efficacite et la securite de l’enoxaparine chez les patients ambulatoires atteints d’une infection par le SARS-CoV-2. Informations sur le protocole de l’etude et le recrutement des patients.

Background Patients with postthrombotic syndrome (PTS) treated with stents are at risk of stent thrombosis (ST). The incidence of ST in the presence and absence of anticoagulation therapy (AT) is unknown. Risk factors are not well understood. Patients and Methods From the prospective Swiss Venous Stent registry, we conducted a subgroup analysis of 136 consecutive patients with PTS. Incidence of ST was estimated from duplex ultrasound or venography, and reported for the time on and off AT. Baseline, procedural, and follow-up data were evaluated to identify factors associated with ST. Results Median follow-up was 20 (interquartile range [IQR] 9–40) months. AT was stopped in 43 (32%) patients after 12 (IQR 6–14) months. Cumulative incidence of ST was 13.7% (95% confidence interval [CI] 7.8–19.6%) and 21.2% (95% CI 13.2–29.2%) during the first 6 and 36 months, respectively. The time-adjusted incidence rate was 11.2 (95% CI 7.7–16.2) events per 100 patient-years, 11.3 (95% CI 7.3–17.3) for the period on, and 11.2 (95% CI 5.3–23.6) for the period off AT. May–Thurner syndrome (MTS) was associated with decreased incidence of ST (hazard ratio [HR] 0.37, 95% CI 0.15–0.91), whereas age Conclusion The 6-month incidence of ST was considerably high. Beyond 6 months, consecutive annual incidence rates persisted at 4.1 and 3.4% per year thereafter. Patients with higher incidence of ST were younger, had stents below the common femoral vein, postthrombotic leg inflow veins, and less often MTS. Incidence rates for the period on and off AT must be interpreted with caution. Clinical Trial Registration The study is registered on the National Institutes of Health Web site (ClinicalTrials.gov; identifier NCT02433054).