Prophylactic dose of low-molecular-weight heparin (LMWH) might not be sufficient to mitigate the clinical scenario in patients with COVID-19 and severe pneumonia

Background: Coronavirus disease 2019 (COVID-19) is commonly complicated with coagulopathy and prophylactic daily low-molecularweight heparins (LMWHs) are currently recommended in patients hospitalised with COVID-19 pneumonia in order to reduce the incidence to venous thromboembolism (VTE) Aims of the study were to assess the role of LMWH at prophylactic dose on the clinical progression and on the evolution of inflammation parameters in patients with COVID-19 pneumonia compared with those who did not receive prophylactic LMWH Materials and methods: Patients =18 years with SARS-CoV-2 infection diagnosed by means of RT-PCR positive on nasopharyngeal swab (at least once) and/or serology, with a radiologically confirmed pneumonia were included Primary endpoint: time from hospital admission (baseline [BL]) to invasive mechanical ventilation/orotracheal intubation/death (IV/IOT/death) Secondary endpoint: to compare the mean changes of inflammation parameters and to compare them between patients receiving LMWH at prophylactic dose and those not receiving LMWH In order to control for measured confounders, a marginal Cox regression model with inverse probability weights was used Results: Three hundred and seventy-four patients: 36% female, median (interquartile range [IQR]) age of 61 (IQR, 51 to 75) years, a median of eight days from onset of symptoms (5 to 11) to start LMWH Overall, we observed 62% of patients with >1 comorbidity and 10% of IOT and/or death;median BL PaO2/FiO2 was 339 mmHg (275 to 409) The estimated probability of IV/IOT/death at 15 days from admission, for patients receiving prophylactic LMWH was 22 1% (95% CI 15 6 to 30 8) and for those who did not receive LMWH was 5 0% (95% CI 2 3 to 10 8) The risk of IV/IOT/death in the two groups appeared to vary by PAO2/FiO2 (Table 1) Only a significant decrease of D-dimer was observed with the use of prophylactic LMWH (Table 2) Conclusions: Our results highlight that standard doses of prophylactic LMWH did not add any clinical advantage in COVID-19 pneumonia and more specifically in critically ill patients, even though some differences have been observed on the efficacy of heparin derivatives as anti-inflammatory agents These findings support the feeling that prophylactic doses of anticoagulation might not be sufficient to contrast the hypercoagulable and hyper-inflamed state established in many COVID-19 patients