A pro-thrombotic milieu and a higher risk of thrombotic events were observed in patients with CoronaVirus disease-19 (COVID-19). Accordingly, recent data suggested a beneficial role of low molecular weight heparin (LMWH), but the optimal dosage of this treatment is unknown. We evaluated the association between prophylactic vs. intermediate-to-fully anticoagulant doses of enoxaparin and in-hospital adverse events in patients with COVID-19. We retrospectively included 436 consecutive patients admitted in three Italian hospitals. Outcome according to the use of prophylactic (4000 IU) vs. higher (> 4000 IU) daily dosage of enoxaparin was evaluated. The primary end-point was in-hospital death. Secondary outcome measures were in-hospital cardiovascular death, venous thromboembolism, new-onset acute respiratory distress syndrome (ARDS) and mechanical ventilation. A total of 287 patients (65.8%) were treated with the prophylactic enoxaparin regimen and 149 (34.2%) with a higher dosing regimen. The use of prophylactic enoxaparin dose was associated with a similar incidence of all-cause mortality (25.4% vs. 26.9% with the higher dose; OR at multivariable analysis, including the propensity score: 0.847, 95% CI 0.400-0.1.792; p = 0.664). In the prophylactic dose group, a significantly lower incidence of cardiovascular death (OR 0.165), venous thromboembolism (OR 0.067), new-onset ARDS (OR 0.454) and mechanical intubation (OR 0.150) was observed. In patients hospitalized for COVID-19, the use of a prophylactic dosage of enoxaparin appears to be associated with similar in-hospital overall mortality compared to higher doses. These findings require confirmation in a randomized, controlled study.

Clinical features and natural history of coronavirus disease 2019 (COVID-19) differ widely among different countries and during different phases of the pandemia. Here, we aimed to evaluate the case fatality rate (CFR) and to identify predictors of mortality in a cohort of COVID-19 patients admitted to three hospitals of Northern Italy between March 1 and April 28, 2020. All these patients had a confirmed diagnosis of SARS-CoV-2 infection by molecular methods. During the study period 504/1697 patients died; thus, overall CFR was 29.7%. We looked for predictors of mortality in a subgroup of 486 patients (239 males, 59%; median age 71 years) for whom sufficient clinical data were available at data cut-off. Among the demographic and clinical variables considered, age, a diagnosis of cancer, obesity and current smoking independently predicted mortality. When laboratory data were added to the model in a further subgroup of patients, age, the diagnosis of cancer, and the baseline PaO2/FiO2 ratio were identified as independent predictors of mortality. In conclusion, the CFR of hospitalized patients in Northern Italy during the ascending phase of the COVID-19 pandemic approached 30%. The identification of mortality predictors might contribute to better stratification of individual patient risk.

The efficacy of hydroxychloroquine (HCQ) in treating SARS-CoV-2 infection is harshly debated, with observational and experimental studies reporting contrasting results. To clarify the role of HCQ in Covid-19 patients, we carried out a retrospective observational study of 4,396 unselected patients hospitalized for Covid-19 in Italy (February-May 2020). Patients' characteristics were collected at entry, including age, sex, obesity, smoking status, blood parameters, history of diabetes, cancer, cardiovascular and chronic pulmonary diseases, and medications in use. These were used to identify subtypes of patients with similar characteristics through hierarchical clustering based on Gower distance. Using multivariable Cox regressions, these clusters were then tested for association with mortality and modification of effect by treatment with HCQ. We identified two clusters, one of 3,913 younger patients with lower circulating inflammation levels and better renal function, and one of 483 generally older and more comorbid subjects, more prevalently men and smokers. The latter group was at increased death risk adjusted by HCQ (HR[CI95%] = 3.80[3.08-4.67]), while HCQ showed an independent inverse association (0.51[0.43-0.61]), as well as a significant influence of cluster∗HCQ interaction (p < 0.001). This was driven by a differential association of HCQ with mortality between the high (0.89[0.65-1.22]) and the low risk cluster (0.46[0.39-0.54]). These effects survived adjustments for additional medications in use and were concordant with associations with disease severity and outcome. These findings suggest a particularly beneficial effect of HCQ within low risk Covid-19 patients and may contribute to clarifying the current controversy on HCQ efficacy in Covid-19 treatment.