Prognostic factors in hospitalized patients with COVID-19 pneumonia and effectiveness of prophylactic anticoagulant therapy: a single-center retrospective study

Background COVID-19 pneumonia patients encounter the potential risk of venous thromboembolism (VTE) and mortality during hospitalization. This study aimed to analyzed risk factors of all-cause mortality in hospitalized patients with COVID-19 pneumonia, and investigated the effectiveness of prophylactic anticoagulation and hospital stays on the mortality in hospitalized patients with nonVTE. Methods We retrospectively analyzed all COVID-19 pneumonia patients who were admitted to our medical center from December 2022 to January 2023. Clinical data and outcome events were collected from patients' electronic medical records. Cox regression was used to identify poor prognostic factors of COVID-19 pneumonia patients with VTE and nonVTE. Landmark analysis was conducted to identify time points of hospital stays between anticoagulation treatment and in-hospital survival outcomes in COVID-19 pneumonia patients with nonVTE. Binary logistic regression analysis was performed to investigate factors related to prolonged hospital stays. Results Among 2,520 COVID-19 pneumonia patients, 1047 received prophylactic anticoagulation and 76 complicated with VTE during hospitalization. Survival curve analysis showed no statistically significant difference in mortality between COVID-19 pneumonia patients with VTE and nonVTE in prophylactic anticoagulant group (P = 0.63). Multivariate cox regression analysis revealed that male(HR = 1.398, 95%CI= [1.021,1.915]), BMI (HR = 0.935, 95%CI= [0.900,0.972]), lymphocytes (HR = 0.576, 95%CI= [0.409,0.809]), platelets (HR = 0.997, 95%CI= [0.995,0.999]), albumin (HR = 0.950, 95%CI= [0.926,0.975]), lactate dehydrogenase (HR = 1.001, 95%CI= [1.001,1.002]) were risk factors for mortality in COVID-19 pneumonia patients with nonVTE, while sCRP (HR = 1.010, 95%CI= [1.004,1.015]), anticoagulant therapy (HR = 0.247, 95%CI= [0.096,0.632]) were risk factors for mortality in COVID-19 pneumonia patients with VTE. Landmark analysis showed that for the hospital stays of 11 days, the difference in the impact of prophylactic anticoagulation on mortality was statistically significant in COVID-19 pneumonia patients with nonVTE (<= 11days, P = 0.014; > 11days, P = 0.01). CVD (OR = 1.717, 95%CI= [1.248,2.363]), CRD (OR = 1.605, 95%CI= [1.133,2.274]), sCRP (OR = 1.003, 95%CI= [1.000,1.006]), Alb (OR = 0.959, 95%CI = [0.932,0.987]) and use of glucocorticoid (OR = 1.428, 95%CI= [1.057,1.930]) were independent factors associated with hospital stays > 11 days in anticoagulant group. Conclusions This study indicated that Male, lower BMI, peripheral blood lymphocytes, platelets, albumin and elevated lactate dehydrogenase were associated with poor hospitalisation outcomes in COVID-19 pneumonia patients with nonVTE. As for COVID-19 pneumonia patients with VTE, poor hospitalisation outcomes were associated with elevated sCRP levels and no given anticoagulant therapy. No significant difference in mortality between hospitalized COVID-19 pneumonia patients with VTE and nonVTE when receiving prophylactic anticoagulation. Prolonged hospital stays (> 11 days) may limit the effectiveness of prophylactic anticoagulation on lower in-hospital mortality for COVID-19 pneumonia patients with nonVTE.