A Preliminary Prognostic Model for Predicting Poor Prognosis in COVID-19 Integrating Lung Epithelial Injury (KL-6) with Routine Care Markers

Background The coronavirus disease 2019 (COVID-19) pneumonia pandemic, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has caused millions of deaths worldwide, and is still threatening our life, making profound impact on the global economy and society in every field. Exploring risk factors for poor prognosis in COVID-19 patients would help optimize clinical management and improve health outcomes. Methods Clinical characteristics and laboratory data of 144 COVID-19 patients (confirmed by SARS-CoV-2 nucleic acid or antigen testing) admitted to Xiangya Hospital of Central South University between December 2022 and February 2023 (including 103 with favorable prognosis and 41 with poor prognosis) were collected in this retrospective study. Factors such as age, serum levels of KL-6, BUN, Scr, IL-6, and CRP were analyzed using R software and the Deepwise and Beckman Coulter DxAI platform. Poor prognosis was defined as a composite endpoint of in-hospital death, ICU admission, or clinical deterioration (escalation of respiratory support) during hospitalization. Results The statistical results showed that age, serum KL-6, BUN, Scr, IL-6 and CRP levels in poor prognosis COVID-19 patients were obviously higher than that in the favorable prognosis group. Spearman correlation analysis demonstrated that serum levels of CRP (r=0.48), IL-6 (r=0.40), cTn (r=0.37), Scr (r=0.37), BUN (r=0.58), KL-6 (r=0.35) and age (r=0.20) were positively correlated with the outcome of the COVID-19 patients. Age, serum KL-6, CRP and BUN levels were identified as risk factors for poor prognosis of COVID-19. Meanwhile, KL-6 combined with BUN, CRP and age revealed good discriminative performance (AUC=0.947, sensitivity=0.842, specificity=0.898) in diagnosis of poor prognosis of COVID-19 through ROC analysis. Conclusion Our retrospective study identified age, serum KL-6, CRP, and BUN levels as reliable risk factors and preliminary prognostic indicators for poor prognosis (a composite endpoint of in-hospital death, ICU admission, or respiratory support escalation) in COVID-19.