Role of Carcinoembryonic Antigen in Severity Assessment and Mortality Prediction in COVID-19 Patients

Background Early risk stratification of COVID-19 may yield a better prognosis by tailoring effective treatment strategies. Recent studies have identified that elevated carcinoembryonic antigen (CEA) has prognostic value in terms of disease severity and mortality in patients with pneumonia. This study aims to explore the potential of CEA as a marker for both severity assessment and mortality prediction in COVID-19 patients. Methods From August 2020 to October 2021, we conducted this observational study in which patients who tested positive for COVID-19 by reverse transcription polymerase chain reaction (RT-PCR) or had high-resolution computed tomography (HRCT) chest suggestive of COVID-19 were included on day 0 of their admission to the COVID unit. Patients were classified into mild, moderate, severe, and critical according to the World Health Organization (WHO) guidelines. Blood samples were collected for complete blood count (CBC), C-reactive protein (CRP), ferritin, and CEA on days 0, 3, 7, and 14 of admission. The patient's profile was used to obtain lactate dehydrogenase (LDH), D-dimer, and HRCT scores [based on COVID-19 reporting and data system (CO-RADS) grade]. We used receiver operating characteristic (ROC) curves with Youden's index to find the initial (day 0) critical values of CEA for each of mild, moderate, severe, and critical COVID-19. The Kaplan-Meier survival curve was used to predict mortality with the best initial (day 0) cut-off value of CEA. Results Among 75 patients in this study, 15, 20, 19, and 21 were in the mild, moderate, severe, and critical groups, respectively; most were male (68%), and mortality was 18 (24%). Spearman's rank correlation test demonstrates a strong correlation between COVID-19 severity and changes in CEA. In the ROC curves, the area under the curve (AUC) value of CEA was higher among markers in all classifications except for mild to moderate disease. The AUC and critical values of CEA were as follows: for mild to moderate (0.948), 2.5 ng/ml; moderate to severe (1.000), 6.02 ng/ml; and severe to critical (0.769), 11.75 ng/ml. The survival curve shows the best initial cut-off values for mortality outcomes: CEA ≥7.15, CRP ≥81.52, ferritin ≥680.68, lymphocyte percentage ≤7.5, and neutrophil lymphocyte ratio ≥12.7. Conclusions The initial levels of CEA can serve as markers for severity assessment and mortality outcome prediction of COVID-19.