ABSTRACT: The severity of lung involvement is the main prognostic factor in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Carbohydrate antigen 15-3 (CA 15-3), a marker of lung damage and fibrosis, could help predict the prognosis of SARS-CoV-2 pneumonia. This was a retrospective and observational study. CA 15-3 was analyzed in the blood samples of patients consecutively admitted for SARS-CoV-2 pneumonia and whose blood samples were available in the biobank. Other prognostic markers were also measured (interleukin 6 [IL6], C-reactive protein [CRP], D-dimer, troponin T, and NT-ProBNP). The occurrence of in-hospital complications was registered, including death, the need for medical intensive care, and oxygen therapy at discharge. In this study, 539 patients were recruited (54.9% men, mean age: 59.6 ± 16.4 years). At admission, the mean concentrations of CA 15-3 was 20.5 ± 15.8 U/mL, and the concentration was correlated with male sex, older age, and other severity markers of coronavirus disease of 2019 (COVID-19) (IL6, CRP, D-dimer, troponine T, and NT-ProBNP). CA 15-3 levels were higher in patients who died (n = 56, 10.4%) (35.33 ± 30.45 vs. 18.8 ± 12.11, p < 0.001), who required intensive medical support (n = 78, 14.4%; 31.17 ± 27.83 vs. 18.68 ± 11.83; p < 0.001), and who were discharged with supplemental oxygen (n = 64, 13.3%; 22.65 ± 14.41 vs. 18.2 ± 11.7; p = 0.011). Elevated CA 15-3 levels (above 34.5 U/mL) were a strong predictor of a complicated in-hospital course, in terms of a higher risk of death (adjusted odds ratio [OR] 3.74, 95% confidence interval [CI]: 1.22-11.9, p = 0.022) and need for intensive care (adjusted OR 4.56, 95% CI: 1.37-15.8) after adjusting for all other risk factors. The degree of lung damage and fibrosis evaluated in terms of CA 15-3 concentrations may allow early identification of the increased risk of complications in patients with SARS-CoV-2 pneumonia.
