Serum Amyloid A Protein as a useful biomarker to predict COVID-19 patients severity and prognosis

Coronavirus Disease 2019 (COVID-19) can present with different grades of severity from mild to critical. Evaluation of biomarkers predicting severity is crucial to identify patients at high risk of disease progression and poor prognosis. Serum Amyloid A (SAA) is an acute-phase protein mainly produced by the liver in response to pro-inflammatory cytokines. In this study, we investigated SAA levels at admission (T1) and after 15 days (T2) of hospitalization in two groups of patients: survivors and non-survivors. At T1, the non-survivors showed higher SAA level than survivors (74 mg/dL vs 48.75 mg/dL). At T2, the survivor group value decreased to 6.55 mg/dL, the non-survivor group still showed high levels (51.1 mg/dL). The SAA level in control group was 0.35 mg/dL. Furthermore, a cut-off value of 63 mg/dL able to discriminate survivors from non-survivors was established by ROC curve analysis at T1. At T2, the cut-off decreased to 30.9 mg/dL. A similar decreasing trend was observed for D-Dimer, hsCRP, IL-6 and procalcitonin levels. The results of this retrospective study suggest that SAA is a good marker of COVID-19 disease alone and/or in combination with other inflammatory biomarkers. Identification of reliable prognostic analytes is of great clinical relevance, as it would improve patient management besides being costs saving.