Blood myxovirus resistance protein‐1 measurement in the diagnostic work‐up of suspected COVID‐19 infection in the emergency department

INTRODUCTION: Myxovirus resistance protein 1 (MxA) is a biomarker that is elevated in patients with viral infections. The goal of this study was to evaluate the diagnostic value of MxA in diagnosing COVID‐19 infections in the emergency department (ED) patients. METHODS: This was a single‐center prospective observational cohort study including patients with a suspected COVID‐19 infection. The primary outcome of this study was a confirmed COVID‐19 infection by RT‐PCR test. MxA was assessed using an enzyme immunoassay on whole blood and receiver operating chart and area under the curve (AUC) analysis was conducted. Sensitivity, specificity, negative predictive value, and positive predictive value of MxA on diagnosing COVID‐19 at the optimal cut‐off of MxA was determined. RESULTS: In 2021, 100 patients were included. Of these patients, 77 patients had COVID‐19 infection and 23 were non‐COVID‐19. Median MxA level was significantly higher (p < .001) in COVID‐19 patients compared to non‐COVID‐19 patients, respectively 1933 and 0.1 ng/ml. The AUC of MxA on a confirmed COVID‐19 infection was 0.941 (95% CI: 0.867–1.000). The optimal cut‐off point of MxA was 252 ng/ml. At this cut‐off point, the sensitivity of MxA on a confirmed COVID‐19 infection was 94% (95% CI: 85%–98%) and the specificity was 91% (95% CI: 72%–99%). CONCLUSION: MxA accurately distinguishes COVID‐19 infections from bacterial infections and noninfectious diagnoses in the ED in patients with a suspected COVID‐19 infection. If the results can be validated, MxA could improve the diagnostic workup and patient flow in the ED.