Elevation of serum ferritin levels for predicting a poor outcome in hospitalized patients with influenza infection

Abstract Objectives There is an increasing evidence that ferritin is a key marker of macrophage activation but its potential role in influenza infection remains unexplored. The aim was to assess if hyperferritinemia (ferritin ≥500 ng/mL) could be a marker of poor prognosis in hospitalized patients with confirmed influenza A infection. Methods We prospectively recruited all hospitalized adult patients which tested positive for the influenza A rRT-PCR assay performed on respiratory samples in two consecutive influenza periods (2016-17 and 2017-18). Poor outcome was defined as the presence of at least one of the following: respiratory failure, admission to the Intensive Care Unit or in-hospital mortality. Results Among 494 patients, 68 (14%) developed poor outcome. One-hundred twelve patients (23%) had hyperferritinemia (39/68; 57% in the poor outcome group vs. 73/426; 17% in the remaining patients, p Conclusions Serum ferritin may discriminate a subgroup of patients with influenza infection with higher risk of developing poor outcome.