Association between low eosinophil count and acute bacterial infection, a prospective study in hospitalized older adults

Abstract

BACKGROUND: The incidence of severe sepsis increases significantly with age: less than 5/1000 when aged from 50 to 54 years old (y/o) vs more than 25/1000 when aged 85 y/o and older. Eosinopenia and the CIBLE score have been proposed in critically ill adults and in internal medicine wards. This study aimed to assess whether a low eosinophil count is associated with acute bacterial infection among a hospitalized older adults population, and to find the most efficient eosinophil count cut-off to differentiate acute bacterial infection from other inflammatory states. METHODS: This is a prospective study from July 2020 to July 2022 in geriatric wards of the University Paul Brousse Hospital (Villejuif, France) including patients aged ≥ 75 y/o suffering from fever or biological inflammation. Acute bacterial infection was assessed using the French Society of Infectious Diseases guidelines. RESULTS: A total of 156 patients were included. Eighty-two (53%) patients suffered from acute bacterial infection (mean age (SD) 88.7 (5.9)). Low eosinophil count was independently associated with acute bacterial infection: OR [CI95%] 3.03 [1.04 – 9.37] and 6.08 [2.42 – 16.5] for eosinophil count 0 – 0.07 G/L and 0.07 – 0.172 G/L respectively (vs eosinophil count > 0.172 G/L). Specificity and sensitivity for eosinophil count < 0.01 G/L and CIBLE score were 84%-49% and 72%-62%, respectively with equivalent AUCs (0.66 and 0.67). CONCLUSION: Eosinophil count < 0.01 G/L is a simple, routinely used and inexpensive tool which can easily participate in antibiotic decisions for older adults. Further studies are needed to assess clinical benefits. Trial registration: The study was registered at Clinical trial.gov (NCT04363138 - 23/04/2020)