Low eosinophil counts may predict infection among critically ill patients: Study

In the prospective monocentric study, a low eosinophil count was independently associated with diagnosing acute bacterial infection in 156 older inpatients in geriatric departments.

"Our study shows an independent association of low eosinophil count with acute bacterial infection among hospitalized older adults: OR 3.03 for eosinophil count 0–0.07 G/L compared to eosinophil count > 0.172 G/L," Edouard Baudouin and colleagues from France reported in their study.

"Eosinophil count < 0.01 G/L had better specificity (84%) than CIBLE score > 87, eosinophil/neutrophil ratio, eosinophil count < 0.04 G/L, and C reactive protein (CRP) 72%, 74%78% and 49% respectively."

There is a significant increase in the incidence of sepsis with age, including a high incidence of bacterial infection in older adults. The CIBLE score and eosinopenia have been proposed in critically ill adults and internal medicine wards. The research team aimed to assess whether a low eosinophil count was associated with acute bacterial infection among hospitalized older adults. They also determined the most efficient eosinophil count cut-off to differentiate acute bacterial infection from other inflammatory states.

For this purpose, they performed a prospective study from July 2020 to July 2022 in geriatric wards of the University Paul Brousse Hospital in Villejuif, France, including patients (aged 75 years or older), suffering from biological inflammation or fever. Acute bacterial infection was evaluated using biological identification and/or radiological and clinical data.

The study led to the following findings:

· Of 156 included patients, Eighty-two (53%) patients suffered from acute bacterial infection (mean age 88.7).

· Low eosinophil count was independently associated with acute bacterial infection: OR 3.03 and 6.08 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.

The findings showed that eosinophil < 0.01 G/L is a routinely used, simple and inexpensive tool that can easily participate in the medical decision to postpone antibiotic treatment.

The researchers, however, cautioned that "This result is not intended to be used as diagnosis tool nor to replace gold standard."

"However, compared to the CIBLE score or other scores that need specific calculation tools, this is a daily routine exam and may be used to avoid iatrogenic effects and overprescription in this population," they added.

"There is a need for further studies to assess the clinical benefits in a larger population," they concluded.

Reference:

Mésinèle, L., Pujol, T., Brunetti, N. et al. Association between low eosinophil count and acute bacterial infection, a prospective study in hospitalized older adults. BMC Geriatr 23, 852 (2023). https://doi.org/10.1186/s12877-023-04581-y