Respiratory infections, including community-acquired pneumonia (CAP), are a leading cause of death worldwide. However, research has yet to find a good biomarker that allows early prediction of the severity of the disease. Such a biomarker could help to identify high-risk patients at an early stage and thus reduce mortality through closer monitoring and early detection of complications. In a recent study, scientists led by Dr Barbara Weckler from Prof. Bernd Schmeck's working group at the German Center for Lung Research (DZL) at the Philipps University of Marburg have now investigated the eosinophil count as a possible marker for severe CAP progression. The result: eosinopenia with a lower eosinophil count of less than 50/µL is associated with more severe infections and a higher mortality rate in CAP patients.
Five sites, one question: Is the eosinophil count in blood suitable as a risk marker for community-acquired pneumonia?
Eosinophils are a subgroup of leukocytes involved in immune defence, such as fighting parasites and certain infections.
The study analysed data from 6,748 adult pneumonia patients treated in five university hospitals between 2009 and 2020. They were divided into groups with lower eosinophil counts (≤50/µL) and one with higher eosinophil counts (>50/µL). Mortality, need for ventilation, risk of sepsis, length of hospital stay and time to death in hospital were compared between these two groups.
A low eosinophil count (≤50/µL) is associated with a more severe course of the disease
In the patient group with lower eosinophil counts, in-hospital mortality, the need for ventilation and the risk of sepsis were significantly increased. In addition, patients with low eosinophil counts required more time before being discharged from the hospital. It was also noticeable that the patient group with low eosinophil counts died more quickly in the hospital.
How could the study results benefit patients?
"An eosinophil count (≤50/µL) could help predict disease severity in community-acquired pneumonia. The aim is to improve the prognosis of high-risk patients with low eosinophil potentially counts through early monitoring or therapy adjustment," says Dr. Weckler. Further research is still required for translation; for example, the mechanisms by which the eosinophil count influences the progression and outcome of CAP need to be investigated further. In addition, eosinopenia still needs to be validated as a standard predictive criterion.
Original publication: Weckler BC, Pott H, Race A, Jugkaeo N, Karki K, Ringshandl S, Seidemann C, Schöndorf I, Renz H, Fähndrich S, Jung AL, Bertrams W, Makoudjou A, Zöller D, Finotto S, Schild S, Seuchter SA, Rohde G, Trinkmann F, Greulich T, Vogelmeier CF, Schmeck B, Eosinopenia as predictor of disease severity in patients with community-acquired pneumonia: an observational study, CHEST (2024), doi: https://doi.org/10.1016/j.chest.2024.05.041.