The effect of peripheral blood eosinophilia on inflammatory markers in asthmatic patients with lower respiratory tract infections

Background To investigate the behaviour of the inflammatory marker neutrophil-to-lymphocyte ratio (NLR) in the presence of peripheral blood eosinophilia (PBE) in paediatric asthma patients with lower respiratory tract (LRT) infections. Methods This retrospective study enrolled consecutive patients aged >= 5 years who were diagnosed with asthma and whose haemogram values were available. The patients were further subdivided based on the presence or absence of LRT infections and allergies. NLR and C-reactive protein (CRP) were evaluated in relation to the presence or absence of PBE (>= 4% eosinophils). Results A total of 991 patients were enrolled in the study. Patients with LRT infections had significantly higher leucocyte and neutrophil counts, a greater NLR and a higher level of CRP compared with patients without LRT infections. Overall, patients with PBE had significantly lower NLRs and CRP regardless of the presence or absence of an LRT infection. The PBE percentage showed moderate inverse correlations with NLR (r = -0.34) and CRP (r = -0.20). Conclusion The presence of PBE was significantly associated with lower NLR and CRP regardless of the presence or absence of an infectious condition.