The Predictive Value of Complete Blood Count Parameters in the Clinical Course of Acute Bronchiolitis: A Descriptive Study

Objective: Bronchiolitis is an inflammation of the bronchioles, commonly caused by viral pathogens, and is characterized by respiratory distress in children under the age of two. Early identification of disease severity is critical to initiate timely treatment and prevent clinical deterioration. This study aimed to investigate whether neutrophil/lymphocyte ratio (NLR), platelet/lymphocyte ratio (TLR), mean platelet volume (MPV), and platelet mass index (PMI)-parameters derived from complete blood count-could serve as early biomarkers for diagnosis and clinical severity of the disease. Material and Methods: Patients were divided into three groups based on disease severity: outpatients (mild bronchiolitis), hospitalized patients (moderate bronchiolitis), and patients admitted to the pediatric intensive care unit (severe bronchiolitis). Age-matched healthy children with complete blood counts obtained during the same period were included as controls. Differences in CBC parameters (NLR, TLR, MPV, and PMI) at admission were compared among the groups. Results: NLR and TLR values were significantly higher in bronchiolitis patients compared to healthy controls (p<0.001). Furthermore, these values were significantly elevated in the severe bronchiolitis group compared to the mild and moderate groups (p<0.001). A statistically significant positive correlation was found between bronchiolitis severity and NLR (rho=0.460; p<0.001) and TLR (rho=0.349; p<0.001). MPV was significantly higher in healthy controls than in patients (p<0.001), while PMI showed no significant difference among the groups. Conclusion: This study demonstrates that complete blood count parameters, particularly NLR and TLR, may serve as early biomarkers to predict disease severity in patients with acute bronchiolitis.