The importance of immature granulocyte and immature reticulocyte fraction for the severity of acute bronchiolitis

The immature granulocyte (IG) and immature reticulocyte fraction (IRF) are new analytical parameters of the complete blood count, that have been studied as biomarkers of several inflammatory conditions. Here, our aim is to determine the effectiveness of IG and IRF percentages for the severity of acute bronchiolitis (AB). A single-center, prospective study was performed in patients who were hospitalized for acute bronchiolitis and healthy children were included as a control group. The demographic characteristics, white blood cell (WBC) count, platelet (PLT) count, eosinophil%, IG%, and IRF% values were analysed. Receiver operating characteristics (ROC) analysis was used to compare the diagnostic accuracies and predictive performances. We enrolled 168 infants in the acute bronchiolitis group and 80 in the control group. The Clinical Severity Score (CSS) showed that 48, 93, and 27 patients had mild, moderate, and severe bronchiolitis, respectively. The WBC, PLT, and IRF value were significantly higher in patients (p < 0.001). There was no difference between the patients and control group in terms of IG and eosinophil percentage. Only a positive correlation was observed between the clinical severity of the AB and IRF (p=0.003).The ROC curve analysis indicated that the IRF% cut-off point for predicting severity AB was >12.4, with a sensitivity of 53% and specificity of 88% (Areas under the curves (AUC):0.701,p<0.001). The WBC count, PLT count, and IRF value increased in the AB group. The IRF percentage can be used to predict the clinical severity of AB in children.