Combined score of C-reactive protein level and neutrophil-to-lymphocyte ratio: A novel marker in distinguishing children with exacerbated asthma

Abstract

Background Both C-reactive protein (CRP) level and neutrophil-to-lymphocyte ratio (NLR) are commonly elevated in patients with asthma. It is necessary to develop a novel marker, the combined score of CRP level and NLR (C-NLR score) based on cutoff points of CRP and NLR, and apply it in asthma diagnosis. The aim of this study was to explore whether C-NLR could distinguish children with exacerbated asthma. Methods Children suffering from exacerbated asthma were regarded as the asthmatic group ( n = 86), which was divided into three groups: mild ( n = 54), moderate ( n = 17), and severe ( n = 15). The control group consisted of children without any allergic disease and infection ( n = 38). To compare CRP level and NLR between the asthmatic group and control group, a receiver-operating characteristic curve was constructed to determine area under the curve (AUC) and optimal cutoff point. Thereafter, the C-NLR score was classified as follows: C-NLR score of 2 with an elevated CRP level and high NLR, a C-NLR score of 1 with one of these abnormalities, and a C-NLR score of 0 with a normal CRP level and low NLR. The C-NLR score was then compared among different asthma groups. Results In the control group, the CRP level and NLR were 1.9 (0.5–2.6) mg/L and 1.01 (0.69–1.31), respectively. In the asthmatic group, the CRP level and NLR were 7.3 (3.2–14.2) mg/L and 3.08 (1.73–5.34), respectively, which were higher than those in the control group ( p < 0.001 for CRP and p < 0.001 for NLR). The AUC of CRP was 0.86, and the optimal cutoff point was 3.6 mg/L. The AUC of NLR was 0.86, and the optimal cutoff point was 1.72. The AUC of the C-NLR score was 0.94, and the optimal cutoff point was 1. Conclusions C-NLR, a novel inflammatory marker, was applied here for the exacerbated asthma for the first time. Our study has shown C-NLR is a promising marker to distinguish children with exacerbated asthma from healthy children.