Objective To investigate the correlations of serum levels of endothelial cell-specific molecule-1 (ESM-1, also known as endocan), interleukin (IL)-1α, and human chondroglycan protein-39 (also known as YKL-40) with disease severity and prognosis in children with recurrent respiratory infections (RRI).

Methods A total of 86 children with RRI were prospectively enrolled as case group and divided into mild (37 cases), moderate (31 cases), and severe (18 cases) groups based on disease severity, and divided into good prognosis (64 cases) and poor prognosis (22 cases) groups based on prognosis. Additionally, 94 healthy children who underwent physical examinations during theYKL-40 were measured using enzyme-linked immunosorbent assay (ELISA) in all children. Spearman′s correlation analysis was used to assess the correlation between serum levels of endocan, IL-1α, and YKL-40 and disease severity in children with RRI. Multivariate Logistic regression analysis was conducted to explore the factors influencing the prognosis of children with RRI. Receiver operating characteristic (ROC) curves were used to evaluate the predictive value of serum endocan, IL-1α, and YKL-40 for the prognosis of children with RRI.

Results The serum levels of endocan, IL-1α, and YKL-40 in the case group were higher than those in the control group (P < 0.05). The serum levels of endocan, IL-1α, and YKL-40 in the moderate and severe groups were higher than those in the mild group, and the levels in the severe group were higher than those in the moderate group (P < 0.05). The serum levels of endocan, IL-1α, and YKL-40 in the poor prognosis group were higher than those in the good prognosis group (P < 0.05). Serum levels of endocan, IL-1α, and YKL-40 were significantly positively correlated with disease severity in children with RRI (r=0.407, 0.493, 0.452, respectively; P < 0.001). Multivariate Logistic regression analysis showed that serum endocan(OR=1.412), IL-1α(OR=1.583), and YKL-40(OR=1.259) were independent influencing factors for the prognosis of children with RRI (P < 0.05). The ROC curve showed that the area under the curve for the combined prediction of poor prognosis in children with RRI by serum endocan, IL-1α, and YKL-40 was 0.925, which was significantly larger than that for endocan, IL-1α, and YKL-40 alone.

Conclusion Serum levels of endocan, IL-1α, and YKL-40 are closely related to disease severity and prognosis in children with RRI, and their combined detection has high predictive value for the prognosis of children with RRI.