To investigate the relationship of serum 25-hydroxyvitamin D₃ [25-(OH) D₃], annexin A2 (ANXA2), acute physiology and chronic health evaluation Ⅱ (APACHE Ⅱ) scores with disease severity and prognosis of children with bronchopneumonia.

Total of 356 children with bronchopneumonia in the Children’s Diagnosis and Treatment Center of Xuzhou Central Hospital from January 2023 to January 2024 were selected. According to the severity of the disease, the patients were divided into mild group (175 cases), moderate group (101 cases) and severe group (80 cases). After treatment, patients were categorized into good prognosis group (292 cases) and poor prognosis group (64 cases). The serum 25-(OH) D₃, ANXA2 and APACHE Ⅱ scores of patients in different groups were compared, and the correlations between the above three indicators and the disease severity of children with bronchopneumonia were analyzed by Spearman correlation analysis. Whether the above three indicators were risk factors for poor prognosis in children with bronchopneumonia were determined by multivariate Logistic analysis. The predictive value of the three indicators alone and combination for poor prognosis in children with bronchopneumonia were analyzed by receiver operating characteristic (ROC) curve. The goodness of fit of the risk model were tested by Hosmer-Lemeshow method.

At admission, the serum 25-(OH) D₃ of children in the severe group [(33.25±12.35) nmol/L] was significantly lower than those of children in moderate group and mild group [(54.63±13.16) nmol/L, (68.98±15.27) nmol/L]; However, the ANXA2 and APACHE Ⅱ scores [(4.81±1.25) μmol/L, (18.25±6.98) scores] were significantly higher than those of moderate condition group [(4.07±0.89) μmol/L and (13.63±4.21) scores] and mild condition group [(3.22±0.64) μmol/L and (8.74±2.32) scores], with significant differences (all P<0.001). Spearman correlation analysis showed that serum 25-(OH) D₃ was negatively correlated with the severity of the disease (r_s =-0.626, P<0.001), while ANXA2 and APACHE Ⅱ score were positively correlated with the severity of the disease (r_s=0.434, 0.490, both P<0.001). The serum 25-(OH) D₃ of children in poor prognosis group [(62.45±12.78) nmol/L] was lower than that of good prognosis group [(93.16±18.93) nmol/L]. The ANXA2 and APACHE Ⅱ scores [(4.92±1.23) μmol/L and (12.36±3.84) scores] were significantly higher than those of good prognosis group [(3.11±0.87) μmol/L and (5.63±1.28) scores], with significant differences (all P<0.001). Logistic multivariate regression analysis showed that serum 25-(OH) D₃ (OR=0.955, 95%CI: 0.936-0.975, P<0.001), ANXA2 (OR=3.817, 95%CI: 2.535-5.748, P<0.001) and APACHE Ⅱ score (OR=2.079, 95%CI: 1.523-2.839, P<0.001) were all the main influencing factor for the prognosis of children with bronchopneumonia. ROC curve analysis showed that the AUC of the combined prediction of poor prognosis in children with bronchopneumonia by serum 25-(OH) D₃, ANXA2 and APACHE Ⅱ score was 0.895 (95%CI: 0.858-0.947), and the sensitivity and specificity were 85.90% and 80.80%, respectively. Meanwhile, the DeLong test revealed that the performance of the combined prediction model was superior to that of individual indicator of serum 25-(OH) D₃, ANXA2 or APACHE Ⅱ score (Z=5.275, P<0.001; Z=4.211, P<0.001; Z=2.505, P=0.033). Hosmer-Lemeshow result showed a relative high predictive efficacy (χ²=10.347, P=0.242).

Low serum 25-(OH) D₃, high ANXA2 and high APACHE Ⅱ scores are closely related to the severity and prognosis of children with bronchoponia. It is of certain guiding significance to pay attention to the changes of the above indicators in the treatment of children with bronchopneumonia.