Abstract:Objective To construct an early warning model for mycoplasma pneumoniae pneumonia (MPP) with pleural effusion in children based on serum inflammatory markers.Methods A retrospective analysis of the clinical data of 171 children with MPP and pleural effusion admitted to the hospital from July 2021 to July 2023 was conducted. The data were randomly divided into a training set (n = 137) and a validation set (n = 34) at an 8:2 ratio. During hospitalization, the children were categorized into poor prognosis and good prognosis groups. Clinical data and serum inflammatory markers [interleukin-17A (IL-17A), high mobility group box 1 (HMGB1), procalcitonin (PCT), serum amyloid A (SAA)] were compared between the poor prognosis and good prognosis groups in the training set, and the factors influencing poor prognosis in children with MPP and pleural effusion were analyzed. An early warning model for poor prognosis in children with MPP and pleural effusion was constructed and validated based on serum inflammatory markers.Results Among the 137 children in the training set, the incidence of poor prognosis was 35.77% (49/137), while among the 34 children in the validation set, it was 35.29% (12/34). In the training set,the duration of fever, hospital stay and D-dimer (D-D) in the poor prognosis group were higher than those in the good prognosis group (P < 0.05). The serum levels of IL-17A, HMGB1, PCT, and SAA were also higher in the poor prognosis group than in the good prognosis group (P < 0.05). Logistic regression analysis showed that IL-17A level [O^R = 3.951 (95% CI: 1.737, 8.988)], HMGB1 level [O^R = 5.339 (95% CI: 2.347, 12.145)], PCT level [O^R = 4.084 (95% CI: 1.795, 9.290)] and SAA level [O^R = 4.749 (95% CI: 2.088, 10.804)] were risk factors for poor prognosis in MPP patients with pleural effusion (P < 0.05).The model in the training set predicted poor prognosis in children with MPP and pleural effusion with a sensitivity of 89.80% (95% CI: 0.770, 0.962), specificity of 92.05% (95% CI: 0.838, 0.965), and an area under the curve of 0.907 (95% CI: 0.762, 0.969). The model in the validation set predicted poor prognosis with a sensitivity of 83.33% (95% CI: 0.509, 0.971), specificity of 90.91% (95%CI: 0.694, 0.984), and an area under the curve of 0.865 (95%CI: 0.717, 0.935).Conclusion Serum IL-17A, HMGB1, PCT, and SAA are related to poor prognosis in children with MPP and pleural effusion. Constructing an early warning model based on serum IL-17A, HMGB1, PCT, and SAA is helpful for early identification of the risk of poor prognosis in children with MPP and pleural effusion.