目的 基于肺超声及临床指标分析重症支原体肺炎（SMPP）患儿预后的影响因素，构建并评估列线图预测模型。 方法 选取2021年1月至2024年12月于浙江省人民医院毕节医院进行治疗的527例SMPP患儿为研究对象，按7∶3分为训练集（n = 368）和测试集（n = 159）。训练集根据患儿预后情况分为预后良好组（n = 315）和预后不良组（n = 53）。通过单因素和二元logistic回归分析患者肺超声及临床指标相关指标；受试者工作特征曲线（ROC）、校准曲线、决策曲线分析（DCA）评估构建的列线图预测模型。 结果 预后不良组入院治疗时发烧持续时间、高热占比、白细胞（WBC）计数、中性粒细胞绝对值、D-二聚体、乳酸脱氢酶（LDH）、实变大小与体表面积的比值（实变大小/BSA）、支气管造影为液体以及胸腔积液的占比均高于预后良好组（P < 0.05），而仅有支气管造影为空气的占比较预后良好低（P < 0.05）；治疗时发烧持续时间、中性粒细胞绝对值、D-二聚体和LDH水平以及胸腔积液为SMPP患儿不良预后发生的独立危险因素。训练集曲线下面积（AUC）为0.926（95%CI：0.870 ~ 0.982）、测试集AUC则为0.957（95%CI：0.882 ~ 1.000）。校准曲线及DCA曲线评估列线图预测模型结果显示其具有较高一致性和临床应用价值。 结论 治疗时发烧持续时间、中性粒细胞绝对值、D-二聚体和LDH水平以及胸腔积液为SMPP患儿不良预后的独立危险因素，据此构建的列线图预测模型的预测效能较佳。

Objective To identify prognostic factors in children with severe Mycoplasma pneumoniae pneumonia （SMPP） using lung ultrasound and clinical indicators， and to construct and evaluate a nomogram-based predictive model. Methods A total of 527 children with SMPP treated at Bijie Hospital of Zhejiang Provincial People's Hospital between January 2021 and December 2024 were enrolled and randomly allocated into a training set （n = 368） and a testing set （n = 159） in a 7∶3 ratio. The training set was categorized into good prognosis group （n = 315） and poor prognosis group （n = 53） based on the children's post-treatment conditions. Univariate and multivariate logistic regression analyses were performed to assess the correlation between patients' lung ultrasound and clinical indicators； receiver operating characteristic （ROC）， calibration curve， and decision curve analysis （DCA） were used to evaluate the constructed nomogram predictive model. Results The poor prognosis group had a longer duration of fever at admission， higher proportion of high fever， higher white blood cell （WBC） count， higher absolute neutrophil count， D-dimer， higher lactate dehydrogenase （LDH）， larger consolidation size to body surface area ratio （consolidation size/BSA）， liquid-bronchogram sign， and higher proportion of pleural effusion compared to the good prognosis group （P < 0.05）， while only the air-bronchogram sign was lower in the poor prognosis group （P < 0.05）； the duration of fever during treatment， absolute neutrophil count， DD dimer， LDH levels， and pleural effusion were independent risk factors for poor prognosis in SMPP children. The area under the curve （AUC） for the training set was 0.926 （95%CI： 0.870 - 0.982）， and for the test set was 0.957 （95%CI： 0.882 - 1.000）. Calibration curve and DCA curve assessment of the nomogram predictive model showed it had high consistency and clinical application value. Conclusion The duration of fever during treatment， absolute neutrophil count， DD dimer， LDH levels， and pleural effusion are independent risk factors for poor prognosis in children with SMPP， and the constructed nomogram predictive model has good predictive performance.