目的 本研究旨在分析6月龄以下川崎病（KD）患儿的临床表现、冠状动脉损害特征以及静脉注射免疫球蛋白（IVIg）无应答的独立危险因素与预测指标。方法 对2020年1月至2024年12月在医院住院治疗的435例KD患儿的资料进行回顾性分析。将所有患儿划分为0~5月龄组（6月龄以下）和6~12月龄组，0~5月龄组进一步分为不完全性KD（iKD）组与完全性KD（cKD）组。分析0~5月龄组与6~12月龄组患儿主要临床特征的差异，并比较iKD组和 cKD组的临床表型异同。运用多因素logistic回归分析0~5月龄组冠状动脉病变（CAL）和IVIg无应答的危险因素，通过受试者工作特征（ROC）曲线评估相关变量对IVIg无应答的预测价值。结果 0~5月龄组179例（41.1%），其卡疤红肿发生率、血小板计数等炎症相关指标显著高于6~12月龄组，而结膜充血等典型症状及白蛋白、血红蛋白水平显著更低，CAL发生率（47.5%）更高（均P<0.05）。0~5月龄组中iKD 73例（40.8%），典型症状更少，CAL 发生率（58.9%）和IVIg无应答率均高于cKD组（均P<0.05）。0~5月龄组多因素分析发现，卡疤红肿（OR=2.81，95%CI：1.44~5.48，P=0.002）与CAL发生呈正相关；结膜充血与IVIg抵抗呈显著负相关（OR=0.15，95%CI：0.03~0.89，P=0.036），而中性粒细胞/淋巴细胞比值（NLR）≥3.78（OR=3.17，95%CI：1.37~7.31，P=0.007）及发热持续时间≥6.5 d（OR=1.38，95%CI：1.03~1.84，P=0.029）为IVIg无应答危险因素。ROC曲线提示NLR≥3.78和发热≥6.5 d联合预测IVIg无应答的曲线下面积（AUC）为0.888，灵敏度0.867，特异度0.841。结论 0~5月龄组KD患儿大多临床表现不典型，iKD患儿CAL及IVIg无应答发生率更高。卡疤红肿与CAL的发生密切相关。NLR≥3.78联合发热≥6.5 d对IVIg无应答具有较高预测价值，结膜充血可能有助于6月龄以下IVIg无应答KD的早期识别与治疗。

Objective This study aimed to analyze the clinical manifestations, coronary artery lesion (CAL) features, and independent risk factors/predictive indicators for intravenous immunoglobulin (IVIg) non-response in infants with Kawasaki disease (KD) under 6 months of age. Methods A retrospective analysis was performed on clinical data of 435 KD infants aged 0-12 months who were hospitalized January 2020 to December 2024. Patients were stratified into the 0-5 months group (under 6 months) and 6-12 months group; the 0-5 months group was further subdivided into incomplete KD (iKD) and complete KD (cKD) subgroups. Differences in core clinical characteristics between the 0-5 months and 6-12 months groups were analyzed, and phenotypic variations between the iKD and cKD subgroups were compared. Multivariate logistic regression was used to identify risk factors for CAL and IVIg non-response in the 0-5 months group. Receiver operating characteristic (ROC) curves were constructed to evaluate the predictive efficacy of candidate variables for IVIg non-response. Results A total of 179 patients (41.1%) were included in the 0-5 month group. Compared with the 6-12 months group, the 0-5 months group exhibited a significantly higher incidence of Bacille Calmette-Guérin (BCG) scar erythema/swelling and elevated inflammation-related markers such as platelet count, alongside lower frequencies of typical KD symptoms like conjunctival hyperemia and reduced albumin/hemoglobin levels. The incidence of CAL was also higher in the 0-5 months group (47.5%; all P<0.05). Within the 0-5 months group, 73 patients (40.8%) were diagnosed with iKD, presenting fewer typical symptoms, a higher CAL incidence (58.9%), and a higher IVIg non-response rate than the cKD subgroup (all P < 0.05). Multivariate regression revealed that BCG scar erythema/swelling was independently associated with an increased risk of CAL (OR=2.81, 95% CI: 1.44-5.48, P=0.002). Conjunctival hyperemia was inversely correlated with IVIg non-response (OR=0.15, 95% CI: 0.03-0.89, P=0.036), while a neutrophil-to-lymphocyte ratio (NLR)≥3.78 (OR=3.17, 95% CI: 1.37-7.31, P=0.007) and fever duration≥6.5 days (OR=1.38, 95% CI: 1.03-1.84, P=0.029) were identified as independent risk factors for IVIg non-response. The combined model of NLR≥3.78 and fever duration≥6.5 days yielded an area under the ROC curve (AUC) of 0.888 for predicting IVIg non-response, with a sensitivity of 0.867 and specificity of 0.841. Conclusions KD infants under 6 months of age often present with atypical manifestations. iKD in this age group is associated with a higher incidence of CAL and IVIg non-response. BCG scar erythema/swelling is closely linked to CAL development. The combination of NLR≥3.78 and fever duration≥6.5 days has robust predictive value for IVIg non-response, while conjunctival hyperemia may facilitate the early identification and management of IVIg-nonresponsive KD in infants under 6 months.