Pretreatment Coronary Artery Involvement in an Infant-Enriched Kawasaki Disease Cohort: Timing-Adjusted Analysis and Internal Model Validation

Coronary artery involvement (CAI) in Kawasaki disease (KD) is time-dependent, yet some published risk models combine pretreatment findings with variables that become known only after therapy. This retrospective single-center study examined admission-available factors associated with CAI present before intravenous immunoglobulin (IVIG) in an infant-enriched cohort and internally evaluated a timing-adjusted model. Children treated at Qingdao Women and Children's Hospital from January 2022 through December 2025 were eligible when pretreatment clinical data, laboratory measurements, and stored echocardiograms were available. Two pediatric cardiologists, blinded to clinical data and coronary classification, remeasured the left main coronary artery (LMCA), proximal left anterior descending artery (LAD), and proximal right coronary artery (RCA). Dallaire Z-scores were calculated, and CAI was defined as a maximum pretreatment Z-score of at least 2.0. The full model included age, illness day at echocardiography, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), platelet count, and extremity changes; complete/incomplete KD status and IVIG resistance were excluded from candidate predictors to reduce incorporation and temporal bias. Among 216 patients (median age, 5.7 months), 44 (20.4%) had pretreatment CAI. In the parsimonious model, CRP (adjusted odds ratio [aOR] per 10 mg/L, 1.151; 95% confidence interval [CI], 1.031-1.286), ESR (aOR per 10 mm/h, 1.158; 95% CI, 1.001-1.339), and illness day (aOR per day, 1.130; 95% CI, 1.020-1.252) were retained. The apparent area under the receiver operating characteristic curve was 0.745 and decreased to 0.710 after 1,000 bootstrap resamples; the bootstrap-corrected calibration slope was 0.82. At the data-derived threshold, the positive predictive value was 37.8%, and the negative predictive value was 92.1%. Extremity changes were not independently associated after adjustment for timing. The model showed moderate, cohort-specific performance and should not be used as a stand-alone test or substitute for echocardiography. Independent validation is required before clinical application.