Development and Preliminary Assessment of a Mortality Risk Score in Patients with Coronary Artery Disease Receiving Dual Antiplatelet Therapy After Percutaneous Coronary Intervention

Background: Patients with coronary artery disease (CAD) receiving dual antiplatelet therapy (DAPT) after percutaneous coronary intervention (PCI) remain at risk of early ad-verse outcomes, including in-hospital mortality. Simple risk stratification based on rou-tinely available variables may help identify higher-risk patients, but a limited number of outcome events constrains robust prediction-model development and validation. Aim: This exploratory study aimed to derive a preliminary, interpretable clinical score based on routinely available variables for risk stratification of all-cause in-hospital mor-tality in CAD patients receiving DAPT after PCI. In the clopidogrel-dominant practice set-ting of the participating centers, the score was conceived as a hypothesis-generating risk-enrichment framework rather than a validated treatment-selection tool or a surrogate measure of platelet reactivity. Methods: We analyzed a retrospective cohort of 1,600 adults with CAD admitted between 2022 and 2024; 36 in-hospital deaths occurred. Twenty demographic, clinical, laboratory, and instrumental variables were evaluated. The primary outcome was all-cause in-hospital mortality during the index hospitalization. For exploratory score derivation, the dataset was randomly divided into a derivation subset (75%; n = 1,200) and a hold-out assessment subset (25%; n = 400). Predictors were explored using univariable and multi-variable logistic regression with stepwise selection. Continuous variables were catego-rized using Weight of Evidence binning, and an integer point score was derived. Perfor-mance was summarized using ROC analysis, AUC, sensitivity, specificity, and accuracy. Given the small number of deaths and the data-driven modelling workflow, all perfor-mance estimates were considered preliminary rather than definitive internal validation. Results: The exploratory six-variable score included age ≥57 years, estimated glomerular filtration rate <45 mL/min/1.73 m², body mass index ≥25 kg/m², troponin I ≥100, prior myocardial infarction, and current smoking. In the derivation subset, each additional point was associated with higher odds of mortality (OR 1.39; 95% CI 1.29-1.51; p < 0.001), and the AUC was 0.654. A Youden-index threshold of approximately 6 points yielded sensitivity of 0.41, specificity of 0.80, and accuracy of 0.72. In the hold-out assessment subset, sensitivity was 0.53, specificity was 0.70, accuracy was 0.70, and AUC was 0.61. These estimates indicate modest discrimination and should be interpreted cautiously be-cause only 36 outcome events were available. Conclusions: This exploratory clinical score showed modest discrimination for all-cause in-hospital mortality and should be regarded as a preliminary, hypothesis-generating risk-stratification approach. It is not sufficiently validated for routine prognostic classifi-cation, platelet-reactivity triage, or antiplatelet treatment selection. Model redevelopment using event-efficient methods, resampling-based internal validation, and subsequent ex-ternal validation are required before clinical implementation.