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 adverse outcomes, including in-hospital mortality. Simple risk stratification based on routinely 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 mortality in CAD patients receiving DAPT after PCI. In the clopidogrel-dominant practice setting 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 1600 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 = 1200) and a hold-out assessment subset (25%; n = 400). Predictors were explored using univariable and multivariable logistic regression with stepwise selection. Continuous variables were categorized using Weight of Evidence binning, and an integer point score was derived. Performance was summarized using ROC analysis, AUC, sensitivity, specificity, and accuracy. Given the small number of deaths and the data-driven modelling workflow, all performance 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 because 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 classification, platelet-reactivity triage, or antiplatelet treatment selection. Model redevelopment using event-efficient methods, resampling-based internal validation, and subsequent external validation are required before clinical implementation.