[Development and validation of a prediction score for gastrointestinal bleeding following percutaneous coronary intervention in East Asian patients with acute coronary syndrome].

Objective: To develop and validate a risk scoring system for post-percutaneous coronary intervention (PCI) gastrointestinal bleeding in East Asian patients with acute coronary syndrome (ACS) based on the Fine-Gray model. Methods: This post-hoc analysis was performed on the BleeMACS international multicenter registry study. Patients with ACS undergoing PCI from 15 hospitals across 10 countries between November 2003 and June 2014 were enrolled and stratified into the East Asian group (China and Japan) and the non-East Asian group (other countries). The Fine-Gray model was used to screen predictors and construct an integer-based risk scoring system, with LASSO competing-risk regression for sensitivity analysis. The primary endpoint was gastrointestinal bleeding within 1 year after discharge, with death treated as a competing risk event. Bootstrap resampling was applied for internal validation. Calibration performance was assessed using calibration slope, intercept, and expected-to-observed (E/O) risk ratio. Risk stratification was performed using the Aalen-Johansen cumulative incidence function curve and Gray's test. The temporal distribution of bleeding events was analyzed, and subgroup analyses were conducted according to sex, diabetes mellitus, chronic kidney disease, and dual antiplatelet therapy (DAPT) status. Results: A total of 15 401 ACS patients were enrolled, with an age of (63.6±12.7) years and 3 592 females (23.32%). There were 2 332 patients in the East Asian group and 13 069 in the non-East Asian group. The final model incorporated seven predictors: admission hemoglobin (subdistribution hazard ratio (SHR)=0.82, 95%CI 0.74-0.90), age (SHR=1.02, 95%CI 1.01-1.04), hypertension (SHR=1.57, 95%CI 1.10-2.25), history of heart failure (SHR=1.97, 95%CI 1.08-3.57), peptic ulcer (SHR=3.25, 95%CI 1.41-7.52), proton-pump inhibitor use (SHR=1.54, 95%CI 1.12-2.12), and bleeding history (SHR=1.65, 95%CI 0.98-2.78). The bootstrap-corrected C-index was 0.693 (95%CI 0.652-0.738), with a calibration slope of 0.969 and an E/O ratio of 0.99, indicating favorable overall calibration performance. Risk stratification showed that the bleeding risk in the high-risk group was 3.93 times that in the low-risk group in the overall cohort. For the East Asian group, Gray's test P=0.116, with no significant difference among risk strata. The trend of bleeding risk was consistent with that of the overall cohort, and the ratio of cumulative bleeding risk between the high-and low-risk subgroups was 2.72 in the East Asian group. During the 1-year follow-up, 160 cases of post-PCI gastrointestinal bleeding occurred. The cumulative incidence was higher in East Asian patients than in non-East Asian patients (34 cases (1.46%) vs. 126 cases (0.96%)), with a higher proportion of late bleeding events (181-365 days) (14 cases (41.2%) vs. 41 cases (32.5%)). Subgroup analyses demonstrated stable risk stratification and good calibration performance across clinical subgroups. Conclusions: The gastrointestinal bleeding risk scoring system established in this study exhibits acceptable discrimination and excellent calibration, with stable performance in East Asian populations and various clinical subgroups. East Asian ACS patients have a higher incidence of post-PCI gastrointestinal bleeding with persistent late risk, indicating the need for prolonged monitoring and individualized antithrombotic therapy strategies.