Prediction of 10-year risk for recurrent atherosclerotic cardiovascular events in a secondary prevention population: Insights from CHART-2 and Suita studies in the Japanese population

Abstract Background Despite the European Society of Cardiology (ESC) guidelines advocating risk prediction models for secondary prevention in established atherosclerotic cardiovascular disease (ASCVD) patients, such models for Japanese individuals remain limited, owing to their comparatively lower ASCVD risk than Western populations. Given this gap, there is a need to develop tailored risk assessment tools for Japanese ASCVD patients to optimize secondary prevention strategies. Purpose Leveraging data from two large-scale, long-term cardiovascular cohorts in Japan, our aim was to develop and externally validate a 10-year risk model predicting recurrent cardiovascular events among patients with established ASCVD. Methods The CHART-2 and Suita studies, large-scale prospective observational multicenter cohort studies in Japan, served as the primary data sources for this investigation. From the CHART-2 study, which comprised 3,560 patients with a history of coronary artery disease or ischemic stroke, we derived our risk model. External validation was conducted using data from the Suita study, which included 445 patients with similar ASCVD backgrounds. The primary outcome of interest was a composite endpoint encompassing cardiovascular death, myocardial infarction, or stroke. Variable selection was performed based on clinically relevant factors previously employed in established risk scores (SMART, REACH, and TRS 2°P risk scores). Logistic regression was utilized for model development, and the predictive performance was assessed using the C-index. Results Over a median follow-up of 10.1 years, the derivation cohort experienced 756 cardiovascular events. Patients in the derivation cohort had an average age of 68.9 ± 10.6 years, with 91% and 24% having a history of coronary artery disease and ischemic stroke, respectively. Using logistic regression, the multivariate model revealed a higher recurrent risk associated with several factors including age, smoking status, systolic blood pressure, diabetes, renal function, number of ASCVD events, atrial fibrillation, lipid levels, left ventricular systolic dysfunction, and statin use. A simple risk score based on these predictors demonstrated a >5-fold gradient of 10-year recurrent risk with a C-index of 0.65 (95% CI 0.63-0.68, Figure). The prediction model was externally validated in the Suita study wit 245 cardiovascular events and a median follow-up of 10.4 years, showing good discriminative ability with a C-index of 0.64 (95% CI 0.60–0.68). Conclusion Our newly developed prediction model offers a valuable tool for identifying individuals at heightened risk of recurrent cardiovascular events over a 10-year period, thereby facilitating more targeted and effective secondary prevention strategies tailored to the unique characteristics of Japanese ASCVD patients.