Development and internal validation of a 5-year major cardiovascular and cerebrovascular events prediction model using a simplified carotid plaque score in a hospital-based primary-prevention cohort

Background Carotid plaque burden is an established cardiovascular risk marker, but the incremental predictive value of a simplified six-segment plaque score within a multivariable model remains less well characterized in hospital-based Chinese primary-prevention populations. We aimed to develop and internally validate a 5-year model for major adverse cardiovascular and cerebrovascular events (MACE) incorporating this score. Methods This single-center retrospective cohort included adults aged ≥40 years without prior clinical cardiovascular or cerebrovascular disease who underwent bilateral carotid ultrasonography between 2015 and 2020. Plaque presence in six carotid segments generated a 0–6 score. The primary outcome was 5-year hard MACE, defined as cardiovascular death, nonfatal myocardial infarction, or nonfatal ischemic stroke. Three Cox models were compared: clinical predictors alone, clinical predictors plus binary plaque presence, and clinical predictors plus plaque score. Performance was assessed by discrimination, calibration, Brier score, decision curve analysis, and 1,000 bootstrap resamples. Results Among 2,413 patients, 1,560 (64.6%) had carotid plaque and 108 experienced hard MACE during a median follow-up of 4.92 years. Five-year MACE incidence increased from 1.5% for plaque scores 0–1 to 6.1% for scores 2–4 and 15.4% for scores 5–6 ( P < 0.001). Each 1-point score increase was associated with higher MACE risk (HR, 1.32; 95% CI, 1.21–1.44). The apparent C-index increased from 0.753 for the clinical model to 0.804 with the plaque score; the corresponding 5-year AUC and Brier score were 0.807 and 0.0381. After bootstrap correction, the C-index was 0.792 and calibration slope 0.93. Model 3 showed greater net benefit across most 2%–10% thresholds, with broadly similar findings in sensitivity analyses. Conclusions In this hospital-based primary-prevention cohort, the simplified six-segment carotid plaque score provided incremental predictive information beyond conventional clinical factors and binary plaque presence. External validation, particularly in lower-risk community and primary-care populations, is required before broader clinical application.