Remnant cholesterol inflammatory index as a predictive biomarker for stroke risk in middle-aged and elderly individuals: insights from the china health and retirement longitudinal study

The present study investigated the Remnant Cholesterol Inflammatory Index (RCII), a novel biomarker integrating remnant cholesterol (RC) and high-sensitivity C-reactive protein (hs-CRP), to elucidate its association with stroke risk and explore its potential as a predictive tool among middle-aged and older adults in China. A total of 7,940 middle-aged and elderly participants from the China Health and Retirement Longitudinal Study (CHARLS) were included. The primary endpoint was stroke event occurrence. The RCII was calculated as follows: RC (mg/dL) × hs-CRP (mg/L)/10. The relationship between RCII and stroke risk across different blood glucose levels was analyzed using Kaplan–Meier curves, Cox proportional hazards models, and restricted cubic spline methods. During the follow-up period, 611 participants (7.7%) experienced a stroke. The baseline RCII and stroke occurrence had a significant positive linear relationship, where each unit increase in RCII was associated with an 11% higher stroke risk, particularly evident in individuals with impaired glucose regulation. Additionally, the RCII correlated positively with stroke risk in the middle-aged population, whereas the association was not observed in the elderly population. Mediation analysis indicated that diastolic blood pressure partially mediated the association between the RCII and stroke risk, with approximately 3.1% mediation. Baseline RCII was a potential risk factor independently associated with incident stroke, highlighting its potential to reduce stroke burden and promote healthy aging, particularly in populations with prediabetes and middle-aged individuals. This finding supported the development of targeted prevention strategies tailored to different glycemic statuses, contributing to health equity in stroke prevention.