Joint associations of atherogenic index of plasma and high-sensitivity C-reactive protein on stroke: a large-scale prospective cohort study

BACKGROUD: Although both the atherogenic index of plasma (AIP) and high-sensitivity C-reactive protein (hs-CRP) are recognized as risk markers for stroke, their combined effect has yet to be fully understood. To address this gap, we introduced the inflammatory atherogenic index (IAI), a composite measure incorporating AIP and hs-CRP, and investigated its potential in predicting stroke ris METHODS: We analyzed data from the China Health and Retirement Longitudinal Study (CHARLS). IAI was calculated using the formula: IAI = AIP × hs-CRP / 10. Cox proportional hazard models were used to estimate stroke risk associated with IAI. Mediation analysis using VanderWeele's method evaluated the mediating role of systolic and diastolic blood pressures. RESULTS: The study included 9,687 participants with a mean baseline age of 58.66 years (SD = 9.23), of whom 4,542 (46.9%) were male. Over the 7-year follow-up period, 662 incident stroke cases (6.8%) were recorded. After adjusting for all covariates, each standard deviation (SD) increase in the inflammatory atherogenic index (IAI) was linked to an 11.0% higher stroke risk (HR = 1.11, 95% CI: 1.03-1.19). A nonlinear, inverted U-shaped relationship between IAI and stroke risk was observed (P = 0.015). Mediation analysis showed that systolic and diastolic blood pressures mediated 19.64% and 25.79% of the IAI-stroke association. Hs-CRP and AIP also interacted synergistically to increase stroke risk (synergy index = 1.35, 95% CI: 1.03-1.76). CONCLUSIONS: IAI is associated with increased stroke risk, with mediation by blood pressure. This highlights the potential of IAI as a biomarker for stroke risk, with early intervention in patients with high IAI potentially reducing stroke risk.