Association between atherogenic index of plasma and new-onset stroke in individuals with different glucose metabolism status: insights from CHARLS

Abstract Background Circulating atherogenic index of plasma (AIP) levels has been proposed as a novel biomarker for dyslipidemia and as a predictor of insulin resistance (IR) risk. However, the association between AIP and the incidence of new-onset stroke, particularly in individuals with varying glucose metabolism states, remains ambiguous. Methods A total of 8727 participants aged 45 years or older without a history of stroke from the China Health and Retirement Longitudinal Study (CHARLS)were included in this study. The AIP was calculated using the formula log [Triglyceride (mg/dL) / High-density lipoprotein cholesterol (mg/dL)]. Participants were divided into four groups based on their baseline AIP levels: Q1(AIP≤0.122), Q2(0.1220.562). The primary endpoint was the occurrence of new-onset stroke events. The Kaplan–Meier curves, Multivariate Cox proportional hazard models, and Restricted cubic spline (RCS) analysis were applied to explore the association between baseline AIP levels and the risk of developing a stroke among individuals with varying glycemic metabolic states. Results During a median follow-up of 9 years, 734 participants (8.4%) had a first stroke event. The relative risk for stroke increased with each increasing quartile of baseline AIP levels. Kaplan–Meier curve analysis revealed a significant difference in stroke occurrence among the AIP groups in all participants, as well as in those with prediabetes mellitus (Pre-DM) and diabetes mellitus (DM) (all P-values <0.05). After adjusting for potential confounders, the prevalence of stroke was significantly higher in the Q2, Q3, and Q4 groups than in the Q1 group in all participants. The respective hazard ratios (95% confidence interval) for stroke in the Q2, Q3, and Q4 groups were 1.34 (1.05-1.71), 1.52 (1.19-1.93), and 1.84 (1.45-2.34). Furthermore, high levels of AIP were found to be linked to an increased risk of stroke in both pre-diabetic and diabetic participants across all three Cox models. However, this association was not observed in participants with normal glucose regulation (NGR) (p>0.05). Restricted cubic spline analysis also demonstrated that higher baseline AIP levels were associated with hazard ratios for stroke in all participants and those with glucose metabolism disorders. Conclusions An increase in baseline AIP levels was significantly associated with the risk of stroke in middle-aged and elderly individuals, and exhibited distinct characteristics depending on the individual’s glucose metabolism status.