Blood pressure-stratified associations of the atherogenic index of plasma with all-cause mortality: a 10-year rural cohort study in China.

OBJECTIVE: Although the role of AIP in predicting cardiovascular disease has been recognized, its association with all-cause mortality in different blood pressure status populations remains unclear. This study aims to investigate the predictive ability of the Atherogenic Index of Plasma (AIP) and its modified indices for all-cause mortality in rural low-income populations with different blood pressure statuses and compare them with the Triglyceride-Glucose (TyG) index.

METHODS: A total of 3,924 rural low-income participants were included in this study. Sociodemographic variables, lifestyle habits, anthropometric measurements, and biochemical markers were systematically recorded. Cox regression and restricted cubic spline (RCS) analyses were used to explore the linear and non-linear associations between TyG and AIP and their modified indices (TyG-BMI, TyG-WHtR, TyG-WC, TyG-WWI, AIP-BMI, AIP-WHtR, AIP-WC, AIP-WWI) and all-cause mortality. Kaplan-Meier survival curves were plotted. Time-dependent receiver operating characteristic (ROC) curves were constructed separately in the hypertensive and non-hypertensive groups to evaluate and compare the predictive ability of TyG and AIP and related indices for all-cause mortality. Additionally, subgroup analyses were performed based on age, gender, and blood glucose status, and mediation analyses were conducted for fasting blood glucose and LDL.

RESULTS: During a median follow-up of 8.82 years, 1,024 cases of all-cause mortality were recorded. After adjusting for confounders, in the hypertensive group, TyG and AIP and their modified indices were significantly negatively associated with all-cause mortality (all P < 0.001). Among these, the AIP and its modified index demonstrated stronger protective associations compared to the TyG-based index. Specifically, a one-unit increase in AIP-WHtR (range: -1.47 to 1.68) was associated with a 79% reduction in the risk of all-cause mortality (HR: 0.21, 95% CI: 0.18-0.25, P < 0.001); a one-unit increase in AIP (range: -2.41 to 2.90) was associated with a 57% reduction in the risk of all-cause mortality (HR: 0.43, 95% CI: 0.39-0.47, P < 0.001). However, in the non-hypertensive group, no significant associations were observed between TyG and AIP and their modified indices and all-cause mortality (all P > 0.05). In the hypertensive group, TyG and AIP and their modified indices had a non-linear association with all-cause mortality, characterized by a rapid initial decline followed by a plateau. Compared with TyG and its modified indices, AIP and its modified indices showed better predictive ability. Subgroup analyses further confirmed the robustness of the related conclusions, and no mediating effects of fasting blood glucose and LDL were found.

CONCLUSION: AIP and its modified indices are significantly negatively associated with all-cause mortality in hypertensive individuals and have a non-linear relationship. No such association was found in the non-hypertensive group. AIP and its modified indices have better predictive ability for all-cause mortality than TyG and its modified indices. These findings provide a scientific basis for the prevention and treatment of cardiovascular diseases in rural areas.