The Association Between Atherogenic Index of Plasma (AIP) and Ambulatory Arterial Stiffness Index (AASI) in Young and Middle‐Aged Patients Investigated for Hypertension

Background Arterial stiffness is increasingly recognized in young and middle‐aged patients with hypertension. The plasma atherogenic index (AIP) could be associated with ambulatory arterial stiffness index (AASI). Objective This study aimed to explore the AIP–AASI association and assess the ability of AIP to identify elevated arterial stiffness risk. Methods A total of 1000 newly diagnosed hypertensive outpatients (30–55 years) were enrolled from Hanzhong Central Hospital (April 2023–May 2024) in this observational study. All underwent 24‐h ambulatory BP monitoring for AASI calculation and fasting biochemical tests. Correlation analysis assessed lipid markers–AASI associations. Multivariable logistic regression and ROC analyses evaluated predictors of AASI ≥ 0.55. Results AIP was strongly positively correlated with AASI ( r = 0.670, p < 0.001), positively correlated with TG ( r = 0.529, p < 0.001), TYG ( r = 0.539, p < 0.001), LDL‐C ( r = 0.153, p < 0.001), and non‐HDL‐C ( r = 0.229, p < 0.001), and inversely correlated with HDL‐C ( r = −0.298, p < 0.001). AIP differed significantly across circadian BP dipping patterns (all p < 0.01). AASI decreased gradually from reverse dippers to extreme dippers, and the positive AIP–AASI correlation persisted in each pattern ( r = 0.599–0.683, all p < 0.001). Multivariable logistic regression showed that AIP was independently associated with AASI ≥ 0.55 (per SD: OR = 2.47, 95% CI 1.88–3.25, p < 0.001). ROC analysis indicated that AIP had excellent discriminatory power for AASI ≥ 0.55 (AUC = 0.806, 95% CI 0.779–0.833; sensitivity 84.0%, specificity 60.6%), which was superior to TG (AUC 0.761) and TYG (AUC 0.774) (both p < 0.05). Conclusions AIP is closely associated with AASI, suggesting that AIP may serve as an effective lipid‐derived marker for identifying arterial stiffness risk in young and middle‐aged patients with hypertension. Trial Registration: Chinese Clinical Trial Registry: ChiCTR2400082000