Atherogenic index of plasma, Mediterranean diet adherence, and frailty in hypertensive older adults

Frailty is a prevalent geriatric syndrome that is important for healthy aging. This study examined the association between the atherogenic index of plasma (AIP) and frailty in hypertensive older adults and further explored whether this association differed according to Mediterranean diet adherence. We analyzed data from eight NHANES cycles (2003–2018). Frailty was quantified using a validated 35-item frailty index (FI). Dietary adherence to the Mediterranean pattern was evaluated using the alternative Mediterranean diet score derived from two 24-h dietary recalls. The AIP was calculated as the base-10 logarithm of the triglyceride-to-HDL-cholesterol ratio. Survey-weighted logistic regression, restricted cubic spline, and subgroup analyses were conducted to examine the associations between Mediterranean diet, AIP levels, and frailty. Among 2902 hypertensive older adults, frailty prevalence increased across AIP tertiles (24.2% to 30.6%) and was lower among Mediterranean diet adherent participants than non-adherent participants (20.3% vs. 30.6%). Higher AIP was associated with increased odds of frailty (highest vs. lowest tertile: OR = 1.54, 95% CI: 1.19–1.99), while Mediterranean diet non-adherence was also associated with frailty (OR = 1.63, 95% CI: 1.28–2.07). Stratified analyses showed a significant association between AIP and frailty only among participants non-adherent to the Mediterranean diet (continuous AIP: OR = 1.66, 95% CI: 1.02–2.71; highest vs. lowest tertile: OR = 1.70, 95% CI: 1.26–2.28), whereas no significant association was observed among participants adherent to the Mediterranean diet. No significant interaction between AIP and Mediterranean diet adherence on frailty was observed. Higher AIP was associated with greater odds of frailty, particularly among participants with lower Mediterranean diet adherence. These findings highlight the potential importance of the AIP and Mediterranean diet in relation to frailty among hypertensive older adults.