Atherogenic index of plasma as a simple marker for NAFLD risk stratification in community-dwelling older adults: a cross-sectional study with incremental predictive value assessment

Vollständiger Abstract

Worum geht es in dieser Arbeit?

The atherogenic index of plasma (AIP), calculated as log 10 (triglycerides/HDL-C), reflects atherogenic dyslipidemia and is associated with insulin resistance. Its continuous dose-response relationship and incremental predictive value for non-alcoholic fatty liver disease (NAFLD) beyond traditional risk factors remain undefined in community-dwelling older adults—a population with a high metabolic comorbidity burden where low-cost, integrated risk markers are urgently needed. Methods From 5,783 residents aged ≥65 years without significant alcohol consumption recruited in Zhanjiang, western Guangdong (2023–2024), 4,390 were enrolled after exclusions. NAFLD was diagnosed by ultrasonography. AIP was examined using multivariable logistic regression, restricted cubic splines, subgroup analyses, and trend tests with comprehensive confounder adjustment. Incremental predictive value was assessed through a multidimensional evaluation framework comprising ROC curves, calibration, decision curve analysis, net reclassification improvement (NRI), and integrated discrimination improvement (IDI). Results NAFLD prevalence was 42.7%, rising stepwise across AIP quartiles (22.4%, 36.9%, 50.1%, 61.3%; P for trend < 0.001). Each 1-unit increment in AIP was associated with a 6.13-fold higher NAFLD risk (OR 6.13, 95% CI 4.55-8.28) after full adjustment. Restricted cubic splines revealed a strictly linear, threshold-free association (P for nonlinearity = 0.714), consistent across age, residence, hypertension, and diabetes subgroups, with a statistically significant interaction by sex (P for interaction = 0.042). Adding AIP to a baseline clinical model improved discrimination (AUC from 0.786 to 0.811), calibration, clinical net benefit, and risk reclassification (categorical NRI 0.0997, IDI 0.0487; P< 0.001). Conclusions AIP demonstrates an independent, linear relationship with NAFLD risk in community-dwelling older adults, exhibiting no discernible safe threshold. This low-cost, routine lipid-derived marker supports a “single-indicator, dual-prevention” strategy for simultaneous NAFLD screening and cardiometabolic risk stratification in primary care, challenging the conventional practice of relying solely on discrete lipid cut-offs.