Association of the C-Reactive Protein-Triglyceride-Glucose Index (CTI) with Lower-Extremity Peripheral Artery Disease among U.S. Adults

Introduction:Peripheral artery disease (PAD) is a common yet underrecognized consequence of systemic atherosclerosis, affecting over 200 million adults worldwide and one in five older adults in the United States. PAD carries substantial morbidity, increasing the risk of major cardiovascular and limb events and contributing to declines in quality of life. Inflammation and metabolic dysfunction are key drivers of atherosclerosis. The C-reactive protein-triglyceride-glucose index (CTI) integrates these pathways. We examined whether CTI is associated with PAD in U.S. adults. Methods:National Health and Nutrition Examination Survey (NHANES) data from 1999 to 2004 were analyzed. Adults aged ≥20 years with available ankle-brachial index (ABI), fasting glucose, triglycerides, and C-reactive protein (CRP) were included. PAD was defined as ABI <0.90; individuals with ABI ≥1.40 were excluded. CTI was calculated as 0.412 × ln(CRP [mg/L]) + ln(triglycerides [mg/dL] × fasting glucose [mg/dL]/2). Logistic regression models evaluated CTI continuously and quartiles, adjusting for demographic, metabolic, and clinical covariates. Multinomial models assessed associations across ABI categories, including borderline ABI (0.90-0.99). Results:Among 5869 adults, 420 (7%) had PAD. Each 1-unit increase in CTI was associated with higher odds of PAD (aOR 1.47; 95% CI 1.25-1.75; p < 0.001). Higher CTI levels were associated with increased odds of PAD, with the strongest association observed in the highest quartile (aOR 2.07; 95% CI 1.41-3.06; p < 0.001). CTI was also linked to both borderline ABI and clinical PAD in multinomial analyses. Conclusion:Higher CTI is independently associated with PAD and may provide complementary information for vascular risk evaluation.