Association between a body shape index and myocardial infarction: a cross-sectional analysis of NHANES data with mediation modeling.

BACKGROUND: Myocardial infarction (MI) represents a significant global health burden. A Body Shape Index (ABSI) may indicate MI risk related to central adiposity, but large-scale evidence remains limited. OBJECTIVE: To examine the association between ABSI and MI, its mediating pathways, and subgroup variations using nationally representative data. METHODS: The significant empirical analysis examined 44,281 adults from NHANES 1999-2018, and the key Survey-weighted logistic regression could plausibly demonstrate that ABSI-MI odds ratios (ORs) reveal important patterns. Restricted cubic splines tested linearity. Mediation analysis evaluated effects of hypertension, diabetes, and hyperlipidemia. Predictive performance was evaluated using the area under the curve (AUC). Survey-weighted logistic regression assessed ABSI-MI odds ratios (ORs). Restricted cubic splines assessed linearity. Mediation analysis evaluated effects of hypertension, diabetes, and hyperlipidemia. Predictive performance was compared using AUC. RESULTS: The highest ABSI quartile was associated with 73% higher odds of MI (OR = 1.73, 95% CI 1.26-2.39) after full adjustment. A linear dose-response relationship was observed (P for nonlinearity = 0.655). Hypertension, diabetes, and hyperlipidemia mediated 80.1% of the association, with diabetes alone explaining 44.3%. Stronger associations were found in adults <65 years, women, smokers, and drinkers. In light of these findings, ABSI may suggest similar discrimination (AUC = 0.848) compared with BMI (AUC = 0.850), their combination achieved an AUC = 0.853. CONCLUSIONS: ABSI may demonstrate that it predicts MI independently and linearly in US adults. The relationship is largely mediated by metabolic conditions and is strongest among younger individuals and those with adverse lifestyle profiles. Adding ABSI to BMI may modestly improve MI risk stratification.