Sex-specific associations between CBC-derived inflammatory markers and the prevalence of myocardial infarction in US adults

To explore the relationships between inflammatory markers obtained from complete blood count (CBC) and the prevalence of myocardial infarction (MI). A cross-sectional study was conducted using data from the National Health and Nutrition Examination Survey (NHANES) spanning 1999 to 2020. A total of 46,697 US adults were enrolled, including 1824 with self-reported physician-diagnosed MI history. Systemic inflammatory response index (SIRI) and five other CBC-derived inflammatory indices were included. Logistic regression models, restricted cubic spline analysis, and subgroup analysis were applied to examine the association between these indices and MI prevalence with adjustments for potential confounding variables. Interaction analysis was used to verify the sex-specific effect modification and mediation analysis was performed to explore the mediating role of metabolic diseases including hypertension, diabetes and dyslipidemia. After full adjustment for confounding factors, elevated SIRI, NLR, MLR, and NMLR were significantly positively associated with MI prevalence (all P < 0.001). Restricted cubic spline analysis revealed nonlinear dose–response relationships between SIRI, MLR, SII, and MI prevalence (all P for non-linearity < 0.05). Significant sex-specific heterogeneity was observed. SIRI, NLR, NMLR, and SII had markedly stronger positive correlations with MI in females than males (all P for interaction < 0.05). Mediation analysis indicated metabolic diseases mediated approximately one-quarter to one-third of the SIRI-MI history association. This study revealed a significant link between CBC-derived inflammation markers and MI prevalence, with sex acting as a key modifier. Further longitudinal research is crucial to assess the utility of these accessible, low-cost indicators in routine cardiovascular risk assessment and to clarify causal pathways.