A cross-sectional study of the association between blood cadmium and mortality among adults with myocardial infarction

Cadmium (Cd) plays a key role in the occurrence of myocardial infarction (MI). We aimed to explore the association between blood Cd levels and all-cause mortality of MI on the basis of the National Health and Nutrition Examination Survey databases. This study included 800 adults with MI to obtain blood Cd concentrations and their follow-up information. The association between Cd concentrations and mortality was analyzed using Cox regression, restricted cubic spline (RCS) models, mediation analysis, receiver operating characteristic curve, and Kaplan-Meier curves. All the patients were divided into 4 groups according to the quartiles of blood Cd levels (Q1, Q2, Q3, and Q4). Cox regression analysis with adjustment for covariates indicated that Cd was the promoting factor of mortality, and patients with higher Cd had a higher death risk. The RCS model indicated an "inverted checkmark" shaped correlation between Cd levels and mortality, and a turning point of 1.06 μg/L was found. A significant positive correlation was observed on the left of the turning point. Grouped patients by turning point into 2 groups, Kaplan-Meier analysis showed that the low-concentration group had a lower death risk than the high-concentration group. Subgroup analysis revealed that the prognostic effect of Cd was more pronounced in patients with former smoking history, and receiver operating characteristic curve showed that blood Cd had a better-predicting function in patients with MI. Blood Cd levels were significantly related to all-cause mortality in patients with MI, especially in patients with Cd < 1.06 μg/L.