Associations of multiple plasma metals with atherosclerosis risk in mid-aged and elderly population from routine physical examination in a hospital of Shenzhen

Background Metal exposure is associated with the risk of atherosclerosis (AS), but current conclusions about the associations between exposure to multiple metals and AS remain controversial.

Objective This study aims to investigate the associations of multiple metal exposure levels with the risk of AS among a mid-aged and elderly population from routine physical examination in Shenzhen, China.

Methods A total of 664 mid-aged and elderly participants were recruited from population who ordered routine physical examination in the Eighth Affiliated Hospital, Sun Yat-Sen University of Shenzhen, China from 2012 to 2017. Information including demographic characteristics, lifestyles, physiological and biochemical indexes of the participants were collected through questionnaires and physical examinations. The concentrations of 13 metals in plasma were measured by inductively coupled plasma mass spectrometry (ICP-MS). Carotid intima-media thickness was measured by color Doppler ultrasound to evaluate AS. Logistic regression models and restricted cubic spline models were conducted to evaluate the associations and the dose-response relationships between multiple plasma metal levels and AS.

Results The average age of the participants was (64.41±7.23) years, 52.26% (347/664) were males, and the prevalence of AS was 45.33%. After adjusting for confounding factors, the single-metal logistic regression models showed that referenced with the first quartile of each metal, the ORs (95% CIs) for the fourth quartiles of plasma iron, selenium, and cadmium were 0.50 (0.29-0.88), 0.59 (0.36-0.96), and 0.54 (0.33-0.90), respectively, and the OR (95%CI) for the third quartile of thallium was 1.75 (1.08-2.83). Further multi-metal stepwise logistic regression models indicated that referenced with the first quartile of each metal, the OR (95% CI) for the fourth quartile of iron was 0.47 (0.28-0.79), and it was 1.81 (1.11-2.99) for the third quartile of thallium; with increase in concentration of plasma thallium, AS risk was gradually increased (P_trend=0.046). Moreover, the restricted cubic spline model revealed that AS risk declined with increased level of plasma iron, and a non-linear and inverse dose-response relationship was observed between them (P for non-linearity=0.043, P for overall association=0.022).

Conclusion Elevated plasma iron may be associated with a lower risk of AS, and higher plasma thallium may be associated with a higher risk of AS.