Objective The purpose of this study was to explore the relationship between cadmium concentration and age-related macular degeneration(AMD) risk, and to further explore the mediating role of C-reactive protein (CRP) in mediating cadmium exposure and AMD risk.

Methods The data of people aged 40 and over who met the standard of nano-platoon in the National Health and Nutrition Survey of the United States between 2005 and 2008 were analyzed. Logistic regression and linear regression models were used to evaluate the relationship between cadmium exposure, plasma CRP and the risk of AMD. The mediating effect of plasma CRP on cadmium exposure and the risk of AMD were analyzed by mediating effect analysis.

Results A total of 5 604 participants were selected in this study, including 441 patients with AMD. Compared with participants without AMD, urinary cadmium and blood cadmium in patients with AMD were significantly higher. Multivariate Logistic regression analysis showed that after adjusting for age, sex, race, BMI, smoking and other factors, higher blood cadmium levels were significantly associated with increased risk of AMD (OR=1.59, P=0.005), and higher plasma CRP levels were associated with increased risk of AMD (OR=1.36, P=0.04). Multiple linear regression analysis showed that after adjusting for age, sex, race, BMI, smoking and other factors, urinary cadmium was positively correlated with plasma CRP level (β = 0.257, P < 0.001), and blood cadmium was positively correlated with plasma CRP level (β = 0.073, P < 0.001). Mediating effect analysis showed that plasma CRP mediated 4.01% of the association between blood cadmium concentration and the risk of AMD.

Conclusion We demonstrated that higher cadmium exposure can increase the risk of AMD. At the same time, there is a significant positive correlation between cadmium exposure and plasma CRP levels. Systemic inflammation may play an important role in the association between cadmium exposure and AMD.