Association of blood cadmium levels with all-cause and cause-specific mortality among adults with non-alcoholic fatty liver disease: a prospective cohort study

Background Cadmium (Cd) accumulates in the body over time, damaging organs such as the liver, kidneys, and brain. Some researchers have suggested that elevated blood Cd levels may contribute to the onset and progression of nonalcoholic fatty liver disease (NAFLD). However, only a few studies have explored the relationship between Cd exposure and long-term health outcomes in patients with NAFLD. This study aimed to evaluate the predictive value of blood cadmium levels for mortality risk in patients with NAFLD. Methods This study analyzed data from 13,450 patients with NAFLD in the National Health and Nutrition Examination Survey (NHANES) database, covering the years 1999 to 2018. Patients were categorized into three groups based on their blood Cd levels. The relationship between blood cadmium concentrations and all-cause, cardiovascular, and cancer mortality in NAFLD patients was assessed using Cox proportional hazards regression while accounting for potential confounders. Results were visualized using Kaplan–Meier and restricted cubic spline (RCS) curves. Stratified analyses were performed for validation of the robustness of the results. Results After adjusting for all covariates, blood Cd levels were positively associated with all-cause, cardiovascular, and cancer mortality in patients with NAFLD, showing a significant linear dose–response relationship. Specifically, for each unit increase in Log-transformed blood cadmium concentration, the risk of all-cause mortality increased by 191% (HR = 2.91, 95% CI: 2.39–3.53); cardiovascular mortality risk increased by 160% (HR = 2.6, 95% CI: 1.80–3.76); and cancer mortality risk increased by 279% (HR = 3.79, 95% CI: 2.54–5.65). Stratified analysis confirmed the robustness of these findings. Conclusion Our study suggests that high Blood Cd levels adversely affect the prognosis of patients with NAFLD. Individuals with NAFLD should be aware of Cd exposure and take preventive measures. Moreover, stricter environmental protection policies may be necessary to reduce Cd exposure.