Effect of blood cadmium level on mortality in patients undergoing maintenance hemodialysis

Previous studies of general populations indicated environmental level cadmium increases mortality. However, the effect of cadmium exposure on maintenance hemodialysis (MHD) patients is unclear. A total of 937 MHD patients from 3 centers in Taiwan were enrolled in this 36-month observational study. Patients were stratified by baseline blood cadmium level (BCL) into 3 groups: high BCL (>0.521mg/L; n=312), intermediate BCL (0.2860.521mg/L; n=313), and low BCL (<0.286mg/L; n=312). The mortality rates and causes of death were analyzed. The analytic results demonstrated patients in the high BCL group had a significantly higher prevalence of malnutrition and inflammation than patients in the low and intermediate BCL groups. After 3 years of follow-up, 164 (17.5%) patients died and the major cause of death was cardiovascular disease. A Cox multivariate analysis indicated the high BCL group had increased hazard ratios (HRs) for all-cause mortality (HR=1.72; 95% confidence interval [CI]: 1.14-2.63; P=0.018), cardiovascular-related mortality (HR=1.85; 95% CI: 1.09-3.23; P=0.032), and infection-related mortality (HR=2.27; 95% CI: 1.12-4.55; P=0.035). A Cox multivariate analysis of MHD patients who never smoked (n=767) indicated the high BCL group had increased HRs for all-cause mortality (HR=1.67; 95% CI: 1.04-2.63; P=0.048) and cardiovascular-related mortality (HR=2.08; 95% CI: 1.08-4.00; P=0.044). In conclusion, BCL is an important determinant of mortality in MHD patients. Therefore, MHD patients should avoid cadmium exposure as much as possible, such as tobacco smoking and eating cadmium-containing foods.