Association between cadmium exposure and risk of chronic kidney disease; a systematic review and meta-analysis

Introduction: Chronic kidney disease (CKD) is the twelfth most common cause of death worldwide. The kidneys are the primary site of cadmium accumulation and the most sensitive organ to cadmium toxicity. Therefore, the current study aimed to investigate the relationship between cadmium exposure and the risk of CKD using a systematic review and meta-analysis method. Materials and Methods: In this systematic review and meta-analysis, databases including PubMed, Scopus, Web of Science, Cochrane, and Google Scholar were searched without time restrictions until September 9, 2023. Data were analyzed using STATA 14 software, and P <0.05 was considered statistically significant. Results: The results of combining 18 observational studies with a total of 230,790 participants showed that an increase in blood cadmium levels was associated with an increased risk of CKD (OR: 1.42; 95% CI: 1.18, 1.70). This association was significant in cross-sectional studies (OR: 1.21; 95% CI: 1.04, 1.41), case-control studies (OR: 3.08; 95% CI: 1.47, 6.41), and cohort studies (OR: 1.36; 95% CI: 0.85, 2.17). Generally, the relationship between urinary cadmium levels and CKD was not statistically significant (OR: 1.14; 95% CI: 0.84, 1.54). In cross-sectional studies, high urinary cadmium levels reduced the risk of CKD (OR: 0.77; 95% CI: 0.60, 0.99). However, in case-control studies, the relationship between high urinary cadmium levels and risk of CKD was not statistically significant (OR: 0.20; 95% CI: 0.02, 2.40). Since in cohort studies, high urinary cadmium levels were a risk factor for CKD (OR: 1.40; 95% CI: 1.07, 1.83)]. The relationship between cadmium consumption and the risk of CKD was statistically significant (OR: 1.55; 95% CI: 1.00, 2.42), with significance in case-control studies (OR: 18.16; 95% CI: 1.75, 188.64) but not in cohort studies (OR: 1.45; 95% CI: 0.93, 2.25). Conclusion: Overall, an increase in blood cadmium levels was associated with a 42% increased risk of CKD. Furthermore, cadmium consumption through the diet increased the risk of CKD by 55%. Registration: This study has been compiled based on the PRISMA checklist, and its protocol was registered on the PROSPERO (ID: CRD42023463145).