Occupational Lead Exposure and Severe CKD: A Population-Based Case-Control and Prospective Observational Cohort Study in Sweden

Background The role of low-level lead exposure in the cause of chronic kidney disease (CKD) is unsettled. Study Design Case-control study and prospective observational cohort study. Setting & Participants 926 cases with incident severe CKD (serum creatinine > 3.4 mg/dL for men and > 2.8 mg/dL for women for the first time) and 998 population controls were included. Cases represented nearly all patients with incident severe CKD in Sweden during 2 years. Cases also were followed up prospectively for 7-9 years. Exposed and nonexposed cases were compared with regard to rate of change in estimated glomerular filtration rate (eGFR) and renal survival. Predictor Lead exposure was assessed using the expert rating method. Outcomes & Measurements Associations between lead exposure and risk of CKD, adjusted for factors associated with this outcome, were analyzed using multivariable logistic regression modeling, whereas links to the rate of change in eGFR were analyzed in mixed-effects multivariable models based on up to 6 measurements. Renal survival in relation to lead exposure was analyzed in a Cox proportional hazards model. Results The adjusted OR for incident severe CKD was 0.97 (95% CI, 0.68-1.38) in lead-exposed compared with nonexposed participants. The OR for individuals with the highest average exposure (>0.0075 mg/m3 ) was 1.09 (95% CI, 0.64-1.85). ORs for CKD caused by glomerulonephritis, nephrosclerosis, and diabetic nephropathy did not differ importantly. In patients with CKD ever exposed and most exposed to lead, eGFRs changed by −4.27 and −3.39 mL/min/1.73 m2 /y compared with −4.55 mL/min/1.73 m2 /y in nonexposed patients, respectively. Limitations Only native Swedes were included, which may limit generalizability. Blood lead was not measured to confirm the validity of the expert rating method. Conclusion Our data provide no evidence of an important role of low-level occupational lead exposure in the cause or progression of severe CKD.