RATIONALE & OBJECTIVE: Heavy metals are known to induce kidney damage and recent studies have linked minor exposures to cadmium and arsenic with increased risk of kidney allograft failure, yet the potential association of lead (Pb) with late graft failure in kidney transplant recipients (KTR) remains unknown.
STUDY DESIGN: Prospective cohort study in the Netherlands.
SETTING & PARTICIPANTS: We studied outpatient KTR (n=670) with a functioning graft for ≥1 year recruited at a university setting (2008-2011, NCT02811835) and followed, on average, for 4.9 (IQR, 3.4‒5.5) years. Additionally, end-stage kidney disease patients (n=46) enrolled in the ongoing TransplantLines Cohort and Biobank Study (2016-2017, NCT03272841) were studied at admission for transplantation and at 3, 6, 12, and 24 months after transplantation.
EXPOSURE: Plasma Pb was log2 transformed to estimate the association with outcomes per doubling of plasma Pb concentration and also considered categorically as tertiles of the Pb distribution.
OUTCOME: Kidney graft failure (restart of dialysis or re-transplantation) with the competing event of death with a functioning graft.
ANALYTICAL APPROACH: Multivariable-adjusted cause-specific hazards models where follow-up of KTR who died with a functioning graft was censored.
RESULTS: Median baseline plasma Pb was 0.31 (IQR, 0.22─0.45) μg/L among all KTRs. During follow-up, 78 (12%) KTR developed graft failure. Higher plasma Pb was associated with increased risk of graft failure (HR 1.59, 95% CI 1.14‒2.21 per doubling; P=0.006) independent of age, sex, transplant characteristics, eGFR, proteinuria, smoking status, alcohol intake, and plasma concentrations of cadmium and arsenic. These findings remained materially unchanged after additional adjustment for dietary intake and were consistent with those of analyses examining Pb categorically. In serial measurements, plasma Pb was significantly higher at admission for transplantation than at 3-months post-transplant (P=0.001), after which it remained stable over 2 years of follow-up (P=0.2).
LIMITATIONS: Observational study design.
CONCLUSIONS: Pretransplant plasma Pb concentrations, which fall after transplantation, are associated with increased risk of late kidney allograft failure. These findings warrant further studies to evaluate whether preventive or therapeutic interventions to decrease plasma Pb may represent novel risk-management strategies to decrease the rate of kidney allograft failure.