Associations Of Multiple Metals/Metaloids With Kidney Function In Elderly Hypertensive Population

Background A growing number of epidemiological studies have been devoted to exploring the association between some metals/metalloids and kidney function in the general population,but fewer studies have examined this association in the elderly hypertensive population and few have explored the role of blood pressure control in it.ObjectiveThe purpose of this study was to investigate the association between multiple metals/metalloids and kidney function in the elderly hypertensive population and the role of blood pressure control in it,and to provide theoretical basis and suggestions for improving kidney function in the elderly population based on the results of the study.MethodsA total of 513 older adults were included in this study using stratified whole-group sampling,and all eligible groups of older adults were grouped according to their existing hypertension prevalence status(i.e.,those with hypertension and controlled blood pressure(N=149),and those with hypertension but uncontrolled blood pressure(N=364)).The inductively coupled plasma mass spectrometer(ICP-MS)was used for the determination of eight metals/metalloids [vanadium(V),chromium(Cr),strontium(Sr),manganese(Mn),nickel(Ni),cadmium(Cd),arsenic(As),and lead(Pb)] in whole blood.The estimated Glomerular Filtration Rate(eGFR)was calculated based on serum creatinine to assess kidney function.Linear regression and Bayesian kernel machine regression(BKMR)models were used to explore the relationship between single as well as mixed metals/metalloids and eGFR(continuous type variable outcomes).ResultsThe results of the linear regression model showed a negative linear association between metal/metalloid mixtures(continuous variables)and eGFR in all elderly populations with hypertension after adjusting for all potential confounders,where blood levels of V,Sr,As,and Pb were each significantly and negatively associated with eGFR with beta values(95% CI)of-0.032(-0.063 to-0.002),-0.071(-0.104 to-0.039),-0.060(-0.088 to-0.032)and-0.031(-0.059 to-0.002),respectively;in the uncontrolled group of hypertension,there was also a negative linear association between metal/metalloid mixture and eGFR,where blood levels of Sr,As and Pb,respectively,were associated with eGFR showed a significant negative association with β values(95% CI)of-0.078(-0.119 to-0.038),-0.068(-0.103 to-0.034)and-0.038(-0.073 to-0.002),respectively;however,in the hypertension control group,the linear association between metals and metalloids disappeared,and only blood V showed a significant negative association with eGFR and a β value(95% CI)of-0.081(-0.150 to-0.012),and blood Cr showed a significant positive association with eGFR and a β value(95% CI)of 0.069(0.007 to 0.132).The results obtained for the metal quartile levels in the linear regression model are similar to those obtained for them as continuous variables.The results of the BKMR model analysis showed that in the total hypertensive population and in the hypertensive uncontrolled group,higher levels of metal/metalloid mixes in blood were significantly associated with lower eGFR levels were significantly associated with a dose-response relationship.Sr and As in the metal/metalloid mixture were the largest contributors to the decrease in eGFR in older adults in the total hypertensive population and in the uncontrolled hypertensive group,with a posterior inclusion probability(PIP)of 0.9940 and 0.5877,respectively.in addition,there were significant interactions.However,when blood pressure was controlled,the linear relationship between metals and renal function disappeared and the large interactions between metals were absent.ConclusionOur study shows that Sr,As and Pb in blood are negatively associated with kidney function in older adults with hypertension,either alone or as a mixture.Metal mixtures showed a linear dose-response relationship with impaired kidney function,with Sr and Pb being the most important components of the mixtures.Furthermore,we found that the linear relationship between metals and kidney function disappeared after blood pressure control.This study is the first to explore the potential impact of blood pressure control or not on the association between metals and kidney function.Further cohort studies are still needed in the future to elucidate the association between metal mixtures and kidney function in elderly population with hypertension,and to explore in depth the potential mechanisms of blood pressure control to provide a theoretical and policy basis for the prevention and control of kidney injury in the elderly population.