Associations Of Multiple Metals Exposure With Hypertension Risk In Older Adults

Introduction:This thesis evaluated the association between combined exposure to metal elements and the risk of hypertension in Chinese community elderly through studying exposure to metallic elements in the population and hypertension in the elderly.Based on the results of this study,the measures to improve and control hypertension in the elderly were discussed,which provided theoretical basis and suggestions for the prevention and treatment of hypertension in the elderly.Methods:This survey recruited 1080 community-dwelling older adults in their 60s from two communities in urban and rural areas of Lu’an City,Anhui Province,in 2016.And all included participants were required to carried out physical examination,blood sample collection and questionnaire survey,respectively.Upper arm blood pressure（BP）was measured with a mercury sphygmomanometer.The whole blood levels of 7 heavy metals（Pb,Mn,Ni,As,Cd,Cr and V）were measured by an inductively Coupled Plasma Mass Spectrometer（ICP-MS）.Hierarchical logistic regression models were applied to evaluate the associations between blood concentrations of heavy metals and hypertension.And we applied Bayesian kernel machine regression（BKMR）（Bobb et al.,2018;Bobb et al.,2015）to model the joint associations of the metal mixture with prevalence of hypertension and the possible interaction between heavy metals.Results:Finally,among the 1,009 older adults included in our study,459（45.49%）of who were male,550（54.51%）female,530（56.86%）were aged from 60 to 70,459（43.14%）over 71;515（51.04%）had high blood pressure.The detection rates of heavy metals（Pb,Mn,Ni,As,Cd,Cr and V）were over 82%.Unadjusted single-metal models showed a significantly positive association between Mn and hypertension prevalence（OR=1.145,95%CI:1.004,1.305）,significantly negative associations between Ni,Cd,Cr,V and hypertension prevalence（OR=0.799,95%CI:0.678,0.942;OR=0.837,95%CI:0.732,0.957;OR=0.796,95%CI:0.675,0.937;OR=1.145,95%CI:1.004,1.305;OR=0.796,95%CI:0.638,0.928）.Adjusted single-metal models only showed a significantly positive association between Pb and hypertension prevalence（OR=1.241,95%CI:1.031,1.495）.Multi-metal models showed Pb（OR=1.215,95%CI=1.005,1.467）was positively associated with the risk of hypertension,V（OR=0.825,95%CI:0.683,0.997）was negatively associated with the risk of hypertension in older adults.In the same way,we divided whole blood concentrations of individual metals into quartiles（Q1,Q2,Q3,and Q4）and used Q1 as the reference to relax the assumption of linear relationships between blood concentrations of heavy metals and hypertension.Compared with Q1 of Pb,the Q3 and Q4 had elevated odds of hypertension in adjusted single-metal models(OR_{Q4 vs.Q1}=1.663,95%CI=1.087,1.134)and in multi-metal models(OR_{Q4 vs.Q1}=1.655,95%CI=1.058,1.334).According to the analysis results of BKMR models,it displayed that a significantly positive joint effect of mixture of Pb,Mn,Ni,As,Cd,Cr and V on the risk of hypertension.Pb was the most key contributor to metal mixtures（PIP=0.9192）.It is found that Pb was positively associated with the risk of hypertension,while V was negatively associated with the risk of hypertension.Furthermore,our results demonstrated dose-response relationships between Pb,Mn,Ni and the risk of hypertension.In other words,the level of hypertension changes with concentrations of these three metals.Conclusion:It is found that Mn and Pb were positively associated with the risk of hypertension,V was negatively associated with the risk of hypertension.Higher concentrations of metal elements in the blood would increase the risk of hypertension in the elderly where Pb plays most key role,suggesting that we should be alert to exposure of the population to Pb in life.The study on the relationship between metal mixtures and hypertension risk in the elderly has improved the previous study,which only considers the deficiency of exposure to single metal elements,making the research results more practical.However,since this study is a cross-sectional study,it still needs to be further improved and verified.