The Association Between Serum β₂-microglobulin Levels And Prognosis In Maintenance Hemodialysis Patients: A Prospective Cohort Study

Background:The association between serum β₂-microglobulin（ β₂M）levels and the risk of all-cause and cardiovascular disease（CVD）mortality in patients undergoing maintenance hemodialysis（MHD）is inconclusive.Furthermore,few studies have been performed in China on the significance of serum β₂M levels in MHD patients.Therefore,this study investigated the aforementioned association in MHD patients.Methods:In this prospective cohort study,MHD patients were followed at Dalian Municipal Central Hospital from December 2019 to December 2021.The serum β₂M levels were categorized into three tertiles,and the lowest tertile served as the reference group.One-way ANOVA test,Kruskal–Wallis H test or chi-square test were used to analyze the differences in baseline characteristics among the three groups.Spearman or point biserial correlation analysis method was used to analyze the correlation between baseline characteristics and serum β₂M levels.Multiple linear regression analysis was used to explore the fact affecting of serum β₂M levels.Survival curves were calculated by the Kaplan–Meier method.Hazard ratios（HRs）and 95%confidence intervals（CIs）were calculated using Cox proportional hazard models.Sensitivity analysis of the associations of serum β₂M levels with the risk of all-cause and CVD mortality was performed by cox proportional hazard models in patients without of CVD at baseline.Results:A total of 521 MHD patients were included,58.1%of whom were men.The median（interquartile spacing,IQR）age of the patients was 60 year（19 years）and the median（IQR）dialysis duration was 54 months（67 months）.During the follow-up period of（21.4±6.3）months,there were 109 deaths,of which 68 had a cardiovascular cause.Patients in the highest β₂M tertile（>45.4 mg/L）tended to be older,have longer dialysis durations and higher serum C-reactive protein（CRP）levels,and require more low-flux dialyzation（P<0.05）than patients in the lowest β₂M tertile（<34.9 mg/L）.In addition,patients in the highest β₂M tertile were more likely to have lower body mass index（BMI）,as well as lower serum hemoglobin（Hb）and creatinine（Cr）levels（P<0.05）.In correlation analysis,age,duration of dialysis,CRP,BUN,BMI and dialyzation mode were significantly correlated with serum β₂M levels（P<0.05）.In multiple linear regression analysis,serum β₂M level is positively correlated with duration of dialysis,serum CRP and BUN levels,and negatively correlated with age,BMI and dialyzation mode（P<0.05）.The Kaplan–Meier survival curves of patients with different serum β₂M levels are shown that a greater number of patients associated with the risk of all-cause and CVD mortality in the highest β₂M tertile compared with the lowest β₂M tertile（log-rank test,P<0.05）.After adjusting for age,gender,duration of dialysis,Hb,albumin（Alb）,Cr,CRP,BMI,primary disease,hypertension,diabetes,and dialyzation mode,serum β₂M levels were positively associated with the risk of all-cause（HR=2.24,95%CI=1.2–4.17）and CVD（HR=2.54,95%CI=1.19–5.43）mortality,and a linear trend was evident（P<0.05）.Besides,when the serum β₂M levels increased by one SD,serum β₂M levels were also associated with the risk of all-cause（HR=1.36,95%CI=1.10-1.67）and CVD（HR=1.45,95%CI=1.15-1.83）mortality.The results of sensitivity analysis were consistent with the main findings.Conclusion:Serum β₂M levels are positively correlated with duration of dialysis,serum CRP and BUN levels,and negatively correlated with age and BMI.The serum β₂M level may be a significant predictor of the risk of all-cause and CVD mortality in MHD patients.High-flux dialyzation can reduce serum β₂M levels in MHD patients,which may be one of the mechanisms of high-flux dialyzation to improve the prognosis of MHD patients.Further prospective large-scale studies are needed to confirm this finding.