Serum β₂-Microglobulin Predicts Mortality in Peritoneal Dialysis Patients: A Prospective Cohort Study

Background/Aims: β₂-Microglobulin (β₂-M) is a surrogate marker of middle-molecule uremic toxins and is associated with mortality in chronic hemodialysis patients. However, the impact of serum β₂-M levels on mortality in peritoneal dialysis (PD) patients is uncertain. The purpose of this study was to examine the association of serum β₂-M levels with all-cause mortality in PD patients. Methods: A total of 771 PD patients were selected from the Clinical Research Center registry for end-stage renal disease cohort in Korea. Patients were categorized into 3 groups by tertiles of serum β₂-M levels. The primary outcome was all-cause mortality. Results: The median value of serum β₂-M was 23.6 mg/l (interquartile range 14.8-33.4 mg/l), and the median follow-up period was 39 months. The Kaplan-Meier analysis showed that the all-cause mortality rate was significantly different according to tertiles of serum β₂-M in PD patients (p = 0.03, log-rank). Multivariate Cox proportional analysis showed that the hazards ratio for all-cause mortality was 1.02 (95% CI 1.01-1.04, p = 0.006) per 1 mg/l increase in β₂-M after adjustment for multiple confounding factors that relate to malnutrition and inflammation marker. However, serum β₂-M was not associated with all-cause mortality after adjustment for residual renal clearance. Conclusions: These results are supportive of the potential role of the serum β₂-M level as a predictor of mortality in PD patients.