Serum Chloride and Mortality in Patients on Continuous Ambulatory Peritoneal Dialysis: A Multicenter Retrospective Study

Background: Lower serum chloride is associated with a higher risk of mortality in the general population. However, the association has received little attention in peritoneal dialysis patients. The study aimed to examine the association between serum chloride and mortality in peritoneal dialysis patients. Methods: In this multicenter retrospective cohort study, 2376 Chinese incident patients on peritoneal dialysis between January 1, 2005, and March 31, 2020, were enrolled. Patients were grouped according to quartiles of serum chloride at baseline. The associations of baseline serum chloride and cardiovascular mortality and all-cause mortality were evaluated using cause-specific hazards models. Findings: Of 2376 patients, the median age was 48.0 (38.0,58.0) years, 50.1% of patients were men. The median serum chloride levels were 103.0 (99.0,106.9) mmol/L. During 9304.5 person-years of follow-up, 462 patients died, of which 235 deaths were caused by cardiovascular disease. The highest quartile group was associated with a higher risk of cardiovascular mortality (adjusted hazards ratio [HR], 3.12; 95% confidence interval [CI], 1.86 to 5.23) and all-cause mortality (adjusted HR, 2.17; 95% CI, 1.53 to 3.07) compared with the lowest quartile (P for trend <0.001). The similar trend was also found when serum chloride levels were deal as continuous variable. Interpretation: Higher serum chloride at the initial of peritoneal dialysis was associated with a higher risk of cardiovascular mortality and all-cause mortality in patients on peritoneal dialysis. Funding: This work was supported by Shanghai Municipal Health Commission (2019SY018). Declaration of Interest: None to declare. Ethical Approval: The study protocol complied with the Declaration of Helsinki and had full approval from each Clinical Research Ethics Committee