Association between serum chloride levels with mortality in incident peritoneal dialysis patients

Background and aims Lower serum chloride (Cl) levels have been associated with excess mortality in pre-dialysis chronic kidney disease patients. However, the relationship between serum Cl levels and clinical outcomes in continuous ambulatory peritoneal dialysis (CAPD) patients is unclear. Methods and results In this retrospective cohort study, we enrolled 1656 eligible incident patients undergoing CAPD from 2006 to 2013, and followed until December 2018. Cox regression analyses were used to examine the association between baseline and time-varying serum Cl levels and mortality. During a median follow-up of 46 months, 503 patients (30.4%) died. In analyses of baseline serum Cl, the adjusted hazard ratios (HR) for tertile 1 (<100.0 mmol/L), tertile 2 (100.0–103.0 mmol/L) versus tertile 3 (>103.0 mmol/L) were 2.34 [95% confidence interval (CI) 1.43–3.82] and 1.73 (95% CI 1.24–2.42) for all-cause mortality, 2.86 (95% CI 1.47–5.56) and 1.90 (95% CI 1.19–3.02) for cardiovascular disease (CVD) mortality, respectively. And a linear relationship was observed between serum Cl and mortality. Further, the inverse association between serum Cl and CVD mortality was particularly accentuated in the patients who were ≥50 years or with a history of diabetes. Similarly, lower time-varying serum Cl levels were also associated with a significant increased risk of all-cause and CVD death. Conclusion Lower serum Cl levels predicted higher risk of all-cause and CVD mortality in CAPD patients.