Hyponatremia Predicts New-Onset Cardiovascular Events in Peritoneal Dialysis Patients

Abstract

Background and AimCardiovascular (CV) disease is the leading cause of morbidity and mortality in patients on peritoneal dialysis (PD). Hyponatremia was recently shown to be a modifiable factor that is strongly associated with increased mortality in PD patients. However, the clinical impact of hyponatremia on CV outcomes in these patients is unclear.MethodsTo determine whether a low serum sodium level predicts the development of CV disease, we carried out a prospective observational study of 441 incident patients who started PD between January 2000 and December 2005. Time-averaged serum sodium (TA-Na) levels were determined to investigate the ability of hyponatremia to predict newly developed CV events in these patients.ResultsDuring a mean follow-up of 43.2 months, 106 (24.0%) patients developed new CV events. The cumulative incidence of new-onset CV events after the initiation of PD was significantly higher in patients with TA-Na levels ≤ 138 mEq/L than in those with a TA-Na > 138 mEq/L. After adjustment for multiple potentially confounding covariates, an increase in TA-Na level was found to be associated with a significantly lower risk of CV events (subdistribution hazard ratio per 1 mEq/L increase, 0.90; 95% confidence interval, 0.83–0.96; p = 0.003). Patients with a TA-Na ≤ 138 mEq/L had a 2.31-fold higher risk of suffering a CV event.ConclusionsThese results provide evidence of a clear association between low serum sodium and new-onset CV events after dialysis initiation in PD patients. Whether the correction of hyponatremia for this indication provides additional protection for the development of CV disease in these patients remains to be addressed in interventional studies.

The Effect of Serum Sodium on Survival in Patients Treated by Peritoneal Dialysis in the United Kingdom

“…This association between mortality and hyponatraemia was modified by age, with our younger age group having more than a twofold increased risk of death, even after adjusting for age and other covariates associated with mortality. Whereas some studies have reported an increased mortality with increasing serum sodium [10], we found a relative protective effect of higher serum sodium concentrations, in keeping with the DOPPS report in haemodialysis patients [6] and one smaller study in peritoneal dialysis patients [11].…”

Association of serum sodium levels with all‐cause and cardiovascular mortality in chronic kidney disease: Results from a prospective observational study

“…The results support other literature that hyponatraemia is a powerful adverse prognostic marker . However, there are still many unanswered questions.…”

“…Similarly, it is well reported that hyponatraemia and hypernatraemia are associated with mortality in hospitalized patients and certain subgroups such as patients with cardiac failure . For patients with renal disease, hyponatraemia was reported as a risk factor for mortality and new onset cardiovascular events in patients undergoing peritoneal dialysis. Certainly, in experimental studies, it has been shown that hyponatraemia has a direct effect on suppression of cardiac myocyte function .…”

Practical recommendations for reportingFine‐Gray model analyses for competing risk data

“…The authors interpreted this as right‐sided radiation therapy increasing the cumulative incidence 1.19‐fold (p 1066), which is only approximately correct. Similarly, in a study examining the effect of hyponatremia on the incidence of cardiovascular events in peritoneal dialysis patients, the authors estimated a subdistribution hazard ratio of 2.31 . The authors interpreted this as meaning that patients with hyponatremia had a 2.31‐fold higher risk of cardiovascular events (p 4/10).…”