Serum chloride as a marker of cardiovascular and all-cause mortality in chronic hemodialysis patients: 5-Year follow-up study.

Background: Hypochloremia has been associated with increased mortality in patients with hypertension, heart failure, sepsis, and chronic kidney disease (CKD). The pathophysiological mechanisms of this finding are not clear. There are no studies describing an association between serum chloride levels (Cl) and mortality in incident chronic hemodialysis (HD) patients.

Method: Retrospective cohort study of the incident population in our chronic outpatient hemodialysis program between January 1, 2016, and January 1, 2021 (N=374). Survival time was collected in all patients and analyzed using the Kaplan-Meyer method. A multivariate Cox regression model was performed to predict the probability of survival, applying a stepwise procedure.

Results: During the median follow-up period of 20 months, 83 patients died. The 5-year overall survival rate for our patients was 45%. Both natremia and chloremia had no significant differences when compared by sex, vascular access, or etiology. There was an inverse correlation between Cl and interdialytic weight gain (r=-0.15) (p=0.0038). Patients belonging to the quartile with lower Cl levels had less probability of survival than patients in the quartile with higher Cl levels (27% and 68%, respectively, p=0.019). On the other hand, in the multivariate Cox regression model, variables significantly associated with higher mortality were being older, having higher baseline comorbidity by modified Charlson index, not taking diuretics and having lower albumin and chloride levels. Particularly, higher Cl levels was independently associated with both lower all-cause mortality (adjusted hazard ratio [HR]=0.84; 95% confidence interval [CI], 0.77-0.92; p=0.0001) and cardiovascular mortality (HR 0.9; 95% CI, 0.83-0.97; p<0.0057).

Conclusions: Lower Cl levels were associated with higher all-cause and cardiovascular mortality in incident patients on chronic hemodialysis in our health area.