C-reactive protein/serum chloride ratio: a novel marker of all-cause mortality in prevalent chronic haemodialysis patients

Abstract

Background and Aims Serum chloride (Cl-) is an emerging marker of mortality in hypertension, sepsis, heart failure and chronic kidney disease. The pathophysiological mechanism is unclear, but haemodynamic and inflammatory factors have been suggested. As C-reactive protein (CRP) is an established marker of inflammation and prognosis in haemodialysis patients, we sought to determine whether there is an association between the CRP/Cl- ratio and prognosis in these patients.

Method Retrospective cohort study. We included n = 281 prevalent patients in our chronic haemodialysis programme between 19 January 2022 and 11 August 2022. The mean follow-up was 10 months. The sample was divided into quartiles according to CPR/Cl— ratio values. Baseline demographic, analytical and bioimpedance data were collected (Table 1). Survival time was recorded in all patients and analysed using the Kaplan-Meier method.

Results The median CPR/Cl— ratio was 0.04 mg/mEq (0.02; 0.12). Women accounted for 31.8%. 28.9% had underlying diabetic nephropathy. Overall survival at 10 months was 87.9%. Patients who died had a higher CPR/Cl— value [0.12 (0.04; 0.19)] vs [0.04 (0.02; 0.10)] (p = 0.0005). In addition, those in the fourth quartile had a lower probability of survival compared to the other quartiles (p = 0.0011, log-rank test) (Fig. 1).

Conclusion Higher values of the CPR/Cl index were associated with higher all-cause mortality in our sample of prevalent haemodialysis patients.