Objective To investigate the predictive value of early serum potassium (sK) level combined with the hypersensitive C-reactive protein to albumin ratio (CAR) for all-cause mortality in patients undergoing continuous ambulatory peritoneal dialysis (CAPD). Methods A single-center retrospective cohort study was conducted. Data were collected from CAPD patients who underwent catheterization at the Peritoneal Dialysis Center of Xuzhou Municipal Hospital Affiliated to Xuzhou Medical University from January 2016 to January 2024. Early sK was defined as the mean value of sK within the first three months after initiating peritoneal dialysis. Patients were divided into three groups according to sK level: hypokalemia group (sK＜3.5 mmol/L), normokalemia group (3.5≤sK≤5.5 mmol/L), and hyperkalemia group (sK>5.5 mmol/L). General characteristics and laboratory indicators were compared among the groups. Multivariate Cox proportional hazards regression model was used to analyze factors associated with all-cause mortality. Restricted cubic spline (RCS) analysis was applied to examine the relationship between early sK, CAR and all-cause mortality. Receiver operating characteristic (ROC) curves were used to evaluate the predictive value of early sK combined with CAR for all-cause mortality. Results A total of 462 CAPD patients were enrolled, including 93(20.1%) in the hypokalemia group, 345(74.7%) in the normokalemia group, and 24(5.2%) in the hyperkalemia group. The median follow-up time was 40.0(22.0,63.0) months, and 96 patients (20.8%) died. Multivariate Cox regression analysis showed that age (HR=1.059, 95% CI: 1.037～1.082, P＜0.001), hemoglobin (HR=0.987, 95% CI: 0.974～1.000, P=0.046), sK(HR=0.718, 95% CI: 0.523～0.985, P=0.040), and CAR (HR=2.867, 95% CI: 1.742～4.720, P＜0.001) were independent factors influencing all-cause mortality in CAPD patients. RCS analysis revealed a U-shaped association between early sK level and the risk of all-cause mortality, with the lowest risk at a sK level of 4.397 mmol/L. The association between CAR and all-cause mortality was L-shaped, with an optimal cut-off value of 0.323 mg/g. Combined analysis of sK and CAR showed significantly increased mortality risk in the hypokalemia + high CAR group (HR=2.361, 95% CI:1.214～4.591, P=0.011), hypokalemia+low CAR group (HR=1.808, 95%CI:1.059～3.085,P=0.030), and hyperkalemia + high CAR group (HR=3.191, 95% CI: 1.149～8.465, P=0.026). The area under the ROC curve (AUC) for sK combined with CAR (AUC=0.737, 95% CI:0.678～0.797, P＜0.001) was superior to that of sK alone (AUC=0.694, 95% CI:0.626～0.761,P＜0.001) or CAR alone (AUC=0.709, 95% CI:0.654～0.765, P＜0.001) in predicting all‑cause mortality. Conclusion Early sK level and CAR are influencing factors for all-cause mortality in CAPD patients. The combination of sK and CAR further improves the predictive value for mortality risk.
Key words
Continuous ambulatory peritoneal dialysis /
Serum potassium /
Hypersensitive C-reactive protein to albumin ratio /
All-cause mortality
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