Potassium supplementation and long-term outcomes in chronic peritoneal dialysis patients with end-stage renal disease: a propensity score matching study

Abstract

Objective: In this retrospective matched-cohort study, the association between potassium supplementation and long-term outcomes was determined.

Methods: Chronic peritoneal dialysis (PD) patients, aged ≥ 16 years, being referred to four PD centers in China, with serum potassium levels ≤ 3.5 mEq/L on three consecutive monthly in Q4 2008 and without receiving oral potassium supplementation in the prior three months were included in this study. Patients were divided into two groups, either to receive (test group) or not (control group) oral potassium supplementation in both Q4 2008 and the subsequent follow-up period, until 31 December 2014. The patients from the test group were matched to those from the control group using a propensity score. The clinical outcomes for all-cause and cardiovascular mortality were estimated by Matched Cox regression models during 61.5 months of median follow-up. All patients were also categorized according to serum potassium correction levels (<3.0, 3.0 to <4.0, 4.0 to <5.0 and ≥5.0 mEq/L) after the whole follow-up. The hazard ratios (HRs) were used to assess the relationship between corrected potassium levels and all-cause and cardiovascular mortality in PD patients. Subgroup analysis was used to determine the homogeneity of the associations between potassium supplementation and all-cause mortality.

Results: All-cause mortality occurred in 108 patients (605/10,000 person-years) in the test group and 114 patients (677/10,000 person-years) in the control group during 1786- and 1685-year follow-up, respectively [hazard ratio (HR), 0.89; 95% confidence interval (CI), 0.68-1.16; p = 0.38]. Cardiovascular mortality occurred in 97 patients (542/10,000 person-years) in the test group and 101 patients (598/10,000 person-years) in the control group (HR, 0.89; 95% CI, 0.67-1.18; p = 0.43). There were no significant interactions between potassium supplementation and any of the subgroups, except for diabetes mellitus and volume overload. During a median follow-up of 61.5 months, adjusted all-cause mortality hazard ratio (HR) and 95% confidence interval (CI) for corrected serum potassium of <3.0, 3.0 to < 4.0, and ≥5.0 mEq/L, compared with 4.0 to < 5.0 mEq/L (reference), were 2.23 (1.17-3.72), 1.35 (0.89-1.81), and 1.74 (1.05-3.72), respectively.

Conclusion: The use of potassium supplementation in chronic PD patients is not associated with mortality. While it may be necessary for the correction of hypokalemia or the maintenance of normokalemia, and the consequent reduction of hypokalemia-associated mortality. Additionally, use of aldosterone antagonists may be preferable for the handling of hypokalemia in PD patients.

Keywords: Peritoneal dialysis; mortality; outcome; potassium supplementation; propensity score.