Low Serum Potassium Levels Increase the Infectious-Caused Mortality in Peritoneal Dialysis Patients: A Propensity-Matched Score Study

Abstract

Background and ObjectivesHypokalemia has been consistently associated with high mortality rate in peritoneal dialysis. However, studies investigating if hypokalemia is acting as a surrogate marker of comorbidities or has a direct effect in the risk for mortality have not been studied. Thus, the aim of this study was to analyze the effect of hypokalemia on overall and cause-specific mortality.Design, Setting, Participants and MeasurementsThis is an analysis of BRAZPD II, a nationwide prospective cohort study. All patients on PD for longer than 90 days with measured serum potassium levels were used to verify the association of hypokalemia with overall and cause-specific mortality using a propensity match score to reduce selection bias. In addition, competing risks were also taken into account for the analysis of cause-specific mortality.ResultsThere was a U-shaped relationship between time-averaged serum potassium and all-cause mortality of PD patients. Cardiovascular disease was the main cause of death in the normokalemic group with 133 events (41.8%) followed by PD-non related infections, n=105 (33.0%). Hypokalemia was associated with a 49% increased risk for CV mortality after adjustments for covariates and the presence of competing risks (SHR 1.49; CI95% 1.01-2.21). In contrast, in the group of patients with K <3.5mEq/L, PD-non related infections were the main cause of death with 43 events (44.3%) followed by cardiovascular disease (n=36; 37.1%). For PD-non related infections the SHR was 2.19 (CI95% 1.52-3.14) while for peritonitis was SHR 1.09 (CI95% 0.47-2.49).ConclusionsHypokalemia had a significant impact on overall, cardiovascular and infectious mortality even after adjustments for competing risks. The causative nature of this association suggested by our study raises the need for intervention studies looking at the effect of potassium supplementation on clinical outcomes of PD patients.

Dietary potassium regulates vascular calcification and arterial stiffness

“…concentrations within the normal range (20,21). Reduced potassium is associated with cardiovascular diseases such as hypertension and chronic heart failure, and appropriate dietary potassium intake improves those pathological conditions (22)(23)(24).…”

Impact of hypokalemia on peritonitis in peritoneal dialysis patients: a systematic review

“…The study by Ribeiro et al [12] was well designed for our purposes and performed a propensity score analysis to account for any underlying differences between patients with a timeaveraged potassium under 3.5 mEq/L and others. Although the study with the lowest risk of bias by Su et al [13] excluded cases with acute complication including peritonitis occurred in the previous month, Su et al [13] and Chuang et al [14] had no description about the history of peritonitis.…”

“…Although the study with the lowest risk of bias by Su et al [13] excluded cases with acute complication including peritonitis occurred in the previous month, Su et al [13] and Chuang et al [14] had no description about the history of peritonitis. Peritonitis was not present at the start of the other three studies [12,15,16], which included only incident cases of peritoneal dialysis (Table 2). Ribeiro et al [12] performed a national prospective cohort study with complete follow-up, whereas lost follow-up rate was not described in two retrospective studies [15,16].…”

“…Peritonitis was not present at the start of the other three studies [12,15,16], which included only incident cases of peritoneal dialysis (Table 2). Ribeiro et al [12] performed a national prospective cohort study with complete follow-up, whereas lost follow-up rate was not described in two retrospective studies [15,16]. One case-control study defined controls as responding episodes from partially duplicated subjects with persistent cases [11].…”

“…A Brazilian national cohort study [12] enrolled older subjects and higher prevalence of diabetes than the other singlecenter cohort studies. In this study, hypokalemia based on time-average potassium levels, measured monthly in all patients throughout the whole observational period, had a higher risk for time to first peritonitis episode compared to propensity-matched patients (Fig.…”