Dialysate Potassium, Serum Potassium, Mortality, and Arrhythmia Events in Hemodialysis: Results From the Dialysis Outcomes and Practice Patterns Study (DOPPS)

Abstract

Background: Sudden death is a leading cause of death in patients on maintenance hemodialysis therapy. During hemodialysis sessions, the gradient between serum and dialysate levels results in rapid electrolyte shifts, which may contribute to arrhythmias and sudden death. Controversies exist about the optimal electrolyte concentration in the dialysate; specifically, it is unclear whether patient outcomes differ among those treated with a dialysate potassium concentration of 3 mEq/L compared to 2 mEq/L.

Study design: Prospective cohort study.

Setting & participants: 55,183 patients from 20 countries in the Dialysis Outcomes and Practice Patterns Study (DOPPS) phases 1 to 5 (1996-2015).

Predictor: Dialysate potassium concentration at study entry.

Outcomes: Cox regression was used to estimate the association between dialysate potassium concentration and both all-cause mortality and an arrhythmia composite outcome (arrhythmia-related hospitalization or sudden death), adjusting for potential confounders.

Results: During a median follow-up of 16.5 months, 24% of patients died and 7% had an arrhythmia composite outcome. No meaningful difference in clinical outcomes was observed for patients treated with a dialysate potassium concentration of 3 versus 2 mEq/L (adjusted HRs were 0.96 [95% CI, 0.91-1.01] for mortality and 0.98 [95% CI, 0.88-1.08] for arrhythmia composite). Results were similar across predialysis serum potassium levels. As in prior studies, higher serum potassium level was associated with adverse outcomes. However, dialysate potassium concentration had only minimal impact on serum potassium level measured predialysis (+0.09 [95% CI, 0.05-0.14] mEq/L serum potassium per 1 mEq/L greater dialysate potassium concentration).

Limitations: Data were not available for delivered (vs prescribed) dialysate potassium concentration and postdialysis serum potassium level; possible unmeasured confounding.

Conclusions: In combination, these results suggest that approaches other than altering dialysate potassium concentration (eg, education on dietary potassium sources and prescription of potassium-binding medications) may merit further attention to reduce risks associated with high serum potassium levels.

Keywords: Dialysate potassium; Dialysis Outcomes and Practice Patterns Study (DOPPS); arrhythmia; cardiac instability; electrolyte shift; end-stage renal disease (ESRD); hemodialysis; hyperkalemia; mortality; potassium gradient; serum potassium; sudden death.

Figure 1. Flow chart of DOPPS patients eligible for analysis

*Current as of September 29, 2015. SK=serum potassium; DK=dialysate potassium.

Figure 2a. Pre-dialysis serum K distribution by country in DOPPS phase 5 (2012–2015)

N=17,815 patients. Country abbreviations: A/NZ=Australia and New Zealand, Bel=Belgium, Can=Canada, Chi=China, Fra=France, GCC=Gulf Cooperation Council (Bahrain, Kuwait, Oman, Qatar, Saudi Arabia, United Arab Emirates), Ger=Germany, Ita=Italy, Jpn=Japan, Rus=Russia, Spa=Spain, Swe=Sweden, Tur=Turkey, UK=United Kingdom, US=United States.

Figure 2b. Temporal trends in pre-dialysis serum K by DOPPS region (1996–2015)

N=67,263 patients. DOPPS phase 1: 1996–2001, phase 2: 2002–2004, phase 3: 2005–2008, phase 4: 2009–2011, phase 5: 2012–2015. A/NZ=Australia and New Zealand. Note that countries recently joining the DOPPS in phase 5 (N=3,334 patients) are not represented in this figure.

Figure 3a. Dialysate K distribution by country in DOPPS phase 5 (2012–2015)

*Indicates proportion of facilities prescribing a uniform dialysate K to ≥90% of patients. N=17,815 patients. Country abbreviations: A/NZ=Australia and New Zealand, Bel=Belgium, Can=Canada, Chi=China, Fra=France, GCC=Gulf Cooperation Council (Bahrain, Kuwait, Oman, Qatar, Saudi Arabia, United Arab Emirates), Ger=Germany, Ita=Italy, Jpn=Japan, Rus=Russia, Spa=Spain, Swe=Sweden, Tur=Turkey, UK=United Kingdom, US=United States. In the DK 3.0–4.0 group, 89% of patients had DK=3.0 mEq/L; in the DK 2.0–2.5 group, 98% of patients had DK=2.0 mEq/L; the DK 1.0–1.5 group was primarily concentrated in Spain, where 98% of patients prescribed DK 1.0–1.5 had DK=1.5 mEq/L; elsewhere, 75% of patients in the 1.0–1.5 group had DK 1.0 mEq/L.

Figure 3b. Temporal trends in dialysate K by DOPPS region (1996–2015)

N=67,263 patients. DOPPS phase 1: 1996–2001, phase 2: 2002–2004, phase 3: 2005–2008, phase 4: 2009–2011, phase 5: 2012–2015. A/NZ=Australia and New Zealand. Note that countries recently joining the DOPPS in phase 5 (N=3,334 patients) are not represented in this figure.