Dietary Potassium Intake and All-Cause Mortality in Adults Treated with Hemodialysis

Abstract

Background and objectives: Dietary potassium restriction in people receiving maintenance hemodialysis is standard practice and is recommended in guidelines, despite a lack of evidence. We aimed to assess the association between dietary potassium intake and mortality and whether hyperkalemia mediates this association.

Design, setting, participants, & measurements: A total of 8043 adults undergoing maintenance hemodialysis in Europe and South America were included in the DIETary intake, death and hospitalization in adults with end-stage kidney disease treated with HemoDialysis (DIET-HD) study. We measured baseline potassium intake from the Global Allergy and Asthma European Network food frequency questionnaire and performed time-to-event and mediation analyses.

Results: The median potassium intake at baseline was 3.5 (interquartile range, 2.5-5.0) g/d. During a median follow-up of 4.0 years (25,890 person-years), we observed 2921 (36%) deaths. After adjusting for baseline characteristics, including cardiac disease and food groups, dietary potassium intake was not associated with all-cause mortality (per 1 g/d higher dietary potassium intake: hazard ratio, 1.00; 95% confidence interval [95% CI], 0.95 to 1.05). A mediation analysis showed no association of potassium intake with mortality, either through or independent of serum potassium (hazard ratio, 1.00; 95% CI, 1.00 to 1.00 and hazard ratio, 1.01; 95% CI, 0.96 to 1.06, respectively). Potassium intake was not significantly associated with serum levels (0.03; 95% CI, -0.01 to 0.07 mEq/L per 1 g/d higher dietary potassium intake) or the prevalence of hyperkalemia (≥6.0 mEq/L) at baseline (odds ratio, 1.11; 95% CI, 0.89 to 1.37 per 1 g/d higher dietary potassium intake). Hyperkalemia was associated with cardiovascular death (hazard ratio, 1.23; 95% CI, 1.03 to 1.48).

Conclusions: Higher dietary intake of potassium is not associated with hyperkalemia or death in patients treated with hemodialysis.

Keywords: cohort studies; diet; dietary; hemodialysis; mortality; nutrition; potassium.

Graphical abstract

Figure 1.

Simplified directed acyclic graph of the potential causal relationship between dietary potassium intake and mortality. The direct effect is represented by the arrow (c) and the indirect effect by the arrows (a) and (b). The measured potential confounders are included in the set of covariables C.

Figure 2.

Flow chart of the study participants. FFQ, food frequency questionnaire; HD, hemodialysis; K, potassium.

Figure 3.

Association of dietary potassium intake (grams per day) with (A) all-cause mortality, (B) cardiovascular mortality, and (C) noncardiovascular mortality. Models adjusted for the age, sex, smoking status, body mass index, physical activity, presence of a life partner, Charlson comorbidity index, history of cardiac disease, history of diabetes, history of cancer, listed for transplant, type of vascular access, body weight decrease during HD session, number of minutes of HD per week, HD vintage, Kt/V, receiving angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers, serum albumin, total energy intake, and daily intake of each food group. AF, acceleration factor; CV, cardiovascular; CVD, cardiovascular disease.