Dietary potassium and fiber intake, survival, and health-related quality of life, in a prospective multi-center hemodialysis cohort

Abstract

Background & Aims: Among end stage kidney disease (ESKD) patients, guidelines recommend dietary potassium (K) restriction given concerns about hyperkalemia. Yet there are sparse data informing dietary K intake recommendations in this population. We examined associations between dietary K intake and fiber consumption with mortality and health-related quality of life (HRQOL) in a multi-center prospective hemodialysis cohort. Methods: Among 687 hemodialysis patients from the prospective NIH "Malnutrition and Racial Disparities in Chronic Kidney Disease" cohort recruited across 16 dialysis clinics, dietary K intake was assessed using protocolized Food Frequency Questionnaires (FFQs) over 10/2011-9/2022. Given the high fiber content of plant-based K-rich foods, we examined associations of dietary K and fiber pairings across four exposure groups (low K/low fiber, low K/high fiber, high K/low fiber, high K/high fiber) with mortality using Cox regression and Short-Form 36 survey HRQOL scores using linear mixed effects models. To account for energy intake differences, we used a "Standard Model" and "Residual Model" which directly and indirectly adjusted for energy using a residual, respectively. Results: High K/high fiber intake was associated with lower mortality in expanded case-mix analyses in Standard Models (ref: low K/low fiber): aHR (95%CI) 0.69 (0.50, 0.96). High K/high fiber intake was associated with higher (better) HRQOL physical functioning and physical component scores over time using Standard Models (ref: low K/low fiber): estimates (beta) (95 % CIs) +7.54 (1.99, 13.09) and +1.96 (0.07, 3.84), respectively. High K/high fiber intake was also associated with higher (better) role limitations due to physical health, energy/fatigue, and physical component scores over time in Residual Models.