Food Frequency Questionnaire to Estimate Dietary Adherence in Hemodialysis Patients: A Pilot Study

Background/Objectives: Stage 5 chronic kidney disease (CKD), or end-stage renal disease (ESRD), requires renal replacement therapy, commonly hemodialysis (HD). This treatment necessitates dietary changes due to impaired excretory function and protein-energy wasting (PEW). A structured diet with adequate energy, protein, electrolytes, and fluids is essential. The aim was to characterize habitual dietary intake in adults on HD relative to KDOQI and ESPEN recommendations. Methods: In this cross-sectional study, 50 adults on maintenance HD at the Medical University of Warsaw completed a validated Food Frequency Questionnaire (55 items, nine frequency categories). The study was questionnaire-based and did not collect, link, or analyze dialysis efficacy indices, residual diuresis, or anthropometric measurements; all dietary estimates are independent of these clinical parameters. Estimated intakes of energy, macronutrients, fiber, electrolytes (Na, K, Ca, P), and fluids were compared with KDOQI 2020 and ESPEN 2021 recommendations. Sensitivity analyses included deterministic scenarios and Monte Carlo simulations. Results: Mean intakes were 2696.9 ± 1392.7 kcal and 87.7 ± 35.3 g protein; 64% and 82% met reference values. Sensitivity analyses revealed per-kg shortfalls in heavier patients (>75 kg): Monte Carlo medians were 37.8 kcal/kg/day and 1.28 g/kg/day. Diets were fat-dominant (~46%E), with low carbohydrates (~40%E) and low fiber, about 8 g per 1000 kcal. Sodium and phosphorus were elevated, about 1119 mg and 498 mg per 1000 kcal, while calcium was low (~346 mg/1000 kcal). Conclusions: Despite adequate mean intake, sensitivity analyses revealed per-kg energy/protein deficits and elevated sodium and phosphorus. Individualized counseling with electrolyte and fluid management, greater dietary diversity, and psychosocial support is warranted in HD.