. 2020 Dec 30;16(1):107–120. doi: 10.2215/CJN.09360620

Table 2.

Study characteristics of controlled trials examining the effect of phosphate-specific diet therapy delivered by a dietitian on primary outcomes in individuals with CKD on dialysis

Study	Population	Intervention	Control
Multicomponent, low-dose interventions
Ashurst et al. (32); United Kingdom; RCT (single-center, random by patient)	Sample size: 56/58 Vintage: >1 yr (not required) Age (mean [range], yr): 54 (22–88) Sex (female): 40% PO₄: ≥1 recent (3 mo) ≥5.3 mg/dl	Components Diet therapy (BL for 40 min) Diet ax: diet history Focus: LPD (NR) and binder adherence Behavior: NR Materials/handouts Tool for monitoring medications^a Booklet and magnets on LPD, binder, and dialysis Follow-up: monthly for 3 mo (graph and 3 mo mean) Maintenance: no additional	Components Usual care Diet therapy by renal dietitian Materials/handouts Tool for monitoring medications^a
Lim et al. (24); Korea; RCT (single-center, 2:1 ratio intervention-to-control, random by patient)^b	Sample size: 70/70 Vintage: ≥3 mo Age (mean [SD], yr): 59 (16) Sex (female): 47% PO₄: no requirement	Components Diet therapy (BL for 30 min) Diet ax: NR Focus: LPD (NR, additives) Behavior: lessons Pharmacist consult (BL for 30 min) Follow-up: 1 mo Maintenance: 2 mo	Components Usual care (NR)
Multicomponent, medium-dose interventions
Ford et al. (33); United States; RCT (multicenter [3], random by patient)	Sample size: 63/70 Vintage: NR Age: 74% >50 yr Sex (female): 62% PO₄: 3-mo mean ≥6.0 mg/dl^b	Components Diet therapy (1×/mo for 20–30 min) Diet ax: NR Focus: LPD (NR, protein foods, dairy products, additives), and binder and dialysis adherence Behavior: NR Materials/handouts Posters, handouts, and puzzles (NR); tool for monitoring serum phosphate Follow-up: 6 mo Maintenance: no additional	Components Usual care Diet therapy by renal dietitian
Morey et al. (26); United Kingdom; RCT (multicenter [NR], random by patient)	Sample size: (60–67)/67 (last obs.) Vintage: >6 mo Age (mean [SD], yr): intervention, 60 (16); control, 55 (16) Sex (female): 63% PO₄: 3-mo mean ≥5.6 mg/dl^c	Components Diet therapy (1×/mo, time NR) Diet ax: diet history Focus: LPD (NR) and binder adherence Behavior: individualized Follow-up: 6 mo Maintenance: 6 mo	Components Usual care Diet therapy by renal dietitian
Lou et al. (25); Spain; RCT (multicenter [5], random by center [4], and shift [1])	Sample size: 80/91 Vintage: >6 mo Age (mean [SD], yr): intervention, 61 (15); control, 63 (16) Sex (female): 48% PO₄: 3-mo mean >5.5 mg/dl^c	Components Diet therapy (1×/mo for 30 min) Diet ax: NR Focus: Mediterranean diet–based LPD (PBPF, dairy products, whole grains, additives, demineralization) Behavior: NR Materials/handouts Diet plans for LPD Follow-up: 6 mo Maintenance: no additional	Components Usual care (NR)
Multicomponent, high-dose interventions
Karavetian et al. (28); Lebanon; three-arm RCT (single-center, random by dialysis shift)	Sample size: 87/122 Vintage: ≥3 mo Age: 36% ≥65 yr Sex (female): 52% PO₄: no requirement	Components Diet therapy (2×/wk for 20 min, and 1×/mo for 10 min) Diet ax: NR Focus: LPD (NR, protein foods, dairy products, whole grains, additives) Behavior: self-management counseling Materials/handouts Interactive games (graded)^a Booklet on LPD and binders Follow-up: 8 wk Maintenance: no additional	Components control 1 (primary) Usual care Diet therapy with hospital dietitian (referral <1×/6 mo) Components control 2 Usual care Diet therapy with hospital dietitian (referral <1×/6 mo) Materials/handouts Interactive games (not graded)^a
Reese et al. (30); United States; three-arm RCT (multicenter [3], random by patients)	Sample size: 24/24 (diet-therapy and usual-care arms only) Vintage: NR Age (median [IQR], yr): intervention, 52 (47–58); control, 53 (50–55) Sex (female): 22% PO₄: 3-mo median >5.5 mg/dl^c with no hypophosphatemia (<3.5 mg/dl)	Components Diet therapy (BL for 45–60 min + ≥3×/wk [≥1×in-person or by telephone, time NR]) Diet ax: NR Focus: LPD (NR, protein foods, dairy products, whole grains, food preparation; not additives) and binder adherence Behavior: motivational interviewing and precaution adoption process model Follow-up: 10 wk Maintenance: no additional	Components Usual care Diet therapy with renal dietitian
Tsai et al. (34); Taiwan; nonrandomized study (single-center, allocated by patient [method NR])	Sample size: 61/68 Vintage: ≥6 mo Age (mean [SD], yr): intervention, 58 (11); control, 57 (12) Sex (female): 38% PO₄: 3-mo mean and most recent >5.5 mg/dl^c	Components Diet therapy (1×/2 wk for 30-min) Diet ax: 24-h recall Focus: LPD (NR, additives) and binder adherence Behavior: lessons with quizzes Materials/handouts Booklet (42 pages, HD diet, LPD, binders, dialysis, diet plan for LPD) Follow-up: 4 mo Maintenance: 4 mo	Components Usual care Education by dialysis nurses and physicians Materials/handouts Sheets on LPD
Rizk et al. (29) (NEMO trial); Lebanon; three-arm RCT (multicenter [12], 1:1 ratio intervention 1–to-control random by shift, 2:1 ratio intervention 2–to-control random by center)^d	Sample size: 545/570 Vintage: ≥3 mo Age (mean [SD], yr): interventions 1 and 2, 58 (15) and 61 (15) Control: 60 (15) Sex (female): 41% PO₄: no requirement	Components intervention 1 (primary) Trained study dietitians (32 h) Diet therapy (2×/wk for 15 min) Diet ax: NR Focus: LPD (NR, protein foods, dairy products, whole grains, additives), and binder and dialysis adherence Behavior: lessons, transtheoretic model, adherence contest Materials/handouts Recipe book, booklet on LPD, clinic poster on LPD^a Components intervention 2 Trained hospital dietitians (32 h) Follow-up: 6 mo Maintenance: 6 mo	Components Usual care Diet therapy by hospital dietitian (referral <1×/6 mo) Materials/handouts Clinic poster on LPD^a
Targeted interventions, phosphate additives
Sullivan et al. (27); United States; RCT (multicenter [14], random by shift)	Sample size: 279/279 (multiple imputation) Vintage: ≥6 mo Age (mean [SD] yr): intervention, 54 (13); control, 52 (12) Sex (female): 39% PO₄: 3-mo mean and most recent >5.5 mg/dl^c	Components Diet therapy (BL for 30-min + telephone in mo 2, time NR) Diet ax: NR Focus: Additives Behavior: NR Materials/handouts Case (additives list, magnifying glass), handout (fast food) Follow-up: 3 mo Maintenance: no additional	Components Usual care Diet therapy with renal dietitian
de Fornasari et al. (31); Brazil; RCT (single-center, random by patient)	Sample size: 131/140 Vintage: ≥6 mo Age (mean [SD] yr): intervention, 56 (13); control, 56 (15) Sex (female): 39% (n=134) PO₄: ≥3 recent (3 mo) ≥5.5 mg/dl^c	Components Diet therapy (1× between d 10–30 and 1× at d 45: time NR) Diet ax: dietary recalls (1), food records (3) at BL Focus: additives Behavior: NR Education by clinic dietitian (BL)^a Renal diet and LPD (NR, protein foods, dairy products, whole grains) Materials/handouts^a Booklet on LPD (NR) Follow-up: d 45 and 3 mo Maintenance: no additional	Components Usual care Diet therapy by renal dietitian Education by clinical dietitian (BL)^a Renal diet and LPD (NR, protein foods, dairy products, whole grains) Materials/handouts (BL)^a Booklet on LPD (NR)
Targeted interventions, meal preparation
Vrdoljak et al. (23); Croatia; RCT (single-center, random by patient)	Sample size: 47/50 Vintage: NR Age (median [IQR] yr): intervention, 73 (62–77); control, 68 (60–73) Sex: NR PO₄: >4.4 mg/dl^c or ↑ Ca⁺² or↑ PTH	Components Diet therapy (1×/wk for 2 mo, 15–20 mins)^a Diet ax: NR Focus: demineralization Behavior: NR Meals (two meals per dialysis, demineralized) Diet therapy (BL ×3 d+1×/week for 2 mo, 15 min) Diet ax: NR Focus: HD diet, LPD (NR, plant-rich, additives) Behavior: lessons Materials/handouts^a Handouts (HD diet, LPD, menus) Follow-up: monthly up to 12 mo (graph only, NR) Maintenance: no additional	Components Usual care NR Meals (two meals per dialysis, prepared normally) Diet therapy (BL ×3 d+1×/wk for 2 mo, 15 min)^a Diet ax: NR Focus: HD diet, LPD (NR, plant rich, additives) Behavior: lessons Materials/handouts^a Handouts (HD diet, LPD, menus)

RCT, randomized controlled trial; PO₄, phosphate; BL, baseline; ax, assessment; LPD, low-protein diet; NR, not reported; obs., observation; PBPF, plant-based protein foods; IQR, interquartile range; HD, hemodialysis; Ca²⁺, calcium ion; PTH, parathyroid hormone.

Interventions that span two or more groups (also indicated in italics).

The primary outcome in Lim, et al. (24) was calcium-phosphate product. However, use of this outcome is discouraged by Kidney Disease Improving Global Outcomes (1) and, therefore, this study reported the secondary outcome of phosphate levels.

Conversion factors for units: serum phosphate levels in mg/dl to mmol/L ×3.096.

Results from the NEMO trial were extracted from Rizk et al. (29) PMID 28657451, which reported effects on the total cohort. A subanalysis of individuals with hyperphosphatemia was reported in Rizk et al. (29) PMID 28322468, but results were not different in this subgroup.