Effects of dietary intake, appetite, and eating habits on dialysis and non-dialysis treatment days in hemodialysis patients: cross-sectional results From the HEMO study

Effects of Dietary Intake, Appetite, and Eating Habits on Dialysis and Non–Dialysis Treatment Days in Hemodialysis Patients: Cross-Sectional Results From the HEMO Study Jerrilynn D. Burrowes, PhD, RD,* Brett Larive, MS,† David B. Cockram, PhD, RD,‡ Johanna Dwyer, DSc, RD,§ John W. Kusek, PhD,¶ Sandra McLeroy, MS, RD,㛳 Diane Poole, RD,** and Michael V. Rocco, MD, MS,†† and the Hemodialysis (HEMO) Study Group Objective: To evaluate differences between dietary energy intake (DEI), dietary protein intake (DPI), appetite, dietary patterns, and eating habits during dialysis treatment days (DD) and non– dialysis treatment days (NDD) in 1,901 adults receiving maintenance hemodialysis who were enrolled in the baseline phase of the National Institutes of Health–sponsored Hemodialysis (HEMO) study. Design: A cross-sectional analysis of participants at baseline (before randomization). Setting: Fifteen clinical centers across the United States. Measurements: DEI, DPI, and self-reported assessment of appetite, dietary patterns, and eating habits. Results: For the entire study cohort, total mean (⫾ SD) DEI (1,566 ⫾ 636 kcal/day) and weight-adjusted DEI (23.2 ⫾ 9.5 kcal/kg/day) were significantly higher (P ⬍ .0001) on NDD than on DD (1,488 ⫾ 620 kcal/day and 22.2 ⫾ 9.6 kcal/kg/day), respectively. Similarly, DPI was significantly higher (P ⬍ .0001) on NDD (65.0 ⫾ 29.0 g/day and 0.96 ⫾ 0.43 g/kg/day) than on DD (60.2 ⫾ 26.5 g/day and 0.90 ⫾ 0.41 g/kg/day). On DD and NDD, the mean weight-adjusted DEI for the entire cohort was less than the HEMO study standard of care (SOC) of ⱖ28 kcal/kg/day, whereas on NDD, several subgroups reported dietary protein intakes that were closer to the study’s SOC. These included men, patients under 50 years of age, nonblack participants, those without diabetes, those with a normal or mild Index of Co-Existing Disease score, and those on dialysis for more than 5 years. Protein and energy intakes declined with worsening self-reported appetites in both DD and NDD after adjusting for other subgroup effects. Conclusion: Dietary energy and protein intakes of HEMO study participants were lower on DD than on NDD, and also lower than the SOC on both days, particularly with regard to energy intake. People receiving maintenance hemodialysis should be counseled to consume adequate amounts of energy and protein daily, especially on DD. Practitioners should monitor closely those patients who report poor appetite and should intervene appropriately. © 2003 by the National Kidney Foundation, Inc.

P

ROTEIN-ENERGY MALNUTRITION (PEM) is a major risk factor for adverse health outcomes in maintenance hemodialysis patients. There are many causes of PEM in these

patients, and they may be attributed to nutritional, clinical, social, economic, pharmacologic, and/or treatment-related factors. These include, but are not limited to, increased catabolism, im-

*Division of Nephrology and Hypertension, Beth Israel Medical Center, New York, NY. †Department of Biostatistics and Epidemiology, The Cleveland Clinic Foundation, Cleveland, OH. ‡Regulatory Affairs, Ross Products Division, Abbott Laboratories, Columbus, OH. §Frances Stern Nutrition Center, New England Medical Center, and Tufts University Schools of Medicine and Nutrition, Boston, MA. ¶Division of Kidney, Urologic, and Hematologic Diseases of the National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD. 㛳Division of Nephrology, Vanderbilt University Medical Center, Nashville, TN. **Piedmont Dialysis Center, Winston-Salem, NC.

††Section on Nephrology, Wake Forest University School of Medicine, Winston-Salem, NC. Supported by the National Institute of Diabetes, Digestive and Kidney Diseases (NIDDK) of the National Institutes of Health. Baxter Healthcare Corporation (McGaw Park, IL) and Fresenius Medical Care-North America (Lexington, MA) provided some study dialyzers. Nutritional supplements were provided by Abbott Laboratories, Ross Product Division (Columbus, OH), and multivitamins by R & D Laboratories, Inc (Marina del Rey, CA). Address reprint requests to Jerrilynn D. Burrowes, PhD, RD, Department of Nutrition, C. W. Post Campus, Long Island University, 720 Northern Blvd, Brookville, NY 11548-1300. © 2003 by the National Kidney Foundation, Inc. 1051-2276/03/1303-0004$30.00/0 doi:10.1016/S1051-2276(03)00069-4

Journal of Renal Nutrition, Vol 13, No 3 ( July), 2003: pp 191-198

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balances in protein and energy metabolism, abnormalities in amino acid metabolism, acidosis, membrane bioincompatibility, loss of amino acids into the dialysate, and inadequate nutrient intake.1,2 Other factors such as dialysis unit policies prohibiting eating during dialysis, the duration of dialysis, and the time spent commuting to and from the treatment center may also play a role in reduced dietary intakes. Although previous reports have shown that dietary energy intake (DEI) and dietary protein intake (DPI) are reduced on dialysis treatment days (DD) compared with non– dialysis treatment days (NDD),3 the magnitude of these differences and the factors associated with their variations have not been well studied. Identifying risk factors responsible for diminished DEI and DPI between DD and NDD may provide important insight into how PEM may be prevented in the hemodialysis population. The relationships between DEI, DPI, appetite, and patient self-reported dietary patterns and eating habits on DD and NDD were examined cross-sectionally in a large cohort of maintenance hemodialysis patients participating in the baseline phase of a multicenter clinical trial. The large cohort offered a broad case mix that afforded further subgroup analyses.

Methods Study Design The Hemodialysis (HEMO) study was a 7-year, prospective, multicenter, randomized clinical trial sponsored by the National Institutes of Health (NIH). The objective of the HEMO study was to determine the effects of dialysis dose (standard equilibrated Kt/V [eKt/V] of 1.05 versus high eKt/V of 1.45) and membrane flux (high [␤2 microglobulin (␤2M) clearance ⬎20 mL/ min] versus low [␤2M clearance ⬍10 mL/min]) on mortality and morbidity in maintenance hemodialysis patients. Specific details of the study design have been published elsewhere.4 Briefly, subjects enrolled in the baseline phase of the trial were 18 to 80 years of age, had been on chronic dialysis for at least 3 months, were receiving maintenance hemodialysis 3 times per week, and had a residual renal function of less than 1.5 mL/min/35 L of urea distribution. Among the exclusion criteria relevant to this analysis were

severe malnutrition (defined as a predialysis serum albumin concentration ⬍2.6 g/dL, as measured by nephelometry), severe cardiac disease, malignancies currently requiring chemotherapy or radiation therapy, known acquired immunodeficiency syndrome (AIDS), or inability or unwillingness to participate in the procedures of the protocol (eg, maintain diet records). The HEMO study included only patients who were able to attain an eKt/V of 1.45 in 4.5 hours or less, or an anthropometric volume (V) of less than 47 L (this excluded from enrollment individuals with body weights in excess of about 90 kg, approximately 9% of subjects). The Institutional Review Boards at each clinical center approved the study protocol. Written informed consent was obtained from each study participant.

Study Population People enrolled at baseline (n ⫽ 1,901) with complete information were included in this analysis. Participants were enrolled from March 1995 to February 2001 from 72 hemodialysis units associated with the 15 clinical centers.5 Data Collection Dietary energy intake, dietary protein intake, self-reported assessment of appetite, and patientreported dietary patterns and eating habits were obtained at baseline when participants were receiving their usual dialysis prescription (mean eKt/V, 1.41 ⫾ 0.24; mean single-pool [sp] Kt/V, 1.57 ⫾ 0.27) and were treated with their usual dialysis membranes. Sex, age, race, diabetes status, Index of Co-Existing Disease (ICED) score, and number of years on dialysis were obtained either by personal interview or by medical chart review. Determination of DEI and DPI Participants completed 2-day diet diary-assisted recalls (also referred to as diet records) after receiving instruction from the HEMO study dietitian on maintaining a diet diary. Patients recorded their food and beverage intake, including oral enteral supplements, during an assigned 2-day period. All study dietitians received standardized training in the collection and review of the diet diaries and on the use of the nutrient analysis software. The diet diaries were analyzed according to a standardized protocol6-8 for DEI and DPI at each clinical center using customized software of the Nutritionist IV or Five Programs

DIETARY INTAKE IN HEMODIALYSIS PATIENTS

(First Data Bank, San Bruno, CA). For participants enrolled from March 1995 to July 1999, Nutritionist IV, Version 4.0, was used. Nutritionist Five, Versions 2.0h to 2.1h, were used for individuals enrolled from August 1999 to February 2001. Diet records were collected for 2 consecutive days. The relationship between body weight and nutrient intake was determined from actual weight if body weight was between 90% and 120% of median standard body weight (SBW) as determined from the National Health and Nutrition Examination Survey II (NHANES II) data.9 If actual body weight was ⬍90% or ⬎120% of SBW, energy and protein intakes were normalized to an adjusted body weight (ABW) to standardize nutrient intake using the formula: ABW ⫽ ([Actual weight ⫺ SBW)] ⫻ 0.25) ⫹ SBW. The HEMO study established minimal intakes of both DEI and DPI (ie, standards of care [SOC]) to identify patients in need of increased nutritional intake and attention by the study dietitian and to facilitate the provision of study medical nutrition supplements. The SOC for weight-adjusted energy and protein intakes were 28 kcal/kg/day or greater and 1.0 g/kg/day or greater, respectively.6

Determination of DD and NDD Information concerning DD or NDD was not collected in conjunction with the diet records until the HEMO study’s fourth year (April 1999). This meant that the type of treatment day (DD or NDD) had to be inferred retrospectively for the early records by comparing the regular weekday patterns of other monthly dialysis records (patients were dialyzed either Monday, Wednesday, and Friday, or Tuesday, Thursday, and Saturday) with the weekdays of the 2-day diet records. This designation comprised 72.7% of all the baseline diet records collected. Ninety-seven percent of the nondesignated diet records were assigned their treatment day status through this comparison. The retrospective designations were compared with the prospective indicators collected from the fourth year of the study forward; the two assignments agreed in 97.3% of the cases. Assessment of Appetite, Dietary Patterns, and Other Measures Self-assessed appetite was evaluated with the Appetite and Diet Assessment Tool (ADAT).10 In this tool, 30 questions ask about the general

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level of appetite and eating habits, and 7 ask about appetite and eating habits on both DD and NDD. Study dietitians administered the ADAT during the dialysis treatment. Subjective assessment of appetite was rated on a 5-point Likert scale: very good, good, fair, poor, or very poor. Other dietary information obtained from the ADAT included use of oral enteral supplements, desire to change the diet, difficulty following the diet, eating habits during the dialysis treatment, and responsibility for food shopping and food preparation. The ICED score was obtained at baseline to provide an assessment of the participant’s comorbidity status. ICED is a composite comorbidity coding system that classifies the presence and severity of diseases and the impact of disease on physical function.11 The instrument classifies the functional impact of diseases as normal, mild, moderate, or severe. For this analysis, ICED scores of normal and mild were combined into one category as normal or mild; the other categories, moderate and severe, were not combined.

Analytical Methods Baseline characteristics and intake levels are presented as mean (standard deviation) for quantitative variables and as count (percentage) for categorical variables. Subgroup analyses were performed to identify groups with different trends in nutritional status between DD and NDD. The subgroups were chosen a priori. Intake differences between DD and NDD were assessed for the entire cohort and within subgroups using paired t tests. Intakes were compared between dichotomous subgroups using Student’s unpaired t tests and between ordinal subgroups using Jockheere-Terpstra tests. To determine whether any of the subgroup effects were independently associated with treatment day– specific intakes or the differences, multivariable analyses were conducted using repeated measures analysis of variance (ANOVA). Appetite assessment scores were compared for the entire cohort and within subgroups using marginal homogeneity tests. Subgroup comparisons specific to DD or NDD scores or their differences were assessed using Cochrane-Mantel-Haenszel correlation tests for ordinal groups and ANOVA for dichotomous categories. Associations between appetite scores and nutritional intakes were tested univariately using

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Table 1. Total Dietary Energy Intake (kcal/day) and Weight-Adjusted Dietary Energy Intake (kcal/kg/day) Between Dialysis and Nondialysis Treatment Days in HEMO Study Participants at Baseline (Mean ⫾ SD) Variable

Overall cohort Sex Men Women Age group (y) Less than 50 50 to 64 Greater than 64 Race Black Nonblack Presence of diabetes Absent Present ICED score Normal or mild Moderate Severe Years on dialysis Less than 2 2 to 5 More than 5

N

Dietary Energy Intake (kcal/day and kcal/kg/day)

DD and NDD Combined

DD

P Value*

NDD

P Value†

Difference‡

1,901

1,527 ⫾ 551 (22.7 ⫾ 8.3)

1,488 ⫾ 620 (22.2 ⫾ 9.6)

–

1,566⫾ 636 (23.2 ⫾ 9.5)

–

77.5 ⫾ 603 (1.02 ⫾ 9.2)

857 1,044

1,722 ⫾ 577 (23.8 ⫾ 8.4) 1,367 ⫾ 472 (21.7 ⫾ 8.1)

1,686 ⫾ 646 (23.4 ⫾ 9.7) 1,326 ⫾ 547 (21.1 ⫾ 9.4)

⬍.001

1,759 ⫾ 684 (24.3 ⫾ 9.7) 1,407 ⫾ 546 (22.3 ⫾ 9.2)

⬍.001

73.2 ⫾ 663 (0.83 ⫾ 9.3) 81.0 ⫾ 550 (1.18 ⫾ 9.1)

549 647 705

1,720 ⫾ 611 (25.4 ⫾ 9.3) 1,475 ⫾ 515 (21.7 ⫾ 7.8) 1,425 ⫾ 493 (21.4 ⫾ 7.6)

1,673 ⫾ 685 (24.9 ⫾ 10.9) 1,432 ⫾ 583 (21.1 ⫾ 8.9) 1,396 ⫾ 568 (21.0 ⫾ 8.6)

⬍.001

1,767 ⫾ 733 (26.0 ⫾ 10.6) 1,517 ⫾ 599 (22.3 ⫾ 9.0) 1,454 ⫾ 545 (21.9 ⫾ 8.5)

⬍.001

94.6 ⫾ 721 (1.06 ⫾ 10.9) 84.7 ⫾ 581 (1.13 ⫾ 8.9) 57.5 ⫾ 518 (0.90 ⫾ 8.1)

1,190 711

1,502 ⫾ 550 (22.3 ⫾ 8.4) 1,569 ⫾ 550 (23.3 ⫾ 8.2)

1,455 ⫾ 619 (21.6 ⫾ 9.6) 1,445 ⫾ 617 (23.1 ⫾ 9.5)

.002

1,550 ⫾ 640 (23.0 ⫾ 9.7) 1,593 ⫾ 629 (23.6 ⫾ 9.1)

NS

94.9 ⫾ 613 (1.33 ⫾ 9.4) 48.3 ⫾ 587 (0.51 ⫾ 8.8)

1,045 856

1,641 ⫾ 583 (24.5 ⫾ 8.8) 1,388 ⫾ 473 (20.5 ⫾ 7.1)

1,609 ⫾ 660 (24.1 ⫾ 10.2) 1,342 ⫾ 533 (19.9 ⫾ 8.2)

⬍.001

1,674 ⫾ 678 (24.9 ⫾ 10.1) 1,434 ⫾ 553 (21.1 ⫾ 8.2)

⬍.001

65.6 ⫾ 654 (0.83 ⫾ 10.0) 92.0 ⫾ 536 (1.26 ⫾ 8.2)

643 546 603

1,587 ⫾ 547 (23.4 ⫾ 8.3) 1,504 ⫾ 546 (22.5 ⫾ 8.3) 1,484 ⫾ 544 (22.2 ⫾ 8.4)

1,562 ⫾ 627 (23.1 ⫾ 9.7) 1,463 ⫾ 619 (22.0 ⫾ 9.7) 1,441 ⫾ 605 (21.7 ⫾ 9.6)

.007

1,612 ⫾ 624 (23.6 ⫾ 9.3) 1,545 ⫾ 644 (23.1 ⫾ 9.8) 1,527 ⫾ 625 (22.8 ⫾ 9.4)

.052

49.7 ⫾ 607 (0.57 ⫾ 9.2) 81.7 ⫾ 635 (1.10 ⫾ 9.9) 86.6 ⫾ 574 (1.15 ⫾ 8.7)

914 561 426

1,478 ⫾ 522 (21.9 ⫾ 7.9) 1,523 ⫾ 561 (22.5 ⫾ 8.3) 1,638 ⫾ 583 (24.7 ⫾ 8.9)

1,440 ⫾ 593 (21.3 ⫾ 9.1) 1,500 ⫾ 624 (22.3 ⫾ 9.5) 1,577 ⫾ 660 (23.9 ⫾ 10.5)

⬍.001

1,516 ⫾ 603 (22.4 ⫾ 9.1) 1,546 ⫾ 645 (22.8 ⫾ 9.4) 1,700 ⫾ 676 (25.5 ⫾ 10.1)

⬍.001

75.6 ⫾ 585 (1.04 ⫾ 8.9) 45.9 ⫾ 593 (0.60 ⫾ 9.0) 123 ⫾ 654 (1.5 ⫾ 10.1)

NOTE. Values in parentheses are weight-adjusted. P values ⬍ .05 were considered statistically significant. Within each subgroup, the differences were all significant at the P ⬍ .01 level except for patients with “normal” or “mild” ICED scores and patients who had been on dialysis for between 2 and 5 years. Abbreviations: DD, dialysis treatment day; NDD, nondialysis treatment day. *P values for differences in energy intake between subgroups on dialysis days. †P values for differences in energy intake between subgroups on nondialysis days. ‡Nondialysis day (NDD) values minus dialysis day (DD) values all differed between subgroup categories at P ⬍ .0001.

repeated measures ANOVA and modeling the appetite scores as a continuous measure with DD and NDD intakes modeled separately. In light of the strong univariate associations found, multivariable models were used to test whether the associations held after controlling for effects of the other subgroup factors. In contrast to the univariate tests, these analyses compared intakes by specific appetite categories. P values ⬍.05 were considered statistically significant without adjusting for multiple comparisons. All analyses were carried out with SAS for Unix 8.0 (SAS Institute, Inc, Cary, NC).

Results In all patients combined, the mean (⫾ SD) age of the cohort was 57.5 ⫾ 14.1 years. The mean postdialysis body weight and body mass index (BMI) were 69.5 ⫾ 15.0 kg and 25.6 ⫾ 5.4 kg/m2, respectively. This average weight and BMI is likely to be less than that of the typical U.S. hemodialysis patient12 because the HEMO study excluded patients who could not achieve the high Kt/V goal in 4.5 hours, effectively

limiting the weight of study participants to ⬍90 kg.

Dietary Intake Tables 1 and 2 present comparisons of DD versus NDD intakes for total and weight-adjusted DEI and DPI, respectively. Mean DEI and DPI for the study cohort were significantly higher (P ⬍ .0001) on NDD compared with DD (DEI difference: 77.5 ⫾ 603 kcal/day and 1.02 ⫾ 9.2 kcal/kg/day; DPI difference: 4.79 ⫾ 30.6 g/day and 0.07 ⫾ 0.46 g/kg/day). On both DD and NDD, the weight-adjusted DEI for the entire cohort and for all subgroups was lower than the trial’s SOC of ⱖ28 kcal/kg/day. On NDD, select subgroups had average weight-adjusted DPIs approaching the SOC of 1.0 g/kg/day (see Table 2). These included men (1.0 ⫾ 0.44 g/kg/day), younger participants (⬍50 years of age) (1.0 ⫾ 0.48 g/kg/day), those without diabetes (0.99 ⫾ 0.45 g/kg/day), those with a normal or mild ICED score (0.99 ⫾ 0.45 g/kg/day), and those receiving dialysis for more than 5 years (1.0 ⫾ 0.43 g/kg/day). Inadequate weight-adjusted DEI and DPI were noted on DD in women (21.1 ⫾

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Table 2. Total Dietary Protein Intake (g/day) and Weight-Adjusted Dietary Protein Intake (g/kg/day) Between Dialysis and Nondialysis Treatment Days in HEMO Study Participants at Baseline (Mean ⫾ SD) Variable

Overall cohort Sex Men Women Age group (y) Less than 50 50 to 64 Greater than 64 Race Black Nonblack Presence of diabetes Absent Present ICED score Normal or mild Moderate Severe Years on dialysis Less than 2 2 to 5 More than 5

N

Dietary Protein Intake (g/day and g/kg/day)

DD and NDD Combined

DD

P Value*

NDD

P Value†

Difference‡

1,901

62.6 ⫾ 23.2 (0.93 ⫾ 0.35)

60.2 ⫾ 26.5 (0.90 ⫾ 0.41)

–

65.0 ⫾ 29.0 (0.96 ⫾ 0.43)

–

4.79 ⫾ 30.6 (0.06 ⫾ 0.46)

857 1,044

70.1 ⫾ 24.6 (0.97 ⫾ 0.36) 56.5 ⫾ 19.9 (0.90 ⫾ 0.34)

67.9 ⫾ 28.1 (0.95 ⫾ 0.42) 53.9 ⫾ 23.2 (0.86 ⫾ 0.39)

⬍.001

72.2 ⫾ 31.3 (1.00 ⫾ 0.44) 59.1 ⫾ 25.5 (0.94 ⫾ 0.42)

.002

4.27 ⫾ 33.4 (0.05 ⫾ 0.46) 5.23 ⫾ 28.1 (0.08 ⫾ 0.45)

549 647 705

66.5 ⫾ 25.1 (0.99 ⫾ 0.38) 62.5 ⫾ 23.3 (0.92 ⫾ 0.35) 59.7 ⫾ 20.9 (0.90 ⫾ 0.33)

63.4 ⫾ 27.8 (0.95 ⫾ 0.44) 60.5 ⫾ 27.2 (0.89 ⫾ 0.41) 57.5 ⫾ 24.3 (0.87 ⫾ 0.38)

.003

69.6 ⫾ 32.7 (1.00 ⫾ 0.48) 64.5 ⫾ 28.7 (0.95 ⫾ 0.42) 61.8 ⫾ 25.6 (0.93 ⫾ 0.40)

⬍.001

6.19 ⫾ 34.3 (0.08 ⫾ 0.50) 4.07 ⫾ 30.8 (0.06 ⫾ 0.46) 4.37 ⫾ 27.2 (0.07 ⫾ 0.42)

1,190 711

62.4 ⫾ 23.6 (0.92 ⫾ 0.35) 63.0 ⫾ 22.5 (0.94 ⫾ 0.35)

59.8 ⫾ 27.0 (0.89 ⫾ 0.41) 60.8 ⫾ 25.4 (0.91 ⫾ 0.41)

NS

64.9 ⫾ 29.2 (0.96 ⫾ 0.43) 65.2 ⫾ 28.7 (0.97 ⫾ 0.43)

NS

5.04 ⫾ 30.7 (0.07 ⫾ 0.46) 4.38 ⫾ 30.4 (0.06 ⫾ 0.45)

1,045 856

64.3 ⫾ 23.9 (0.96 ⫾ 0.37) 60.5 ⫾ 22.0 (0.859 ⫾ 0.33)

62.2 ⫾ 27.3 (0.93 ⫾ 0.42) 57.8 ⫾ 25.2 (0.85 ⫾ 0.38)

⬍.001

66.4 ⫾ 30.3 (0.99 ⫾ 0.45) 63.3 ⫾ 27.3 (0.93 ⫾ 0.41)

.004

4.19 ⫾ 32.2 (0.06 ⫾ 0.48) 5.54 ⫾ 28.5 (0.08 ⫾ 0.43)

643 546 603

64.7 ⫾ 24.1 (0.95 ⫾ 0.36) 61.6 ⫾ 23.2 (0.92 ⫾ 0.35) 60.9 ⫾ 21.7 (0.92 ⫾ 0.35)

62.0 ⫾ 26.8 (0.92 ⫾ 0.40) 59.1 ⫾ 25.9 (0.89 ⫾ 0.40) 58.8 ⫾ 26.2 (0.89 ⫾ 0.42)

NS

67.4 ⫾ 30.8 (0.99 ⫾ 0.45) 64.1 ⫾ 29.9 (0.96 ⫾ 0.44) 63.0 ⫾ 25.6 (0.95 ⫾ 0.41)

NS

5.34 ⫾ 31.8 (0.07 ⫾ 0.46) 5.03 ⫾ 31.5 (0.07 ⫾ 0.48) 4.12 ⫾ 28.3 (0.06 ⫾ 0.43)

914 561 426

62.5 ⫾ 22.8 (0.92 ⫾ 0.34) 61.9 ⫾ 24.2 (0.92 ⫾ 0.36) 63.7 ⫾ 22.6 (0.96 ⫾ 0.37)

59.6 ⫾ 25.5 (0.89 ⫾ 0.39) 61.0 ⫾ 27.7 (0.90 ⫾ 0.42) 60.5 ⫾ 27.0 (0.92 ⫾ 0.43)

NS

65.4 ⫾ 29.4 (0.96 ⫾ 0.43) 62.9 ⫾ 29.4 (0.93 ⫾ 0.43) 66.9 ⫾ 27.5 (1.01 ⫾ 0.43)

NS

5.79 ⫾ 30.8 (0.08 ⫾ 0.46) 1.91 ⫾ 30.4 (0.03 ⫾ 0.45) 6.45 ⫾ 30.3 (0.09 ⫾ 0.45)

NOTE. Values in parentheses are weight-adjusted. P values ⬍ .05 were considered statistically significant. Within each subgroup, the differences were all significant at the P ⬍ .01 level except for patients who had been on dialysis between 2 and 5 years. Abbreviations: DD, dialysis treatment day; NDD, nondialysis treatment day. *P values for differences in energy intake between subgroups on dialysis days. †P values for differences in energy intake between subgroups on nondialysis days. ‡Nondialysis day (NDD) values minus dialysis day (DD) values all differed between subgroup categories at P ⬍ .0001.

9.4 kcal/kg/day and 0.86 ⫾ 0.39 g/kg/day), older participants (more than 64 years of age) (21.0 ⫾ 8.6 kcal/kg/day and 0.87 ⫾ 0.38 g/kg/ day), blacks (21.6 ⫾ 9.6 kcal/kg/day and 0.89 ⫾ 0.41 g/kg/day), those with severe comorbid disease (21.7 ⫾ 9.6 kcal/kg/day and 0.89 ⫾ 0.42 g/kg/day), and those receiving dialysis for ⬍2 years (21.3 ⫾ 9.1 kcal/kg/day and 0.89 ⫾ 0.39 g/kg/day), respectively. The lowest means for weight-adjusted DEI and DPI were reported by people with diabetes on DD (19.9 ⫾ 8.2 kcal/ kg/day and 0.85 ⫾ 0.38 g/kg/day, respectively).

Subjective Assessment of Appetite A significant proportion of participants reported better appetites (very good and good) on NDD (76%) than on DD (63%). Those subgroups reporting higher dietary energy and protein intakes also indicated having a larger percentage of participants with very good and good appetites on both DD and NDD (men, 71.3%; younger participants, 70.5%; those without diabetes, 70.3%; those with normal or mild ICED scores, 72.9%; and those on dialysis ⬍2 years, 67.9%). The appetite differential between DD and NDD differed significantly between sub-

groups except between black and nonblack race and between the ICED score groups (data not shown). In separate univariate analyses for DD and NDD, increasing appetite assessment scores, treated as continuous measures, were associated significantly with increasing DEI and DPI (P ⬍ .05 for all four tests [protein for DD and NDD, energy for DD and NDD]). A multivariable approach compared mean intakes between individual appetite categories controlling for age, sex, black race, diabetes status, ICED score, and duration of dialysis (Table 3). The results showed that dietary intakes declined steadily with poorer appetite scores, for the most part, but that significant differences were confined primarily to the DD appetite scores that were farthest apart (ie, DEI on DD, very good versus very poor difference: 5.7 ⫾ 1.4 kcal/kg/day; DPI on DD, very good versus very poor difference: 0.11 ⫾ 0.06 g/kg/day).

Diet and Eating Habits Dietary patterns and eating habits measured included frequency of meals and snacks eaten daily and whether the patient ate during the

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Table 3. Weight-Adjusted Dietary Energy and Protein Intakes (and 95% Confidence Intervals) by Level of Self-Reported Assessment of Appetite in HEMO Study Participants at Baseline (n ⫽ 1,897) Self-Reported Appetite Rating

Very good Good Fair Poor Very poor

DD (%)

NDD (%)

27.0 35.7 24.5 10.0 2.7

31.7 44.0 18.9 4.2 1.2

Dietary Energy Intake (kcal/kg/day) DD

P Value*

23.2 (22.4, 24.1) – 22.8 (22.1, 23.5) .45 22.1 (21.2, 22.9) .058 20.3 (19.9, 21.7) .0004 17.5 (14.9, 20.1) ⬍.0001

Dietary Protein Intake (g/kg/day)

NDD

P Value*

23.4 (22.6, 24.3) 23.6 (22.9, 24.3) 22.8 (21.9, 23.6) 22.3 (21.0, 23.7) 21.5 (19.0, 24.1)

– .77 .29 .19 .17

DD

P Value*

NDD

0.92 (0.88, 0.96) – 0.98 (0.94, 1.02) 0.92 (0.89, 0.96) .87 0.97 (0.94, 1.01) 0.90 (0.86, 0.94) .41 0.97 (0.93, 1.01) 0.82 (0.76, 0.88) .0048 0.90 (0.84, 0.96) 0.81 (0.66, 0.96) .0003 0.89 (0.77, 1.01)

P Value* – .75 .71 .04 .16

NOTE. Values in parentheses represent 95% confidence intervals (CI). P values ⬍ .05 were considered statistically significant. Abbreviations: DD, dialysis treatment days; NDD, nondialysis treatment days. *P values for comparison with very good rating.

dialysis treatment. The cross-tabulations of these factors showed trends consistent with the increased dietary intakes on NDD. Forty-eight percent of participants consumed 3 to 5 meals daily on DD, whereas 64% reported eating the same amount of meals on NDD. Eleven percent of patients reported either not eating or consuming only 1 meal per day on DD, compared with 5% on NDD. Approximately half of the subjects relied on others for food shopping and food preparation (52% and 49%, respectively). Participants who had assistance with food shopping consumed more dietary energy and protein on both DD and NDD compared with those who were not assisted (DEI on DD: 22.5 ⫾ 9.8 versus 21.9 ⫾ 9.4 kcal/kg/day, P ⫽ NS; DEI on NDD: 23.9 ⫾ 10.0 versus 22.6 ⫾ 9.4 kcal/kg/day, P ⫽ .0008; DPI on DD: 0.90 ⫾ 0.42 versus 0.89 ⫾ 0.39 g/kg/day, P ⫽ .013; DPI on NDD: 0.99 ⫾ 0.97 versus 0.94 ⫾ 0.42 g/kg/day, P ⫽ .012). On NDD, patients who received assistance with food preparation reported significantly higher energy but not protein intakes compared with those who were not assisted (DEI: 23.7 ⫾ 8.9 versus 22.6 ⫾ 8.7 kcal./kg/day, P ⫽ .0007, and DPI: 0.98 ⫾ 0.45 versus 0.95 ⫾ 0.42 g/kg/day, P ⫽ .072). No such differences were observed on DD (data not shown). Patients who ate during dialysis (41%) showed no significant DEI differences between DD and NDD (DD, 23.0 ⫾ 9.2 kcal/kg/day; NDD, 23.3 ⫾ 9.4 kcal/kg/day, P ⫽ .065), although the DPI differences were significant (DD, 0.88 ⫾ 0.41 g/kg/day; NDD, 0.94 ⫾ 0.44 g/kg/day, P ⬍ .0001). Furthermore, these patients reported higher intakes than patients who did not eat during dialysis (59%), but the differences were not statistically significant (data not shown). This

suggests that patients who ate during dialysis chose to eat high-calorie, low-protein foods. In fact, 80% of those who ate during dialysis reported consuming 1 to 4 or more snacks per DD, compared with 67.5% among those who did not eat during dialysis.

Discussion Several important observations were made in this cross-sectional study. First, the mean weightadjusted dietary energy and protein intakes diminished significantly from NDD to DD, with DEI diminishing by 77.5 kcal/day or 1.02 kcal/ kg/day and DPI diminishing by 4.79 g/day or 0.06 g/kg/day (see Tables 1 and 2, respectively). The clinical significance of long-term deficits in dietary energy and protein intakes on DD is not known. However, even small, sustained differences in intakes may be important, especially when patients’ intakes are likely to be hypocaloric (ie, the mean dietary energy intake of the study cohort was 23 kcal/kg/day). An energy deficit of 77.5 kcal per DD amounts to an estimated annual deficit of 12,500 kcal. Furthermore, the catabolic effects of the dialysis treatment per se and the physiologic and metabolic effects of dialysis on the body (eg, cytokine release following contact between the blood and the dialysis membrane) may exacerbate poor nutritional status and contribute to lower dietary intakes on DD, or may exacerbate the effects of an already suboptimal diet. Feelings of fatigue or tiredness after dialysis may also contribute to deficient intakes on DD. These findings may suggest a potential benefit for on-dialysis nutritional interventions and, where patients are permitted to eat during dialysis, a need to help patients make appropriate food choices.

DIETARY INTAKE IN HEMODIALYSIS PATIENTS

Second, in terms of clinical standards, dietary intakes on NDD were below the National Kidney Foundation Kidney Disease Outcomes Quality Initiative (NKF-K/DOQI) nutrition recommendations of 35 kcal/kg/day for DEI and 1.2 g/kg/day for DPI,13 and also the less-stringent HEMO SOC of ⱖ28 kcal/kg/day for DEI and ⱖ1.0 g/kg/day for DPI. The average reported energy and protein intakes on NDD were 34% and 20% less, respectively, than the K/DOQI recommendations, and 37% and 25% less on DD. Previous studies have also shown that calorie intake rather than protein deficits are more prevalent in people receiving maintenance dialysis.14 Third, certain subgroups of participants were identified whose DEI and DPI were even further reduced on DD, including women, older participants, blacks, those with diabetes, those with severe comorbid diseases, and those on dialysis for fewer than 2 years. In contrast, men, younger individuals, those without diabetes, and those on dialysis for more than 5 years consumed energy and protein intakes that approached the K/DOQI recommendations and the study’s SOC. Fourth, in multivariable analyses, age, sex, and diabetes status were shown to be independently associated with intakes, whereas black race, ICED score, and duration of dialysis were not. None of the subgroup effects were independently associated with differences between DD and NDD intakes. Fifth, this study showed the utility of the ADAT in that as selfreported appetite decreased, DEI and DPI also decreased on DD independently of other factors commonly examined for associations with nutritional indices. Wright et al15 showed similar conclusions using an electronic appetite rating system to define appetite patterns, and a 3-day diet record to estimate DEI and DPI on the same days as the electronic appetite rating system recording. In comparing a small group (n ⫽ 46) of hemodialysis patients with healthy controls, Wright et al found that hunger was highly and positively correlated with the desire to eat among hemodialysis patients on NDD, but not on DD, and that the NDD patterns paralleled reports from the healthy controls. To our knowledge, this is the first study to evaluate intake differences by type of treatment day in a large cohort (n ⫽ 1,901) of maintenance hemodialysis patients, and within that cohort, in select clinical subgroups. Low dietary intakes on DD have also been reported by Sharma et al,3 although the sample size (n ⫽ 106) was much smaller than in the present study. In contrast,

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Kloppenburg et al16 did not find significant differences in DEI and DPI between DD and NDD, possibly because of the small sample size (n ⫽ 43). Underreporting error on NDD may have been greater than on DD because intakes were assessed on days the patients had dialysis. Therefore, actual differences may have been greater, although it cannot be determined with certainty. In weighing the study’s strengths, several limitations should also be considered. This study inherits the cross-sectional study problems of different selection biases. As outlined in the study’s primary results article,5 the cohort included a higher percentage of blacks (63%) than the general U.S. hemodialysis population but offered a substantial representation of the elderly, those with diabetes, and those with cardiac disease as well as other substantial comorbidities. In terms of nutrition-related exclusions, patients with serum albumin concentration ⬍2.6 g/dL (as measured by nephelometry) were excluded from randomization, which likely biased the intakes upward because patients with higher risk or poor nutritional status may have been underrepresented. On the other hand, larger patients were excluded because participants needed to achieve the higher dose goal in ⬍4.5 hours during baseline. Only 9% of patients weighed more than 90 kg, and only 3.3% weighed more than 100 kg. This study is also limited by its use of the diet diary-assisted recalls to estimate DEI and DPI for only one 2-day period. Diet recalls have known problems with underreporting,17 which may account for the relatively low overall energy and protein intakes. Whether the small variations in DEI and DPI are truly reflective of dietary intakes or would actually be larger because of systematically inaccurate recording or underrecording remains undetermined. Moreover, the single dietassisted recall during baseline limited the precision with which DEI and DPI could be estimated. The precision with which DEI and DPI can be estimated from diet recalls increases with more frequent measurements. Kloppenburg et al16 determined that a 1-day food record was sufficient to estimate DEI and DPI with a precision of 20% in only 19% and 9%, respectively, of patients studied. They concluded that food records should be maintained for at least 5 consecutive days to obtain a more reliable and precise estimate of DEI and DPI for individuals. A strength of the dietary intake data used for

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this analysis is the large sample size using data collected by trained and repeatedly certified study dietitians over several years in geographically diverse hemodialysis units. Another methodologic limitation of this study is that the type of treatment day (DD and NDD) had to be inferred retrospectively for 73% of the diet records. Theoretically mistaken inferences would result in smaller DD–NDD differences, but the 2.7% error rate found when comparing the retrospective designations with those collected on the later study forms seemed negligible.

Conclusion The dietary energy and protein intakes of patients receiving maintenance hemodialysis were lower on DD than on NDD, and also lower than the K/DOQI nutrition and HEMO SOC recommendations. The energy and protein deficit that occurred on DD is small and, therefore, would be difficult to detect clinically outside of a large trial. Therefore, the results of this study need to be confirmed (or not) in other large-scale trials with fewer limitations regarding the diet records. Nevertheless, this study suggests that clinicians should consider carefully the potential impact of dialysis treatment schedules on nutritional intake. A large percentage of participants regardless of sex, age, race, diabetes status, ICED score, or years on dialysis reported poor or very poor appetites on DD and very good or good appetites on NDD. Those receiving maintenance hemodialysis with poor appetite by self-report, especially on DD, should be monitored closely, and interventions that aid in reversing appetite status should be implemented immediately. Based on the present evidence and clinical experience, patients receiving maintenance hemodialysis should be counseled on consuming an adequate nutrient intake to minimize the effects of suboptimal energy and protein intakes— even if hunger is absent. Further research is needed to assess prospectively the predictive power of the ADAT in its ability to monitor and detect changes in appetite, dietary patterns, and eating habits with two different delivered doses of dialysis and high- and low-flux dialysis membranes, and to determine whether the differences in intake observed in this

analysis between DD and NDD over time have an affect on patient outcome. These issues will be addressed using data from the prospective clinical trial of the HEMO Study.

References 1. Ikizler TA, Hakim R: Nutrition in end-stage renal disease. Kidney Int 50:343-357, 1996 2. Locatelli F, DelVecchio L, Manzoni C: Morbidity and mortality on maintenance hemodialysis. Nephron 80:380-400, 1998 3. Sharma M, Rao M, Jacob S, et al: A dietary survey in Indian hemodialysis patients. J Ren Nutr 9:21-25, 1999 4. HEMO Study Group (Prepared by Greene T, Beck GJ, Gassman JT, et al): Design and statistical issues of the Hemodialysis (HEMO) Study. Control Clin Trials 21:502-525, 2000 5. Eknoyan G, Beck GJ, Cheung AK, et al: Effect of dialysis dose and membrane flux in maintenance hemodialysis. N Engl J Med 347:2010-2019, 2002 6. Dwyer JT, Cunniff P, Maroni BJ, et al: The Hemodialysis pilot study: Nutrition program and participant characteristics at baseline. J Ren Nutr 8:11-20, 1998 7. Leung J, Dwyer J, Miller J, et al: The role of the dietitian in a multicenter clinical trial of dialysis therapy: The Hemodialysis (HEMO) Study. J Ren Nutr 11:101-108, 2001 8. Rocco MV, Paranandi L, Burrowes JD, et al: Nutritional status in the HEMO Study cohort at baseline. Am J Kidney Dis 39:245-256, 2002 9. Frisancho AR: New standards of weight and body composition by frame size and height for assessment of nutritional status of adults and the elderly. Am J Clin Nutr 40:808-819, 1984 10. Burrowes JD, Powers SN, Cockram DB, et al: Use of an appetite and diet assessment tool in the pilot phase of a hemodialysis clinical trial: Mortality and morbidity in Hemodialysis Study. J Renal Nutr 6:299-232, 1996 11. Greenfield S, Apolone G, McNeil NJ, et al: The importance of co-existent disease in the occurrence of postoperative complications and one-year recovery in patients undergoing total hip replacement: Comorbidity and outcomes after his replacement. Medical Care 31:141-154, 1993 12. Centers for Medicare and Medicaid Services: 2001 annual report: ESRD clinical performance measurement project. Am J Kidney Dis 39(Suppl 2):S4-S98, 2002 13. National Kidney Foundation: K/DOQI Clinical Practice Guidelines for Nutrition in Chronic Renal Failure. Am J Kidney Dis 35:S1-S104, 2000 14. Lorenzo V, deBonis E, Rufino M, et al: Calorie rather than protein deficiency predominates in stable chronic hemodialysis patients. Nephrol Dial Transplant 10:1885-1889, 1995 15. Wright MJ, Woodrow G, O’Brien S, et al: A novel technique to demonstrate disturbed appetite profiles in haemodialysis patients. Nephrol Dial Transplant 16:1424-1429, 2001 16. Kloppenburg WD, Stegeman CA, Hooyschuur M, et al: Assessing dialysis adequacy and dietary intake in the individual hemodialysis patient. Kidney Int 55:1961-1969, 1999 17. Snetselaar LG, Chenard CA, Hunsicker LG, et al: Protein calculation from food diaries of adult humans underestimates values determined using a biological marker. J Nutr 125:23332340, 1995