June Leung

The Role of the Dietitian in a Multicenter Clinical Trial of Dialysis Therapy: The Hemodialysis (HEMO) Study

The Hemodialysis (HEMO) Study is a randomized multicenter prospective clinical trial, supported by the National Institute of Diabetes, Digestive, and Kidney Diseases of the National Institutes of Health. The trial is designed to assess the effects of a standard versus higher dialysis dose and low versus high dialysis membrane flux on morbidity and mortality of chronic hemodialysis patients. The role of the dietitian in the HEMO Study is to support and maintain the nutritional status of randomized participants. To ensure participant safety, nutritional status is closely monitored by a variety of biochemical and participant-reported parameters. Serum albumin and equilibrated normalized protein catabolic rates are obtained monthly. Appetite assessment and dietary energy and protein intakes using a 2-day diet diary assisted recall are ascertained at baseline and on a yearly basis. Consumption of vitamins, minerals, and nutritional supplements, including oral enterals, tube feedings, and parenteral nutrition, is obtained at least once a year. In addition, anthropometry is performed at baseline and on a yearly basis. Prespecified changes in serum albumin level or body weight trigger action by the dietitian to prevent protein calorie malnutrition. The HEMO Study dietitians play a vital role in carrying out the nutrition program for the trial. The HEMO Study should provide important information about the natural history of the nutritional status of chronic hemodialysis patients and the impact of dialysis dose and dialysis membrane flux on these parameters.

Renal DETERMINE Nutrition Screening Tools for the identification and treatment of malnutrition

Nutrition screening is the first step in identifying and treating nutrition-related problems in renal patients. The Renal DETERMINE Nutrition Screening Tools help health care professionals recognize the risk factors for malnutrition in renal patients and suggest interventions to prevent, control, or ameliorate problems when they are present. The Renal DETERMINE Nutrition Awareness Checklist provides a series of questions for the health care professional to ask the renal patient to better identify nutrition problems. It can also be used with renal patients to help educate and increase awareness of nutrition issues. The Renal DETERMINE Nutrition Screening Reference Sheets are then used to help the health care professional identify appropriate interventions for the nutrition problem. The Reference Sheets list the most common nutrition-related concerns for chronic renal insufficiency, hemodialysis, peritoneal dialysis, and post kidney transplant patients. For each risk factor, rationales are presented and interventions to resolve the nutrition related problems are provided.

Folic Acid Supplementation and Cardiac and Stroke Mortality among Hemodialysis Patients

OBJECTIVE We sought to assess whether the use of folic acid vitamin supplements reduced cardiac and stroke mortality in hemodialysis patients. Further, we examined whether the consumption of folic acid from vitamin supplements >1000 microg compared with the standard 1000 microg, and 1000 microg compared with either a lower dose or no consumption, were associated with reduced cardiac and stroke mortality risk. DESIGN We performed a secondary analysis of data from the Hemodialysis Study, a randomized clinical trial examining dialysis treatment regimens over a 3-year follow-up. PARTICIPANTS Participants included 1846 hemodialysis patients previously participating in the Hemodialysis Study. INTERVENTIONS There were no interventions. MAIN OUTCOME MEASURE Cardiac and stroke mortality were our main outcome measures. RESULTS Based on time-dependent Cox proportional hazard regression models, folic acid consumption from vitamin supplements, above or below the standard 1000-microg dose, was not associated with a decrease or increase in cardiac mortality (P = .53, above vs. standard dose; P = .46, below vs. standard dose). There was also no association between folic acid consumption and mortality from stroke (P = .27, above vs. standard dose; P = .64, below vs. standard dose). CONCLUSION The consumption of higher than the standard 1000-microg prescribed dose of folic acid was not beneficial in reducing cardiac or stroke mortality in hemodialysis patients. Similarly, the consumption of less than the standard dose was not associated with an increase in either cardiac or stroke mortality.

Association Between Adherence to Folic Acid Supplements and Serum Folate, and Plasma Homocysteine Among Hemodialysis Patients

OBJECTIVE To examine the relationship between adherence to prescribed folic acid supplements and folic acid intake, serum folate and plasma homocysteine in hemodialysis patients. The effects of change in adherence patterns from enrollment to 1 year later on changes in these same measures were also assessed. DESIGN Secondary data analysis. PARTICIPANTS Eighty-six hemodialysis patients who participated in the Hemodialysis (HEMO) Studys Homocysteine ancillary study. MAIN OUTCOME MEASURES Folic acid supplement intake, serum folate, and plasma homocysteine. RESULTS Eighty-eight percent of patients at enrollment and 91% 1 year later were adherent to prescribed folic acid supplements. Nonadherers had lower intakes of folic acid at both enrollment and 1 year later and lower serum folate levels at enrollment. Percent change was significantly different between the 3 adherence change groups for folic acid intake (P = .001) and plasma homocysteine (P < .001) from enrollment to 1 year later. The nonadherent group at enrollment had the lowest intakes and serum folate levels, and the highest plasma homocysteine levels. When they became adherent 1 year later, they had the greatest change in folic acid intake (5,461%; P = .03), coupled with a 69% increase in serum folate (P = .04) and a 29% decrease in plasma homocysteine (P = .03). CONCLUSIONS Hemodialysis patients who were nonadherent to folic acid supplement prescriptions had low folic acid intakes, low serum folates, and high homocysteine levels. When their adherence improved, folic acid intakes rose, serum folates increased, and plasma homocysteine levels decreased, although mild hyperhomocysteinemia persisted.

Imputation Methods for Handling Missing Dietary Supplement Dosage Data

In studies involving dietary supplements, when use is indicated, missing data on dosage and frequency of use are common, making it more difficult to demonstrate associations between supplements and health outcomes. Furthermore, the contribution of supplements to nutrient intakes is often considerable, and so missing data distorts not only estimates of supplements but also of total nutrient intake. If individuals with missing dietary supplement dosage data are dropped, total nutrient intakes may be seriously underestimated or biased. Also, when data are missing, sample size is reduced and the efficiency of the data analyses decline. Therefore, it is imperative that missing doses be accounted for appropriately. Imputation is a valuable technique for handling missing values that, if done appropriately, reduces bias and improves the robustness and power of statistical analyses. Developing the appropriate imputation technique is an exercise involving the examination of the dataset, assessment of the missing data (whether data is missing at random or not), stating the appropriate assumptions, using the techniques properly, and retaining clinical relevance in the process. Remedies for missing data such as adopting a single default may be insufficient. More elaborate imputation strategies must be considered that employ a variety of techniques, and then the dataset with the imputed values is analyzed. Imputation is helpful, but this always involves risks and costs. This letter reviews some of the special challenges and considerations in using imputation in dietary supplement studies. This letter refers to the paper by Leung et al entitled ‘‘Folic Acid Supplementation and Cardiac and Stroke Mortality