Effect of Access to Dietary Intervention in a Dialysis Unit

Objective:

The aim of this study is to explore the effect of access to individual dietary counselling by a dietitian in the dialysis unit on biochemical values (phosphorus and potassium), diet, nutritional status, quality of life (QoL) and health literacy (HL).

Research question:

What is the effect of access to dietary treatment in people receiving dialysis treatment on biochemical values (phosphorus and potassium), diet, nutritional status, quality of life and health literacy? Hypothesis: Having access to a dietitian can better laboratory values and affect dietary intake, nutritional status, QoL and HL in a positive matter.

Method:

Pilot cluster RCT study in the dialysis units in Holbæk and Slagelse in Region Zealand, Denmark. Clustering of people on dialysis the same day to either intervention or control group. The groups is expected to be similar regarding clinical characteristics. A pilot project will be conducted in 2024 in the dialysis units in Slagelse and Holbæk.

Data collection:

Both groups:

• Patient characteristics (at the beginning of project): Age and gender, height, medical diagnosis, socioeconomic data (income, job, education, partner status) and dialysis vintage.
• Clinical Data (before and after the intervention, and at 6 and 12 month after the intervention period): Biochemical values (phosphate, potassium, urea, albumin, PTH), anthropometric measures (dry weight, actual weight), medication, ultrafiltration, and number of contacts with dietitian.
• Questionnaires and tests (collected before and after the intervention): Body composition (fat, fat-free mass, water), Nutritional status, Intake (HeartDiet Questionnaire), Quality of Life (KDQOL-SF), Health Literacy (HLQ), and previous dietary treatment.

Primary outcome: Change in average p-phosphate Secondary outcomes: Change in average p-potassium, number of phosphate binders, number of potassium binders, HeartDiet-score, Nutritional Status (nutritional screening), Adherence to diet (End Stage Renal Disease Adherence Questionnaire, ESRD-AQ-score), Quality of life (Kidney Disease Quality of Life Short Form, KDQOL-SF-score) and Health literacy (Health Literacy Questionnaire, HLQ-score)

Intervention:

The intervention group receives an initial individual dietary interview, monthly follow-up and weekly access to a dietitian in the dialysis unit for four months.

The individualized dietary treatment based on the patient's preferences and needs according to the Nutrition Care Process. It is carried out according to the practical guidelines from the Danish Dietetic Association on dietary treatment of chronic kidney disease. The dietary treatment uses a dialogic and person-centered approach The intervention is described in the protocol using the TIDieR framework. The control group receives usual care with referral to a dietitian when needed.

Statistics:

The average phosphorus level and standard deviation after a diet intervention was 1.58 ± 0.32 mmol/l, therefore using 0.32 mmol/l in calculation of sample size. An implementation of guidelines and a systematic review showed a difference in phosphosus levels between intervention and control group of 0.23 and 0.30 mmol/l respectively.

Calculation of sample size using "Sample Size Calculator (clincalc.com)". Using the values mentioned above, a power of 80% and a significance of 5% shows a sample size of 18-30 people in each group to show a significant change in phosphorus levels.

Comparison of changes in average values using unpaired t-test, including endpoints of p-phosphorous and p-potassium, QoL-score and health literacy score. For dichotomous endpoints such as nutritional score, comparison of the percentage of the groups within and without specific limits. Data analysis with intention-to-treat and statistical calculations by a person not familiar with the groups.