Assessment of Protein Intake Using 2 Types of Nutritional Collection in Comparison with 24-hour Urine Urea, in Chronic Kidney Disease.

In France, 10% of the population suffers from chronic kidney disease (CKD). CKD is classified into five stages, described from the least severe (stage 1) to the most severe (stage 5). Every year, in the PACA region, around 1,000 new patients present with end-stage CKD (5D), necessitating the introduction of suppletive therapy, whether hemodialysis, peritoneal dialysis or kidney transplantation. In CKD stages 4 and 5, a hypo-protein diet can be proposed to delay dialysis initiation (Garneata et al. 2016).

To introduce a low-protein diet, the dietician first assesses protein intake. This can be done by :

• Measuring 24-hour urine urea. This is the reference method for assessing the amount of protein consumed over the last 24 hours. However, it cannot be used to determine the patient's dietary habits, and therefore cannot be used to suggest modifications with a view to introducing a low-protein diet.
• A detailed dietary record. The 3-day dietary record currently in use (a tool for recording dietary habits defined by the HAS) provides a reliable assessment of protein intake. However, this tool takes up a lot of dietetic time, limiting the time available for nutrition education and the number of patients who can benefit from a dietetic consultation.

MS-Nutrition is a start-up that has developed a web application that can be used by patients themselves to assess nutritional intakes, incorporating a food frequency questionnaire (known as the FFQ questionnaire) used to obtain information on the frequency of foods and drinks consumed over a period of time (1 week, 1 month...).

For the general population (without CKD), there is good agreement between the FFQ questionnaire and a conventional ingesta assessment (3-day dietary record as currently practiced or 24h recall, another collection based on the previous day's consumption) (Affret et al., 2018; Deschamps et al., 2009). These studies on healthy adults do not take into account the reference method (urinary urea) for assessing protein intake.

Only one study in the CKD population evaluates the concordance of the assessment of protein intakes (as well as calcium, phosphorus, potassium and sodium intakes) between an FFQ questionnaire and a dietary record (24-hour recall) (Affret et al. 2017). This study shows an acceptable correlation between the FFQ and the dietary record (correlation coefficient between 0.05 and 0.79, with a median of 0.40), yet this study was carried out without dietary intervention and using a different type of dietary record. As in studies on a population of healthy adults, protein intakes assessed by any type of dietary questionnaire are not compared with a more reliable assessment of these same intakes (24-hour urine urea).

The proposed study will compare the concordance of dietary intake assessment between each of the 2 types of dietary collection (FFQ and a 3-day dietary collection) and 24-hour urine urea, which limits the biases inherent in dietary collection.