Improving Phosphate Control in Children With CKD

Background and Rationale

Background:

CKD mineral and bone disorder (CKD-MBD) can lead to debilitating skeletal complications, fractures, poor growth and vascular calcification, and remains one of the most challenging areas of CKD management. Serum phosphate and related measures of MBD, including Fibroblast Growth Factor 23 (FGF23) and parathyroid hormone (PTH), are raised in CKD and causally associated with adverse outcomes including vascular damage and calcification, left ventricular hypertrophy and renal bone disease. Reduction in dietary phosphate intake and regular intake of phosphate binder medications is required for optimal phosphate control but is extremely challenging, leading to poor adherence in a significant number of patients. The International Paediatric Dialysis Network Registry reports that in over 900 children on PD, 45% had high serum phosphate levels, with the prevalence of hyperphosphataemia increasing to 80% in adolescents.

Paediatric renal dietitians are responsible for educating families about dietary phosphate intake: limiting foods high in organic phosphate as well as avoiding the "hidden" inorganic phosphate from food additives, without compromising nutritional adequacy. Phosphate educational material (PEM) have been developed primarily for adults but dietary adherence is less than 50%, and is similarly low in children. Not only must children understand how to reduce their dietary phosphate intake but also how to use phosphate binder medication to reduce phosphate absorption from their foods and drinks. Adherence to binder medication is typically low due to poor palatability and the complexity of administration. Phosphate binder adherence is compounded by issues of access at school and psychological impacts, particularly during adolescence.

Educational interventions have mainly focused on the adult haemodialysis population with short-term follow-up. There are eight randomised controlled trials (RCTs) of using an educational intervention in adults with CKD or on dialysis which conclude that such interventions increased adherence compared to no intervention or routine standard care. A meta-analysis of adult RCTs also reported that educational initiatives can improve serum phosphate levels. Adult data has limited applicability to the management of hyperphosphataemia in CYP, as understanding and compliance with dietary restrictions will often be a joint responsibility between the CYP and their caregivers. There are very few studies assessing the success of educational programmes in paediatrics but, despite some showing an improvement in knowledge scores, interventions seem not to be associated with changes in serum phosphate or PTH. However, these studies had small sample sizes, were of short duration and learning patterns or factors influencing behaviour were not explored. Education strategies to balance dietary phosphate load to binder dose have been developed for children but require a high degree of patient motivation and do not account for the variable presence and bioavailability of inorganic and organic phosphate. The very high prevalence of hyperphosphataemia and its complications makes it clear that current management strategies are not effective and that alternative approaches are required to ensure optimal phosphate control.

Gaining feedback from children and their families about the challenges they face with phosphate control, as well as how they respond to dietary educational tools, is essential to enable meaningful improvements to be made to their health care. Educational psychologists report that adherence to any advice is improved when an individual's learning style (such as visual or auditory) and preferences for learning materials is provided for. Thus, although written or verbal explanations are the most common approaches, pictures and diagrams are more effective with visual learners. Similarly, adolescents report that they want more health-focused communications, presenting data as charts and graphs. In paediatric practice, the understanding of both the child and their parents must be considered and the parent-child interplay can influence the ability to learn. Sharing experiences and strategies between groups of parents and children can motivate long-term dietary changes. Healthcare professionals need to identify age-appropriate, relevant and engaging educational strategies informed by patient preferences, as these are most likely to empower, upskill and ensure optimal long-term adherence.

Rationale:

An international panel of paediatric renal dietitians and nephrologists from the Paediatric Renal Nutritional Taskforce (PRNT) have collaborated to develop a questionnaire (PUKA) to assess the baseline phosphate knowledge and understanding of CYP with CKD and their caregivers. A literature review was conducted to analyse existing instruments to evaluate phosphate knowledge. This showed that there was a lack of existing tools with proven validity and reliability that were suitable for use in paediatrics. However, this proved a useful guide for constructing a questionnaire and the questions chosen, format and design of the questionnaire was informed by those used in other studies, but expanded to gather background information on teaching preferences and problems experienced in relation to dietary changes or adherence to phosphate binder medication. This has been piloted on 10 CYP and their families to ensure face validity. The PUKA questionnaire will be completed by a purposive sample of CYP with CKD and caregivers in the 4 UK and 5 European nephrology units. The questionnaires will analysed to generate a phosphate knowledge score. Questions relating to personal opinions (such as preferred phosphate education approaches, perceived problems associated with implementing the reduced phosphate diet or taking phosphate binder medication) will be categorised and calculated as frequencies to represent the distribution of views. Correlation analysis will be used to measure the degree of association between any two variables (for example age, dialysis status, baseline biochemistry and knowledge score).

Current national and international PEM will be collated, evaluated and a representative sample selected. Focus groups of 5-6 children with CKD or caregivers will be run across these sites to gain feedback on these selected PEM and to further explore their perceived barriers and facilitators to adherence. The PUKA questionnaire and focus group data will be used to inform the development of PEM that address knowledge gaps and utilise the preferred education techniques. This novel approach will address adherence issues, empowering families to take ownership of phosphate management by personalising their child's care and offering patient choice, thereby optimising phosphate control and long-term bone and cardiovascular outcomes.

Benefits of research:

The investigators hope to find the real knowledge gaps and practical challenges experienced by CYP from diverse backgrounds, as represented across the partner sites to inform the co-design of PEM. Harnessing the expertise of an international team of dietitians and nephrologists is a unique strength of this proposal, including input from a clinical psychologist and 5 patient representatives. Patient-led resources will enable CYP to take control of their health, improve phosphate control and reduce long term adverse bone and cardiovascular outcomes. In addition, this project may also serve as a template to inform the development of future educational materials produced for children with kidney diseases.