Development of Effective Resources for Phosphate Education for Children and Families With Chronic Kidney Disease: Hearing the Patient Voice

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.