The reality of dietary compliance in the management of phenylketonuria

Abstract

In phenylketonuria (PKU), it is common for blood phenylalanine (Phe) concentrations to be outside optimal target ranges, particularly in teenagers and adults, indicating inadequate compliance. It is well known that significant noncompliance exists, and the situation in PKU would appear no different than other chronic conditions. In PKU, compliance is complex, being subject to diverse definitions, and factors influencing compliance include the nature and nurture of the patient, as well as the inconvenience, cost and availability of dietary treatment. It is also a dynamic process, with many patients changing between a state of compliance and partial and noncompliance. In PKU, compliance has received little rigorous study, and there have been few observational reports identifying barriers and behaviors impacting dietary compliance. Compliance assessment measures remain inadequately defined. The direct assessment of blood Phe concentration is perhaps the best overall measure, but there is no universal agreement about the number of Phe concentrations that should be within target range and frequency or timing of measurement. Although no one strategy for improving compliance is universally effective, and an individualized approach to noncompliance is essential, it is important to have clear evidence about the most effective strategies in achieving long-term dietary adherence in PKU.

Nutritional Changes and Micronutrient Supply in Patients with Phenylketonuria Under Therapy with Tetrahydrobiopterin (BH4)

“…Moreover, the AAM have an unpleasant taste. As a consequence patients often show a low diet adherence, particularly older children and adolescents (Macdonald 2000;Macdonald et al 2010). Especially during adolescence many patients drop out of specialized care (M€ utze et al 2011).…”

Treatment Adherence and Psychological Wellbeing in Maternal Carers of Children with Phenylketonuria (PKU)

“…When examining predictors of the proportion of blood phe concentrations within target range (Table 4), child age was entered first, given previously reported associations with metabolic control (MacDonald et al 2010). Parental age was not selected as a predictor variable given the high correlation with child age (r ¼ 0.73), and perceived support from family was used rather than total social support score given the stronger correlation with percentage of blood phe concentrations in target range.…”

Successful Live Birth following Preimplantation Genetic Diagnosis for Phenylketonuria in Day 3 Embryos by Specific Mutation Analysis and Elective Single Embryo Transfer

“…This correspondence outlined the adverse effects of PKU on the quality of life of patients and their caregivers, especially in childhood when a strict diet is required until the age of 10 years, and in adolescence when the diet compliance proves to be more difficult. In adulthood, self-management of the condition becomes quite challenging and poses great difficulties both psychologically and socially (Feillet et al 2010a;Macdonald et al 2010). The cost, inconvenience, and sometimes difficult access to PKU diet increase the difficulty of adhering to it.…”

“…The cost, inconvenience, and sometimes difficult access to PKU diet increase the difficulty of adhering to it. Although there is still debate over whether adult PKU patients need a strict phenylalanine-restricted diet and despite the fact that there are some adults with PKU who do not follow a restricted diet and lead normal lives, many studies have advocated following a restricted diet in adulthood as it has been shown that high phenylalanine levels in adults can have adverse effects on mood, sustained attention, concentration, and cognitive ability (Feillet et al 2010b;Ten Hoedt et al 2011;Macdonald et al 2010;Moyle et al 2007;Simon et al 2008). Restricted diet is also crucial in female adults with PKU planning for a pregnancy, as maternal PKU has been shown to cause fetal abnormalities including microcephaly, congenital heart disease, and mental retardation (Prick et al 2012).…”

“…In addition to a diet low in phenylalanine which is present in all protein-rich foods, dietary supplementation, such as protein-free formulas and protein substitutes, is also required in combination with the diet (Feillet et al 2010b;Macdonald et al 2010). Other non-traditional therapies are also being used such as large neutral amino acids (LNAA) which have shown to be beneficial in maintaining low phenylalanine levels in the body without the need of dietary control ) and other therapies that are still under experimentation such as gene therapy, enzyme replacement therapy and cell transplantation (Mitchell et al 2011;van Spronsen and Enns 2010).…”