Demographic and Psychosocial Influences on Treatment Adherence for Children and Adolescents with PKU: A Systematic Review

  • Emma Medford
  • Dougal Julian Hare
  • Anja Wittkowski
Research Report
Part of the JIMD Reports book series (JIMD, volume 39)


Phenylketonuria (PKU) is a rare genetic disorder in which the amino acid phenylalanine cannot be sufficiently metabolised. Although a build-up of phenylalanine causes irreversible cognitive impairment, this can be prevented through a strict, lifelong diet restricted in natural protein. Despite the severe consequences of poor metabolic control, many children and adolescents have phenylalanine levels above their recommended limits. This systematic review was the first to examine studies reporting demographic and/or psychosocial influences on blood phenylalanine levels, with the aim to identify factors that were robustly linked with metabolic control. Four electronic databases were searched, yielding 1,808 articles. Articles were included if they reported a statistical examination of the association between one or more demographic or psychosocial factor(s) and metabolic control (as measured by blood phenylalanine concentration) for children and adolescents with PKU. Twenty-nine studies were selected for inclusion, which examined a range of child, parent and family factors related to blood phenylalanine levels. The most reproducible association was with child age, with metabolic control worsening with increasing age. This suggests that interventions promoting treatment adherence would be particularly beneficial for adolescents. There was a paucity of studies in some areas, and the quality of included studies varied; therefore, the conclusions of this review are preliminary. Research recommendations focus on promoting the growth of the evidence-base to support clinical practice.


Adherence Children Demographic Metabolic Phenylketonuria Psychosocial 



We would like to express our sincere gratitude to Katie Carpenter for her assistance with this literature review.

Supplementary material

978-3-662-57577-2_52_MOESM1_ESM.docx (99 kb)
Supplementary Table 1 Methodological characteristics of included studies and factors examined for association with treatment adherence (DOCX 33 kb)
978-3-662-57577-2_52_MOESM2_ESM.docx (99 kb)
Supplementary Table 2 Overview of QATSDD item scores per study (DOCX 42 kb)
978-3-662-57577-2_52_MOESM3_ESM.docx (99 kb)
Supplementary Table 3 Study findings separated by child, parent and other family factors (DOCX 55 kb)


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Copyright information

© Society for the Study of Inborn Errors of Metabolism (SSIEM) 2017

Authors and Affiliations

  • Emma Medford
    • 1
    • 2
  • Dougal Julian Hare
    • 3
  • Anja Wittkowski
    • 1
    • 2
  1. 1.School of Health SciencesUniversity of ManchesterManchesterUK
  2. 2.Greater Manchester Mental Health NHS Foundation TrustManchesterUK
  3. 3.School of PsychologyCardiff UniversityCardiffUK

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