Treatment Adherence in Type 1 Hereditary Tyrosinaemia (HT1): A Mixed-Method Investigation into the Beliefs, Attitudes and Behaviour of Adolescent Patients, Their Families and Their Health-Care Team

Abstract

Background: Type 1 hereditary tyrosinaemia (HT1) is a rare metabolic disorder caused by an enzymatic defect in the metabolism of the amino acid tyrosine. Primary treatment for HT1 is nitisinone (Orfadin) in conjunction with a low-tyrosine/phenylalanine diet. The appropriate use of nitisinone medication and adhering to specialist diet is thus central to the successful management of HT1.

Objective: To date, no published research has examined adherence (to medication and diet) and factors that influence it in the context of HT1. This study aimed to ascertain the extent to which non-adherence is a problem in this patient population, identify perceived barriers and facilitators to treatment adherence and explore the role of illness beliefs and treatment perceptions in treatment management.

Methods: The present study used a combination of qualitative interviews and quantitative survey methods with patients, carers and health-care professionals (HCPs).

Results: This study found adherence to medication to be high amongst patients with HT1 and their carers who administer it. However, adherence to diet was reported to be much lower. A key factor influencing adherence to diet was age, with adolescents reported to have most difficulty adhering.

Conclusions: The results indicate that adherence to dietary instructions becomes more problematic as children with HT1 grow older. Greater involvement in managing their condition and in their consultation at an early stage may have a positive impact on future adherence by increasing their investment and understanding of the treatment regime, potentially making adherence rates more stable and less influenced by moving through different life stages.

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Competing interests: None declared

Appendices

Disclaimer

The views expressed in this article are those of the authors and do not represent an official position of the institution or funders associated. The work represented in this article was carried out independently from the funding source.

Source of Support

This work was conducted with funding from Sobi, Swedish Orphan Biovitrum AB, Stockholm.

Take-Home Message

Patients with HT1 and their carers need greater support adhering to the low tyrosine/phenylalanine diet necessary for successful management of this condition, through education and increased involvement in consultations.

Compliance with Ethics Guidelines

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• Absence of previous similar or simultaneous publications.

• That all authors have inspected and approved the manuscript.

• That all authors have made a substantial contribution to the work (all authors should have been involved in (a) conception and design, or analysis and interpretation of data, and (b) drafting the article or revising it critically for important intellectual content).

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Conflict of Interest

Dr Sumaira Malik, Dr Sinead NiMhurchadha, Dr Christina Jackson and Dr Lina Eliasson PhD are all employed by Atlantis Healthcare, which received funds from Swedish Orphan Biovitrum AB to carry out this project.

Professor John Weinman has received consulting fees from Swedish Orphan Biovitrum AB, to carry out this project and attend scientific meetings.

Dr Sandrine Roche has received Professor Weinman is also a part time employee of Atlantis Healthcare. Support from Swedish Orphan Biovitrum AB, to attend scientific meetings and to carry out data collection for this study in France.

Professor John H. Walter has received support from Swedish Orphan Biovitrum AB, to attend scientific meetings.

Informed Consent

All procedures followed were in accordance with the ethical standards of the responsible committee on human experimentation (institutional and national) and with the Helsinki Declaration of 1975, as revised in 2000 (5). Informed consent was obtained from all patients prior to inclusion in the study.

Details of the contributions of individual authors:

SM: study conception and design, data collection, analysis and interpretation and drafting of the manuscript. SNM: data collection, analysis and interpretation and drafting of the manuscript. CJ and LE: data interpretation and critical revision of the manuscript. Prof JW: study conception and design and critical revision of the manuscript. SR: data collection and critical revision of the manuscript. JW: data collection and critical revision of the manuscript. All authors gave final approval of the version to be published.