The role of diet and physical activity in the treatment of families with familial hypercholesterolaemia

Abstract

Background: Familial hypercholesterolaemia (FH) is a genetic disorder characterised
by elevated low-density lipoprotein cholesterol (LDL-C) levels and increased risk of
cardiovascular disease (CVD). Clinical guidelines advocate dietary and physical
activity recommendations adjuvant to life-long pharmacological treatment. However,
there is a lack of evidence to support the effectiveness of diet and physical activity in
the treatment of FH.
Aim: The aim of this thesis was to develop and evaluate an intervention targeting the
dietary and physical activity behaviours of children and their parent who are affected
by FH. Following the Medical Research Council guidance for the development and
evaluation of complex interventions, this was addressed through four studies.
Methods and results: Study one summarised the existing evidence base for the role
of diet and physical activity in the treatment of FH. Study two synthesised the
qualitative evidence regarding the experiences and beliefs of individuals with FH and
identified several enablers and barriers to treatment adherence. This informed
suggestions for clinical practice that could facilitate optimal treatment adherence. In
study three, a theoretical framework was applied to the findings of study two to
develop an intervention targeting dietary and physical activity behaviours of
individuals with FH. Twenty-six behaviour change techniques were identified for
inclusion in the intervention to target the theoretical constructs identified to influence
behaviour. Study four was a randomised, controlled feasibility trial (n=21 families)
that found it is feasible to recruit, randomise and retain families with FH and to
implement and evaluate the intervention designed in study two. The results also
provide evidence that the intervention may be associated with improvements in CVD
risk factors, including LDL-C.
Conclusion: The intervention development and evaluation undertaken for this thesis
has provided the evidence required ahead of conducting a definitive randomised
controlled trial (RCT). This RCT will be adequately powered to evaluate the potential
effectiveness of diet and physical activity treatment recommendations on LDL-C
treatment goals and CVD risk amongst individuals with FH.

Date of Award	26 Nov 2020
Original language	English
Awarding Institution	University of Bristol
Supervisor	Fiona E Lithander (Supervisor), Julian P Hamilton-Shield (Supervisor), Aidan Searle (Supervisor), Graham R Bayly (Supervisor) & David J Stensel (Supervisor)