- Title
- The role of diet in recurrent stroke risk
- Creator
- Zacharia, Karly
- Relation
- University of Newcastle Research Higher Degree Thesis
- Resource Type
- thesis
- Date
- 2024
- Description
- Research Doctorate - Doctor of Philosophy (PhD)
- Description
- Despite recurrent stroke being largely preventable, global rates remain high. Medical management alone is insufficient to reduce this risk. The risk factors for stroke can be modified by changes in lifestyle (diet and physical activity). Hypertension is the risk factor with the highest population-attributable risk, meaning that it can be modified. Poor diet quality is also an important risk factor. There is evidence for the role of diet in preventing primary stroke, and the risk factors for primary stroke mirror those of recurrent stroke. It may be assumed that a better diet will also mitigate recurrent stroke risk; however, there is little evidence from randomised controlled trials to support this. Further, little is known about the diet quality of stroke survivors outside the acute setting or the barriers and facilitators to stroke survivors achieving a healthy diet. Preliminary evidence suggests that an improved diet quality combined with behaviour-change support may reduce recurrent stroke risk. The Mediterranean dietary pattern shows the greatest potential for effect. The Mediterranean diet is a plant-based dietary pattern characterised by a high intake of fruits, vegetables, whole grains, nuts, seeds, fish in moderate amounts and olive oil as the main culinary fat. It is also characterised by a low intake of energy-dense, nutrient-poor foods. However, there is little evidence from randomised controlled trials to quantify this and, therefore, no standardised clinical guidance for interventions. This thesis presents a series of five studies to address the gap in the evidence base. Overall, these studies shed light on the role of diet in recurrent stroke risk. This thesis aims to answer these overarching questions: 1. What are the dietary intake and diet quality of community-dwelling Australian stroke survivors? 2. What are the barriers and facilitators for performing dietary behaviours (accessing, planning for, shopping for and preparing foods) after stroke? 3. Can we co-design a Mediterranean diet program using an Integrated Knowledge Translation framework that can be delivered via telehealth for stroke survivors? 4. Is this diet program feasible, and does it have preliminary efficacy? 5. Can this diet program be delivered in a larger, fully powered trial? Methods To answer the research questions above, five studies were undertaken, including two cross sectional studies, an intervention co-design study, a pilot trial and a process evaluation. Study 1: We conducted a cross-sectional study to assess the diet quality of 89 community dwelling Australian adult stroke survivors, using the Australian Eating Survey Food Frequency Questionnaire. Study 2: We asked participants (n = 52) to complete the Food Choices after Stroke survey,designed to understand how stroke outcomes affect dietary behaviours, supports accessed and future support preferences. We then conducted in-depth individual interviews (n = 8) and analysed the data thematically for a deeper understanding. Study 3: We had a research team, including stroke survivors and disability-specialist dietitians, co-design a complex intervention aimed at reducing stroke risk factors by improving diet quality, using an Integrated Knowledge Translation approach. This process involved four iterative workshop phases, two of which involved people with lived experience of stroke and their carers. Study 4: We piloted the dietary intervention alongside a physical activity intervention developed using the same method as part of a four-arm, randomised, assessor-blinded pilot trial (ENAbLE-pilot), which answered Research Question 4. Participants were three months to 10 years post-stroke and took part in a six-month intervention. Outcomes were feasibility measures, blood pressure, diet quality, Mediterranean diet score and quality-of-life measures. Study 5: We conducted a process evaluation of the pilot trial using the RE-AIM (reach, effectiveness, adoption, implementation, maintenance) framework to answer Research Question 5. Mixed methods were used to evaluate the reach, effect, adoption, implementation and maintenance of the pilot trial and to assess whether it can be delivered in a fully powered trial. Results Study 1: We found overall diet quality to be low, with one-third of stroke survivors having a mean Australian Recommended Food Score of 19.8 (± 7.3), which is very poor. Those who lived alone had a poorer diet quality than those who did not. Stroke survivors had a high consumption of non-core (energy-dense, nutrient-poor) foods and fats and a low intake of potassium and fibre, suggesting a reliance on convenience foods. Few met the recommended daily intake of nutrients important in stroke risk. The percentages of people meeting the recommended daily intake were 2% for dietary fibre, 15% for potassium and 18% for omega-3 fatty acids. The lack of these nutrients in the diet also suggests that stroke survivors are not adhering to a Mediterranean dietary pattern. Study 2: We found that stroke outcomes affected most survivors’ ability to perform dietary behaviours such as planning, shopping, and meal preparation (96%). Fatigue was the most common barrier (72%, n = 36). Only 45% had access to support for dietary behaviours, mostly from family members or carers. Very few participants reported accessing dietetic support post-acute care. Both the survey and interview participants reported using adaptive equipment and compensatory strategies to support dietary behaviours. Future support needs to be online, accessible and delivered in a variety of ways; involve a dietitian; and be tailored to the needs of the individual. Study 3: We co-designed an intervention to reduce stroke recurrence aimed at improving diet quality and adherence to a Mediterranean dietary pattern after stroke. Persona and journey mapping strategies co-opted from marketing user-experience methods were used to engage participants in the co-design process. The result was a rigorously co-designed intervention mapped to the Template for Intervention Description and Replication (TIDieR) checklist and specific to the needs of stroke survivors. Study 4: We piloted our Mediterranean diet intervention as part of the four-arm ENAbLE pilot randomised trial. The trial was found to be feasible, with 40 participants randomised over 23 months. There was a 90% completion rate and high intervention fidelity. Adverse events were frequent but generally unrelated to the intervention. ENAbLE-pilot was not powered for effect; however, there were improvements in stroke risk indicators (lower blood pressure, higher diet quality and Mediterranean diet score) for participants receiving the dietary intervention, indicating the potential for efficacy. Study 5: We used the RE-AIM framework and determined the reach, effectiveness, adoption, implementation and maintenance of the ENAbLE-pilot trial. Reach: the recruitment process was effective; however, the participants were younger and could walk more independently than the broader Australian stroke survivor population and did not have aphasia. Effectiveness: the intervention showed preliminary efficacy for most outcomes. Adoption: completion and acceptability were high. Implementation: intervention fidelity was high, with a substantial frequency and variety of behaviour-change techniques used throughout the intervention. Maintenance: there was attrition at the 12-month follow-up, but efficacy was mostly maintained. The results support moving forward with a fully powered clinical trial after a review of process evaluation results by the research team and a modification of the intervention program. A recognition of the role of diet in recurrent stroke has grown, but there is a lack of evidence. Our findings from these five studies have provided the first evidence for the diet quality of stroke survivors outside the acute setting. We have described the facilitators and barriers to performing dietary behaviours and co-designed an intervention to support dietary change that includes development of co-designed resources, a 6-month telehealth program based on the Mediterranean dietary pattern. Our findings from the pilot trial have identified a feasible, acceptable and preliminarily effective intervention for stroke survivors that delivered measurable dietary change. However, further research is needed to better establish the role of diet in recurrent stroke risk. This research provides value for stroke survivors, as they are not routinely offered dietetic care as part of their stroke follow-up recovery and rehabilitation process. The evidence provided shows the importance of continuing this work to improve access and support the engagement of stroke survivors with healthy eating behaviours.
- Subject
- stroke; prevention; dietary behaviours; diet; Mediterranean; pilot trial
- Identifier
- http://hdl.handle.net/1959.13/1510187
- Identifier
- uon:56354
- Rights
- Copyright 2024 Karly Zacharia
- Language
- eng
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