Nutrition’s role in the management of chronic pain

Chronic pain is a debilitating condition which affects 20% of adults or more worldwide. These individuals live with pain on a daily basis which affects their ability to work and socialise. Chronic pain also impacts an individual’s mood, movement and the foods and drinks that they consume. Chronic pain has important implications for long-term health and risk and severity of chronic diseases. Given the complexity of chronic pain, current treatment focuses on the whole-person with the approach often involving a multidisciplinary team of clinicians, including pain specialists, nurses, psychologists, psychiatrists and pain physiotherapists. These clinicians provide education about the whole-person approach and active strategies for patients to utilise to help manage their pain. The whole-person approach comprises the biopsychosocial and lifestyle factors which modulate the pain experience. Traditionally nutrition has been underrepresented as a component of pain management, despite associations between chronic pain and elevated weight status, increased risk of chronic diseases and sub-optimal dietary intake and overall poor diet quality. Given the association demonstrated in previous research suggesting a relationship between chronic pain and poor diet-related health, and the current lack of nutrition support for people within clinical services experiencing chronic pain there is a need to explore the role of nutrition in the management of pain. This thesis presents five individual studies which work synergistically to address the gap in the current evidence base on nutrition in pain management and to answer the overall research question: How can people experiencing chronic pain use nutrition to manage their pain experiences? To my knowledge, this thesis is the first body of work to comprehensively explore the role of nutrition in pain management using a collaborative approach involving both quantitative and qualitative research. The body of work presented in this thesis involves a collaboration between dietetic researchers from the University of Newcastle and clinicians from Hunter Integrated Pain Service (HIPS), a tertiary pain service in Newcastle, New South Wales. The primary aim of this thesis is to generate new evidence to address gaps in the literature exploring the role of dietary intake and nutrition in the management of chronic pain. The second aim is to develop, implement and assess the effectiveness of a personalised dietary intervention at HIPS. The thesis also presents six secondary aims which are addressed in the five studies and are presented in the following order: Secondary aim 1: Systematically review nutrition interventions for chronic non-cancer pain. A systemic review was conducted to investigate the impact of nutrition interventions on participant self-reported pain severity and intensity in people with chronic pain or a chronic pain related condition. In total 71 studies were identified which were categorised by their intervention: altered overall dietary intake (n=16), altered a single nutrient (n=5), prescribed a nutrition supplement (n=46) or prescribed fasting therapy (n=4). Of these studies, 23 were eligible for meta-analysis. Findings from the meta-analysis showed that, when combined, all nutrition interventions had a significant effect on pain reduction. Those studies which altered overall dietary intake or a single nutrient had the greatest effect. Secondary aim 2: Describe weight status, comorbidities and patient treatment goals of patients attending a pain service. A cross-sectional study was undertaken using data from patients who attended the HIPS between July – December 2014. Data were collected from the Electronic Persistent Pain Outcomes Collaboration (ePPOC) referral questionnaire and the Pain Assessment and Recovery Plan (PARP), both tools are used as part of the standard care provided at HIPS. One-hundred and sixty six patients completed the ePPOC referral questionnaire and 153 patients completed the PARP. Body Mass Index was calculated using self-reported weight and height. The average BMI was 31.7 kg/m² (ranged from 18.52-54.46 kg/m²). Thirty-three percent of patients were in the overweight BMI category and 45% were in the obese category. Eighty-seven percent of females and 77% males reported a waist circumference that placed them (≥ 80 cm and ≥ 94 cm, respectively) at risk for developing chronic disease. Of the comorbidities patients could choose from the top two answers were osteoarthritis/degenerative arthritis (25%) and depression/anxiety (22%). Nearly two thirds of the patients (64%) reported having ≥ 2 comorbidities. Patients listed and prioritised treatment goals when completing the PARP. In descending order of frequency participants chose the following areas from the whole-person approach to focus on as part of their recovery plan: physical activity, nutrition, connection, mindbody and biomedical. Secondary aim 3: Identify nutrition-related goals reported by patients at this service. Using the same cross-sectional study outlined above the patients nutrition-related treatment goals were further categorised with 47% choosing a specific nutrition-related goal (e.g. reduce soft drink intake or increase vegetable consumption), 27% of patients stating that they wanted to improve their overall diet and 27% of patients stated that they wanted to lose weight or reduce their waist circumference. Secondary aim 4: Collect and collate opinions of staff employed at two pain services about incorporating nutrition into practice. Qualitative focus groups (n=3) were held with staff (n=13) from HIPS and Tamworth Integrated Pain Service in order to gather the opinions of staff regarding the integration of nutrition support into current practice. Staff from all disciplines attended including: nurses, administrative staff, psychologists, physiotherapists and one pain specialist. On average, staff had been working in their respective fields for 18.4±12.8 years and specialising in chronic pain for 6.5±6.6 years. Staff discussed the benefits of nutrition intervention acknowledging patients would receive an increase in knowledge and skills and the service would gain a more comprehensive whole-person approach to pain management. Key barriers which would impact patients included comfort eating, lack of motivation and access to dietetic services. Key barriers for the service included time limitations and access to dietetic services. Preferences for intervention content were: evidence-based, simple education and skill development with practical strategies and visual incentives, with a focus on nutritional benefits for pain experiences, not weight management. The overall preferred intervention delivery method was a flexible combination of face-to-face and technology-based resources with the intervention ideally developed and/or delivered by an Accredited Practicing Dietitian. Secondary aim 5: Explore attitudes and beliefs of patients in relation to the role of nutrition in pain management. Qualitative focus groups (n=5) were also held with patients (n=21) from HIPS in order to explore the opinions of patients regarding the integration of nutrition support into current practice. Patients were asked how they perceived the meaning of ‘healthy eating’ with most participants identifying fruits and vegetables as the main component of healthy eating. Patients also discussed how accessing and preparing food can lead to an exacerbation of pain and therefore many patients rely on convenience foods. Medication and mental health issues were also identified as contributing to the difficulty of maintaining a healthy weight. Patients identified that the main benefits of participating in a nutrition intervention would be improved overall health, increased knowledge, skills and self-efficacy. The significant barrier which most patients discussed was the cost of food and health care in general. The ideal intervention from a patient perspective, would include easy and practical ideas which are delivered using a combination of in-person and technology components to enhance flexibility. There were mixed responses with regard to patients’ use and confidence about using technology with some patients promoting the use and others preferring in-person. Secondary aim 6: Investigate the effectiveness of a personalised dietary intervention and dietary supplement in patients attending a pain service. The final study in this thesis explores the efficacy of a six-week 2x2 dietary intervention study on pain scores, quality of life and dietary intake of patients attending HIPS. This intervention was informed by the results of all previous studies to increase the acceptability and success of the intervention. Two intervention components were tested and these included personalised dietary consultations provided using telehealth and a dietary supplement, a fruit juice high in antioxidants (active fruit juice). Sixty participants were randomised into four groups with each group receiving either the personalised dietary consultations or waitlist control and the active fruit juice or placebo fruit juice. Forty-two participants completed the study and results showed one groupby-time effect where the group receiving the personalised dietary consultations and active fruit juice had a significant reduction in percentage energy from total fat (p=0.024). Other results demonstrated that overall, all groups had a statistically significant improvement in the following pain scores: pain interference (-0.9±0.3 points, p=0.003), pain self-efficacy (+6.2±2.2 points, p=0.004) and pain catastrophising (-3.8±1.8 points, p=0.046). There were also statistically significant improvements for all groups in six of the eight quality of life categories post intervention and for the percentage energy coming from nutrient-dense foods (+5.2±1.4%, p<0.001). [More details in thesis abstract].