Abstract
Background: Free sugar intake plays a major role in the development of dental caries. Therefore, proper control of free sugar intake through interventions based on a valid behaviour change framework may help in preventing dental caries among adults. The World Health Organization and Public Health England has identified the need to develop interventions to reduce free sugar intake among Adults and children (WHO, 2015; PHE, 2014).Aim: The overall aim of this PhD thesis is to examine the predictors related to reducing free sugar intake among White ethnic groups in the UK which can help in developing future interventions.
Methods: This PhD research project employs two research method designs: systematic review and a mixed method design. This thesis is divided into four studies. The first study is a systematic review of the effect of interventions based on Social Cognition Models (SCMs) on sugar intake in adults, when compared with educational interventions or no intervention. A range of papers were considered: Systematic Reviews with or without Meta Analyses; Randomised Controlled Trials; Controlled Clinical Trials and Before and After studies, of interventions based on Social Cognition Models aimed at dietary intake of sugar in adults. Sources: The Cochrane database including: Oral Health Group’s Trials Register (2015), MEDLINE (from 1966 to September 2015), EMBASE (from 1980 to September 2015), PsycINFO
(from 1966 to September 2015) were searched. On the basis result from the systematic review, the Second Study which is a qualitative study, comprising interviews with 27 individuals concerning their sugar intake, highlighting the facilitating factors and barriers to reducing sugar intake. The COM-B model and the Theoretical Domains Framework (Michie et al 2011, 2013) were used to analyse the data, within the analytical approach of Framework theory. On the basis of this analysis, the third Study was carried out to develop an online survey of Barriers to and facilitating factors for reducing sugar intakes based on the Theoretical Domains Framework. After the online survey was piloted with 20 individuals and modified, the fourth Study was carried out which is an online cross-sectional survey of 200 individuals was conducted exploring the relationship between the newly developed questionnaire measure of barriers to and facilitating factors for sugar intake, and sugar intake as recorded by a Food Frequency Questionnaire.
Results: For the systematic review, no studies were located which fulfilled the criteria of the review, highlighting the need to explore the facilitators and barriers to reducing free sugar intake among White ethic groups by using two models of Behaviour Change Wheel system which of the next study. For the qualitative study, data saturation occurred at 27 interviews. The COM-B Model and TDF domains captured various factors that may influence the consumption of free sugar. TDF elements which are reflected in the study are: Knowledge; Psychological Skills; Memory, Attention, and Decision Processes; Behavioural Regulation; Physical Skills; Social influence Environmental context and resources Social and professional role and identity; Beliefs about Capabilities; Beliefs about Consequence; Intentions and Goals Reinforcement; and Emotions. COM-B Model elements which are reflected in the study are: Psychological capabilities, Physical capabilities, Social Opportunities, Physical Opportunities, Reflective Motivation, and Automatic Motivation. For the pilot study: many changes were made which have improved the validity and reliability of surveyr. For the quantitative study, The Majority of the participants were White British (96%) from White English, Scottish, Welsh and British background. Also, majority of the participants young adults aged between 18 and 32 (82 %) and more than a half were females (64.5%) and from King’s College London (67.5%). The response rate for the surveyr was very high which was of 97%. Majority of the TDF scales have Cronbach’s alpha between excellent at α 0.883 and acceptable at α 0.711. There were statistical differences between the high and low free sugars intakes among White ethnic groups in the follow TDF domains: knowledge, physical skills, social influence, environment context and resources, beliefs about capabilities, beliefs about consequences, intention, social and professional role and identity (Automatic), and emotions. Also, there were some differences between groups within demograpgic data. There were no significant association between the levels of free sugar intake and the following demographic data: ethnicity, employment, age, gender, Dental Filling Status, Dental Filling History, BMI, Current Health Condition, social classes and districts of living. However, there were significant association between the levels of free sugar intake and the following demographic data: qualifications and house hold status. There were significant correlations between the following TDF factors and free sugars intake: knowledge, psychological skills, memory attention and decision processes,
physical skills, social influences, environment context and resources, beliefs about capabilities, beliefs about consequences, intention, social and professional role and identity (automatic motivation) and emotions. However, these correlations various between negative and positive relationships. The six predictors are: Environment Context and Resources; Social and Professional Role and Identity (Automatic Motivation); Social and Professional Role and Identity (Reflective Motivation); Reinforcement; Beliefs About Consequences; and Beliefs About Capabilities, however, the predictability between these predictors various. The regression identified model three with three significant predictors among White ethnic participants who have dental fillings. The three predictors are: social and professional role and identity (Automatic Motivation), Environment context and resources and physical skills, however, the predictability between these predictors various. In terms of gender, there were differences between male and female in some of the predictors for free sugars intake. For male the predictors are: environment context and resources; social and professional role and identity (automatic motivation); social and professional role and identity (reflective motivation), and knowledge. For female the predictors are: environment context and resources; social and professional role and identity (automatic motivation); reinforcement; beliefs about consequences and physical skills. Not having dental filling is positively predicted free sugar intake.
Conclusion: For the systematic review, there is a need for more clinical trials to assess the effectiveness of interventions based on psychological theory in reducing dietary sugar intake among adults. For the qualitative study, the COM-B model and TDF framework provided a comprehensive account of the barriers and facilitators of reducing sugar intake among White ethnic groups. For the quantitative study, overall, there were different between high and low free sugar intake in relation to TDF domains. The study identified six predictors are: Environment Context and Resources; Social and Professional Role and Identity (Automatic Motivation); Social and Professional Role and Identity (Reflective Motivation); Reinforcement; Beliefs About Consequences; and Beliefs About Capabilities which can be used to develop interventions to reduce free sugar intake among white ethnic groups.
| Date of Award | 2018 |
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| Original language | English |
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| Supervisor | Tim Newton (Supervisor) & Koula Asimakopoulou (Supervisor) |