Using realist methods for intervention development to fill a methodological gap: A case study showing the development of an oral hygiene intervention for people with intellectual developmental disabilities.

BACKGROUND: Realist methods offer a novel approach to intervention design. Such novelty is needed for effective oral health promotion interventions with people with intellectual developmental disabilities (IDD) and their carers because existing interventions are poorly described and lack theoretical underpinning. In this study, the steps between inception and final intervention development are presented, with an aim to expand understanding of how realist theorizing can be used to develop interventions, and to demonstrate theory-driven intervention development in the field of oral health promotion.

METHODS: In this intervention development study, the use of realist methods to develop an intervention aiming to improve the oral hygiene of people with IDD is presented. Realist theories (RTs) arising from a mixed synthesis were used to develop the Keep My Teeth intervention. The use of realist theory in intervention development was mapped across seven domains and 18 actions with emphasis on how theory informed key actions.

RESULTS: Realist theories informed many but not all actions in the development process. Where gaps arose, this was augmented with other systems of intervention development, such as the Behaviour Change Wheel (BCW) and Behaviour Change Technique (BCT) systems. The resulting intervention and underlying theory are presented using TiDieR criteria.

CONCLUSIONS: It is demonstrated how realist methods could be integrated with substantive theory when developing an intervention. RTs enhanced the contextualization of the intervention that was developed but were insufficient in their own right to guide the development process from conception to intervention. This was overcome by augmenting with substantive theory, in this case, using the BCW and BCT behaviour change systems, to select and specify the behaviours that needed to change. In essence, the BCTs guided which techniques to select, while the RTs guided how to develop and intervene. Robust intervention development in the field of oral health promotion is also presented in this study.