Background: A Theory of Change (ToC) is a comprehensive description and illustration of how and why a desired change is expected to happen in a particular context. The use of a ToC, and collecting data on outcomes along the causal chain, can be helpful in attempts to explain effect-size heterogeneity and to better understand differences in findings by context, when developing a systematic review.
Objectives: To describe the added value of a ToC throughout the conduct of a MMSR about the effectiveness (quantitative arm MMSR) and implementation (qualitative arm MMSR) of sanitation and handwashing promotion programmes on behaviour change.
Methods: The development of the initial ToC was based on relevant systematic reviews, existing WASH behavioural models and frameworks on contextual/implementation factors. The ToC was further adapted by stakeholder input (4 development practitioners/1 donor/1 topic expert/2 qualitative research experts). Based on the evidence gathered from the MMSR and more extensive stakeholder involvement (13 development practitioners/consultants/3 policy makers/2 topic experts/2 qualitative research experts/4 donors), final adaptations to the ToC were made (Figure 1).
Results: The ToC helped us in different steps of the MMSR process. Firstly, the ToC was used to fine-tune the selection criteria of our MMSR (e.g. distinction between primary and secondary outcomes). Secondly, it was used as the a-priori model in the 'Best fit framework synthesis' (qualitative evidence synthesis methodology) which synthesised the qualitative research data on implementation factors of sanitation and handwashing programmes. Thirdly, the iterative process of ToC development created a sense of ownership and stakeholder buy-in and clarified the research focus of the MMSR. Finally, we projected the final conclusions of our MMSR on the ToC.
Conclusions: An evidence-based ToC guides researchers before, during and after the conduct of an MMSR and it will help policy makers to understand the important role of implementation, and the processes determining behaviour change in handwashing and sanitation.