Understanding the role of evidence in e-cigarette regulation and policy development

Background: Public health recommendations should be informed by the best available evidence. E-cigarette policy has varied across jurisdictions, contrasting with the previous coordinated approach of international tobacco control communities. An understanding of such divergence may help inform future public health policy. Using e-cigarettes as a case study, this thesis examines the role and use of evidence in the development of public health recommendations. Methods: This multi-methods case study focused on e-cigarette recommendations from the WHO, UK, Australia, and USA; and comprised: a document analysis of recommendations; a citation network analysis of the evidence cited and their conflicts of interest (COI); an analysis of the guideline development documents which described the processes for developing recommendations, including managing COI; expert interviews with individuals involved in developing recommendations; and triangulation across these data sources. Results: Analysis of public health recommendations showed that different jurisdictions supported different e-cigarette policy approaches, with the UK following a ‘harm reduction’ approach, while the WHO, Australia, and USA followed a more ‘precautionary’ approach. Analysing the evidence cited by the recommendation documents revealed that substantial COI, such as pre-existing relationships between the e-cigarette and tobacco industries, were present within the cited evidence. Examination of the processes for collecting and managing COI, illustrated variation across public health bodies, often with a lack of transparency. Triangulating across the data demonstrated the myriad contextual factors (e.g., previous and current tobacco policies) influencing the role and use of evidence in the development of e-cigarette recommendations. I highlight how internal contextual factors (e.g., the remit of the document) were often influenced by external contextual factors (e.g., epidemiological features of smoking and vaping) and interact in subtle ways to frame the focus of recommendations and the evidence underpinning them. Conclusion: Contextual factors are crucial in understanding divergence in e-cigarette recommendations across jurisdictions, with similar evidence used by public health bodies internationally. COI are common in the evidence base and a lack of standardisation in managing COI might threaten evidence-informed decision-making. This thesis suggests internal and external contextual factors interact and that this interplay may help explain the divergence in e-cigarette policy approaches