Evidence and Causality in the Sciences. University of Kent. 5 th -7 th September 2012 Professor Mike Kelly, Director of the Centre for Public Health Excellence, The National Institute for Health and Clinical Excellence (NICE) and Institute of Public Health University of Cambridge. How should the evidence hierarchy be developed: a view form a guidance producer.

NICE The National Institute for Health and Clinical Excellence (NICE) is the independent organisation in the UK responsible for providing national guidance to the NHS and the wider public health community on the promotion of good health and the prevention and treatment of ill health. Has had a public health role since 2005 and a role in social care from 2012

The task from 2005 To apply the principles of EBM to public health.

NICE methods for public health S econd edition (April 2009) The NICE public health guidance development process An overview for stakeholders, including public health practitioners, policy makers and the public

The RCT maximises internal validity by reducing bias It allows the reasonable conclusion that the effect that is being witnessed is the consequence of the intervention. By controlling out of the process factors that could contaminate the relationship between the independent and dependent variable, the observer has as much certainty as possible that the relationship is real rather than an artefact of the research process or some other variables confounding the relationship.

The hierarchy of evidence represents levels of types of evidence where internal validity is improved at each succeeding step up the hierarchy. With each step up the hierarchy, the chances of bias are lessened. RCTs score highly because their raison d’eˆtre is the controlling out of factors, which can cause bias.

The hierarchy of evidence

The importance of the causal pathway. Of necessity we have to interested in the causal pathway from the intervention to the outcome. In interventions involving human behaviour, social organisations and economic and political dimensions pathways are complex.

XY K J I D H C G BA F E L

Placement in the hierarchy tells about the quality of the study and the relationship between the intervention and the outcome but not necessarily much about the intermediate steps in the causal pathway. Information on the intermediate steps has to be derived in other ways and from other sources. Need to attend to context and external validity/ transferability.

Individual and population levels in public health. The importance of distinguishing between the individual level explanation and the social level explanation.

Some concluding thoughts. We are frequently dealing with non-commensurate entities. Commensurate regularities do not necessarily reveal cause.

References KELLY, M.P. (2009) The individual and the social level in public health, in Killoran, A. & Kelly, M.P. (eds), Evidence Based Public Health: Effectiveness and Efficiency, Oxford : Oxford University Press. SWANN, C., OWEN, L.,CARMONA, C., KELLY, M.P., WOHLGEMUTH, C., HUNTLEY,J. (2009) A nudge in the right direction: developing guidance on changing behaviour, in Killoran, A. & Kelly, M.P. (eds), Evidence Based Public Health: Effectiveness and Efficiency, Oxford : Oxford University Press.. BAXTER, S. KILLORAN, A., KELLY, M.P., GOYDER. E. (2010) Synthesising diverse evidence: the use of primary qualitative data analysis methods and logic models in public health reviews. Public Health 124: KELLY, M.P. (2010) The axes of social differentiation and the evidence base on health equity. Journal of the Royal Society of Medicine, 103: , DOI.1258/jrsm KELLY, M.P. (2010) A theoretical model of assets: the link between biology and the social structure. In Morgan, A. Davies, M., Ziglio, E. (eds) Health Assets in a Global Context: Theory, Methods, Action,, New York: Springer. KELLY, M.P., MORGAN, A., ELLIS, S., YOUNGER, T., HUNTLEY, J., SWANN, C. (2010) Evidence based public health: A review of the experience of the National Institute of Health and Clinical Excellence (NICE) of developing public health guidance in England, Social Science and Medicine, 71 : KELLY, M.P. & MOORE, T.A. (2011) The judgement process in Evidence Based Medicine and Health Technology Assessment. Social Theory and Health, advance online publication, 14 December 2011; doi: /sth