1. Public health policy, evidence, and causationLessons from the studies on obesity Federica Russo Philosophy, Kent

2. Prologue 2

3. Causality Across the Levels:Biomedical Mechanisms and Public Health Policies A British Academy funded project at Kent Genuine distinction between generic and single-case Yet, poorly understood, crucial questions remain Different notions at different levels? How to draw inferences from one level to another? How socio-economic variables affect health variables (and vice-versa)? … 3

4. Food for thought Studies on obesity provide a diversified and balanced philosophical diet Multi-level Mechanism Evidence Action … 4

5. The fat generation 5

6. Facts In more and more Member States of EU More than 20% adult population is obese More than 50% adult population is overweight Up to 20% of children are overweight Check out stats: http://www.hopeproject.eu/index.php?nav_id=1 http://www.ic.nhs.uk/statistics-and-data-collections/health-and-lifestyles/obesity/statistics-on-obesity-physical-activity-and-diet-england-2010 http://www.who.int/mediacentre/factsheets/fs311/en/index.html … 6

7. Causes and effects What are the causes of obesity? What are the causes of the increased prevalence of obesity? Health effects: cardiovascular diseases, cancer, diabetes … Socio-economic effects: standard seat width increased, office furniture, average passengers weight implications for fuel used by airlines, equipment in hospitals .. 7

8. Something must be done Public health actions Worksite health promotion programmes School-based interventions Information on healthy eating … What should we base public health actions upon? 8

9. A plea for causally-based public health 9

10. Overview Take-home message Public health actions need 3 types of evidence, having each a different role in informing actions A 3-step argument Public health and epidemiology. A population-level perspective on disease causation Evidence-based public health. Evidence assessment isn’t enough Causally-based public health. Causal assessment has 3 evidential components: difference-making, levels, mechanisms 10

11. Public health and epidemiology 11

12. Public-health is population-level PH aims to: Preventing disease Prolonging life Promoting health Actions to reach those aims are based on population-level analyses Epidemiology is essential for public health 12

13. Epidemiology and disease causation Epidemiology studies how the distributions of disease and their biological and socio-economic determinants vary within and across different populations. Descriptive epidemiology Who, what, when, where. Focus on risks of exposure. Analytic epidemiology How and why. Focus on measures of associations to identify causes of disease, reinforce causal hypotheses with mechanistic explanations 13

14. Two goals of epidemiology, arguably (1) To understand and learn about disease and (2) To take action in order to reduce the burden of disease at the population level Drawing causal conclusions from evidence Questions about what evidence for disease causation are upfront Difference-Making & Levels Mechanisms [See also Russo & Williamson (2007 and 2011)] 14

15. evidence-based public health 15

16. (2) Taking action to reduce the burden of disease Evidence-based public health is defined as the development, implementation, and evaluation of effective programs and policies in public health through application of principles of scientific reasoning, including systematic uses of data and information systems, and appropriate use of behavioral science theory and program. (Brownson et al., 2003) Evidence-based public health is the process involved in providing the best available evidence to influence decisions about the effectiveness of policies and interventions and secure improvements in health and reductions in health inequalities. Killoranand Kelly (2010, p. xxii) 16

17. Evidence galore EBPH inherits from epidemiology crucial questions about evidence Evidence on focus Evidence on which one’s practice or policy is based Soundness of evidence Strength of inference permitted by evidence … Whence the importance of evidence-assessment to assess the best evidence 17

18. But what evidence serveswhat purpose?

19. Causally-based public health 19

20. The underlying intuition Arguably, making good decisions and taking good actionsdepend on having a good understanding of the phenomenon or situation. In public health policy, the better our understanding of the disease, the better too the interventions to reduce the burden of disease. Thus, if we accept the idea that understanding disease causation involves making considerations about different types of evidence, then those different types of evidence will also serve different roles in setting public health policies. 20

21. A key feature of EBPH:Conceptual plausibility “An understanding of causal pathways defining the factors influencing health and the potential for intervention; use of different types of evidence to determine what works for whom in what circumstances.” (Killoran & Kelly 2010) What evidence gives us such information? 21

22. What works for whomin what circumstances 22

23. Difference-making evidence Correlations, probabilistic and counterfactual dependencies, etc. This is typically provided by descriptive epidemiology Informs about who, what, when, where. 23

24. Evidence about the levels ‘Vertical’ level Whether interventions have to target the whole population, or only subgroups or individuals that fall under certain categories; ‘Horizontal’ level Whether it is most efficient to intervene on the social or biological factors of disease (or on both simultaneously) [See also Russo (2009) and (2010)] 24

25. For instance The work done in local and national cancer registers or in obesity databases Research conducted in a number of projects promoted by the Executive Agency for Health and Consumers Nota Bene Those projects are listed under policy actions but are in fact exploratory: inform actions such as prevention in children or particular classes of professionals 25

26. Causal pathways 26

27. Mechanistic evidence Studies to test epidemiological hypotheses coming from descriptive epidemiology Analytic epidemiology Tests explanatory causal hypotheses That is, mechanistic hypotheses Answer questions about how and why 27

28. For instance Studies on type 2 diabetes and on mechanisms regulating insulineresistance endocrine deregulation syndromes Studies on changes in dietary habits due to changes in socio-economic environments … Motivation: descriptive studies that discovered neat correlations and identified high risks 28

29. Mechanisms and Levels Mechanistic evidence is concerned about the levels of causation too Average mechanisms vs single-case mechanisms No ‘conceptual’ priority of one type of evidence over the other True, different types of evidence may have unequal weights in assessing different hypotheses of disease causation 29

30. To sum up and conclude 30

31. Multi-level, Mechanism, Evidence, Action Studies on obesity and public health programmes What should be base public health actions upon? Public health, evidence, and causation Public health and epidemiology Epidemiology and evidence Evidence and causation Causally-based public health 31

32. Selected bibliography Brownson, R. C., andT. L. Leet, E. A. B., and Gillespie, K. N. (2003). Evidence-Based Public Health. Oxford University Press, New York. Cartwright, N. (2008). Evidence for evidenced-based policy. Talk at a Home Office Seminar on Criminology and Evidence-Based Policy. Cartwright, N. (2009). Causality, invariance, and policy. In Kincaid, H. and Ross, D., editors, The Oxford Handbook of Philosophy of Economics, chapter 15, pages 410{421. Oxford University Press. Glasziou, P., Chalmers, I., Rawlins, M., and McCulloch, P. (2007). When are randomised trials unnecessary? Picking signal from noise. British Medical Journal, 334:349-351. Greener, J., Douglas, F., and van Teijlingen, E. (2010). More of the same? Conflicting perspectives of obesity causation and intervention amongst overweight people, health professionals and policy makers. Social Science & Medicine, 70:1042-1049. Guyatt, G. and Drummond, R. (2002). Users Guides to the Medical Literature: A Manual for Evidence-Based Practice. American Medical Association, Chicago. Killoran, A. and Kelly, M. P., editors (2010). Evidence-based public health. Effectiveness and efficiency. Oxford University Press, New York. Philipson, T. and Posner, R. (2008). Is the obesity epidemic a public health problem? A decade of research on the economics of obesity. Technical Report Working paper 14010, The National Bureau of Economic Research. Power, M. and Schulkin, J. (2009). The evolution of obesity. The John Hopkins University Press, Baltimore. Riboli, E. and Lambert, R., editors (2002). Nutrition and lifestyle: opportunities for cancer prevention. Number 156. IARC Scientic publications. Russo, F. (2009). Variational causal claims in epidemiology. Perspectives in Biology and Medicine, 52(4):540-554. Russo, F. (2010). Causal webs in epidemiology. Paradigmi. Russo, F. and Williamson, J. (2007). Interpreting causality in the health sciences. International Studies in Philosophy of Science, 21(2):157-170. Russo, F. and Williamson, J. (2011). Generic vs. single-case causal knowledge. The case of autopsy. European Journal for Philosophy of Science. Rychetnik, L., Hawe, P., Waters, E., Barratt, A., and Frommer, M. (2004). A glossary for evidence based public health. Journal of Epidemiology and Community Health, 58:538-545. 32