Philosophical reflections on evidence-based publich health

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

2. The fat generation 2

3. 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 … 3

4. Causes and effects What are the causes (and mechanisms) 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, equipment in hospitals, average passengers weight implications for fuel used by airlines, ... 4

5. Something must be done Public health actions Worksite health promotion programmes School-based interventions Information on healthy eating … What evidence to inform public health actions? 5

6. A plea forcausally-basedpublic health 6

8. Each has a different role in informing actionsA 3-step argument Public health and epidemiology A population-level perspective on disease causation Evidence-based public health What evidence is left largely unanswered Causally-based public health Causal assessment has 2 evidential components: difference-making and mechanisms 7

9. Public health and epidemiology 8

10. Public-health is population-level PH aims to preventing disease, prolonging life, promoting health of populations Actions to achieve those aims are based on population-level analyses Epidemiology is essential for public health 9

11. Epidemiology and disease causation Epidemiology Distributions of disease within / across populations Biological and socio-economic determinants Descriptive epidemiology Who, what, when, where Focus: risks of exposure Analytic epidemiology How and why Focus: (i) measures of associations to identify causes of disease, (ii) reinforcing causal hypotheses with mechanistic explanations 10

12. Two goals of epidemiology To understand and learn about population-level causes of disease To take action in order to reduce the burden of disease at population level 11

13. 1.Understanding and learning about disease Drawing causal conclusions from evidence What evidence for disease causation is upfront Difference-Making Mechanisms 12

14. evidence-based public health 13

15. 2.Taking action to reduce the burden of disease Action based on evidence 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. Killoran and Kelly (2010, p. xxii) 14

16. Evidence galore 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 15

17. But what evidenceserves what purpose?

18. Causally-based public health 17

19. The underlying intuition Better understanding Better decisions and actions Public health policy: Better understanding of disease Better interventions to reduce the burden of disease. If understanding disease causation involves different types of evidence Then different types of evidence serve different roles in public health policy 18

20. A key feature: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) Whatevidence gives us such information? 19

21. What works for whomin what circumstances 20

22. Difference-making evidence Correlations, probabilistic and counterfactual dependencies, etc. This is typically provided by descriptive epidemiology informing about who, what, when, where Target: (what) populations, groups individuals, … Factors: biological, social, economic, … 21

23. For instance Local and national cancer registers; obesity databases; Projects of the Executive Agency for Health and Consumers Projects listed under policy actions are oft exploratory: They generate difference-making evidence to inform public health actions. E.g.: prevention in children or particular classes of professionals 22

24. Causal pathways 23

25. Mechanistic evidence Analytic epidemiology tests explanatoryhypothesessuggested by descriptive epidemiology That is, mechanistic hypotheses answering questions about how and why 24

26. For instance Studies on type 2 diabetes and on mechanisms for insulineresistance or endocrine deregulation Studies on changes in dietary habits due to changes in socio-economic environments … Motivation: descriptive studies that discovered neat correlations and that identified high risks 25

27. Mechanisms vs difference-making No ‘conceptual’ priority of one type of evidence over the other Yet, true: different types of evidence may have unequal weights in assessing different hypotheses of disease causation 26

28. To sum up and conclude Causation, Mechanisms, Evidence, Action Studies on obesity and public health programmes What evidence should inform public health actions? Public health, evidence, and causation Public health and epidemiology Epidemiology and evidence Evidence and causation Causally-based public health 27

29. 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. 28