Using Evidence To Improve Public Health Infrastructure: Let the evidence guide our actions

2. January 7, 2004 Jonathan E. Fielding, M.D., M.P.H., M.B.A Director of Public Health and Health Officer L.A. County Department of Health Services Chair, CDC Task Force of Community Preventive Services Professor of Public Health and Pediatrics University of California, Los Angeles Using Evidence To Improve Public Health Infrastructure: Let the evidence guide our actions

3. If we did not respect the evidence, we would have very little leverage in our quest for truth Carl Sagan

4. Quality of the Evidence • We hear about it often • TV Networks • Usually related to high profile trials • Public Health evidence is different than legal evidence • It is the available information on a particular question • We want the best available evidence in making decisions

5. Decisions and Evidence • Evidence takes many forms • Opinion of leaders • Opinion of “experts” • Studies without controls • Studies with controls • Studies of variable quality in design and execution

6. Decisions and Evidence • Our commitment: • Improve public health • Health problems well defined • Our job: • Make a difference through policies and programs • Inaction is not an option • Hard to identify best evidence to inform decision making

7. Decisions and Evidence • Decisions on policies and programs are often made based on: • Personal experience • What we learned in formal training • What we heard at a conference • What a funding agency required/ suggested • What others are doing

8. Evidence and Public Health Decision Making • Good news • Strong evidence on the effect of many policies/ programs aimed to improve public health • Major efforts underway to assess the body of evidence for wide range of public health interventions

9. What works to improve the public’s health? • Bad news • Many public health professionals are unaware of this evidence • Some who are aware don’t use it • Many existing disease control programs have interventions with insufficient evidence –while others use interventions with strong evidence of effectiveness • Lack of use of effective interventions can adversely affect fulfilling mission and getting public support

10. How do we know what works in improving the health of populations? Background • Many community health improvement efforts have not achieved desired results • Interventions often chosen based on opinions and personal preferences • Evidence based medicine---Clinical Preventive Services Task Force –mid 80s • Evidence based population health --- Community Preventive Services Task Force– mid 90s

11. Systematic Search for the Best Evidence • U.S. Community Preventive Services Task Force Appointed by CDC Director in 1996 • Non-Federal independent task force of experts in multiple relevant disciplines • Epidemiology • Public Health Practice • Behavioral Sciences • Evidence based medicine/ public health • Other relevant areas of expertise

12. Goals • Conduct careful analytic reviews of acceptable evidence for population health interventions and make related recommendations • Use peer reviewed literature • Standard rules of evidence • Standard rules for translating evidence into recommendations for interventions

13. Systematic Reviews of Public Health Interventions are Useful • Methods first developed by social scientists (e.g., Glass, ‘76) • Distill and summarize large and diverse bodies of evidence • Reduce errors and biases in interpretation • Make assumptions explicit

14. Systematic Reviews Are Not: • Limited to randomized controlled trials • Limited to healthcare interventions • Restricted to a “biomedical model” of health - Petticrew, 2001

15. Task Force on Community Preventive Services Members • George J. Isham • Robert L. Johnson • Garland Land • Patricia A. Nolan • Dennis E. Richling • Barbara K. Rimer • Steven Teutsch • Jonathan E. Fielding, Chair • Patricia Dolan Mullen, Vice-chair • Noreen M. Clark • John M. Clymer • Mindy T. Fullilove • Alan Hinman Consultants Robert S. Lawrence J. Michael McGinnis Lloyd F. Novick

16. Who Is the Audience? • People who plan, fund, or implement public health services and policies for communities and healthcare systems • Public health departments • Healthcare systems and providers • Purchasers • Government agencies • Community organizations

17. Community Guide Topics

18. Methods for Systematic Reviews of Effectiveness Evaluations • Develop conceptual framework • Search for and retrieve evidence • Rate quality of evidence • Summarize evidence • Translate strength of evidence into finding • Strongly recommended • Recommended • Insufficient evidence

19. Reduced Disease Instance Logic Framework: Vaccine Preventable Disease Treatment Increasing Enhancing Provider- of Vaccine- Community Access to Based Demand for Preventable Interven tions Vaccina tions Vaccinations Diseases Vaccine- Attendance in Morbidity Public, Private, or Preventable and Population Joint Healthcare Disease Mortality Systems Vaccination Coverage Intervention Types Determinants Exposure to Intermediate Outcomes Vaccine- Environment Preventable Disease Public Health Outcomes Reviewed Reducing Not Reviewed Exposure

20. Standardized Analysis Process • Systematic review of literature • Abstracting of relevant studies • Grading of evidence • Study design • Execution • Translating from quality of evidence to recommendations • Economic analysis • Other benefits and harms

21. How Does the Task Force Define Suitability of Study Design? • Greatest • Prospective with concurrent comparison • Moderate • Multiple before-and-after measurements but no concurrent comparison OR • Retrospective • Least • Single group before-and-after • Cross-sectional

22. What Factors Determine Quality of Execution? • Description of intervention and study population • Sampling procedures • Exposure and outcome measurements • Approach to data analysis • Interpretation of results • Follow-up • Confounding • Other bias • Other issues

23. How Does the Task Force Draw an Overall Conclusion About the Strength of a Body of Evidence? • Number of studies • Design suitability • Quality of execution • Consistency • Effect size

25. Physical Activity:Review of One Intervention • Goal: increase the amount of time students spend doing moderate or vigorous activity in PE class through curricular change • Interventions reviewed included changing the activities taught (e.g., substituting soccer for softball) or modifying the rules of the game so that students are more active (e.g., in softball, have the entire team run the bases together when the batter makes a base hit). Many interventions also included health education.

26. School Curricular Interventions to Improve Physical Fitness • 14 acceptable studies; in all students’ physical fitness improved. • 5 studies measured activity levels during PE class; all found increases in • amount or percentage of time moderately/ vigorously active and/or • intensity level of physical activity during class. • Median estimates--modifying school PE curricula as recommended will result in an 8% increase in aerobic fitness

27. School Curricula to Improve Physical Activity • Modifying school P.E. curricula was effective across diverse racial, ethnic, and socioeconomic groups, among boys and girls, elementary- and high-school students, and in urban and rural settings. • In a separate literature review, having students attend school PE classes was not found to harm academic performance. • Economic analysis pending.