Evidence-Based Public Health

Objectives and Competencies

Learn the definition of EBPH

Introduction to the process of EBPH

Describe steps associated with EBPH in public

health.

Identifies relevant and appropriate data and

information sources.

Definitions

Evidence

Public Health

Evidence-based Medicine

Evidence-based Public Health

“ …If we did not respect the evidence, we would

have very little leverage in our quest for the

truth.”

Carl Sagan

Evidence

The available body of facts or information

indicating whether a belief or proposition is

true or valid” .

Evidence-based Medicine

apply the best available evidence gained from the scientific

method to clinical decision making 

assess the strength of evidence of treatments and diagnostic

tests.

Evidence quality can range from meta analyses and systematic

reviews of double blind, placebo-controlled clinical trials at the

top end, down to conventional wisdom at the bottom.

Emerge of Evidence-Based Medicine

First described in 1992

A new approach to teaching medicine

A “revolution” in medical practice

Other “evidence-based” approaches: ethics,

psychotherapy, occupational therapy, dentistry,

nursing, and librarianship

Driving Factors of EBM

Overwhelming size of the literature

Inadequacy of textbooks

Difficulty synthesizing evidence and translating

into practice

Increased number of RCTs

Available computerized databases

Reproducible evidence strategies

Definition of EBM

“ The integration of best research evidence

with clinical expertise and patient values.”

Steps of EBM

►Convert the need for info. into an answerable

question

►Track down the best evidence

►Critically appraise that evidence

►Integrate the appraisal with one’s clinical expertise

and the individual patient

►EvaluateSackett DL. EBM: how to practice and teach EBM. Churchill Livingstone 2000

Critique of EBM

De-emphasizes patient values

Doesn’t account for individual variation

Devalues clinical judgment

Leads to therapeutic nihilism

Evidence-based Public Health

Definition: “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 planning

models”

Source: Brownson, R.C. et al, Evidence-based public health, Oxford University Press, 2003.

Development of EBPH

Jenicek (1997) published a review discussing

epidemiology, EBM, EBPH

Epidemiology described as the foundation of

both EBM and EBPH

EBPH unique in using complex interventions

with multiple community and societal issues

Evidence-based Public Health is the leading

edge of modern public health practice

Steps of EBPH

► Develop an initial statement of the issue

► Search the scientific literature and organize

information

► Quantify the issue using sources of existing data

► Develop and prioritize program options; implement

interventions

► Evaluate the program or policy

Community Needs & Values

Scientific Evidence

Resources

(adapted and modified from Muir Gray)EBPH

EBM and EBPH Parallels

State the scientific question of interest

Identify the relevant evidence

Determine what information is needed to

answer the scientific question

Determine the best course of action

considering the patient or population

Evaluate process and outcome

Differences between EBM and EBPH

Characteristic Evidence-Based Medicine

Evidence-Based Public Health

Quality of evidence Experimental studies Observational and quasi-experimental studies

Volume of evidence Larger Smaller

Time from intervention to outcome

Shorter Longer

Professional training of workforce

More formal, with certification and /or licensing

Less formal, no standard certification

Decision making Individual Team

Steps in the EBPH Process1. Define a public health problem;

2. Identify information to solve problems;

3. Searching the literature;

4. Critical appraisal of the evidence;

5. Selecting the best evidence for a public health decision;

6. Linking evidence with public health experience, knowledge, practice,

and the community’s values and preferences;

7. Implementing findings in public health practice and programs

(intervention);

8. Evaluating results.

Source: Jenicek, Milos and Sylvie Stachenko. 2003. Evidence-based public health, community medicine, preventive care. Medical Science Monitor: 9(2): p, SR2.

Evidence-Based Public Health

Define the issue

Quantify the issue Conduct literature

review

Develop program or policy options

Develop planEvaluate the

program or policy

Steps in Searching the Public Health Literature

1. Determine the public health problem and define the

question

2.Select information sources

3.Identify key concept and terms

4.Conduct the search

5.Select documents for review

6.Abstract relevant information from the documentation

7.Summarize and apply the literature review

Source: Adapted from Brownson. Evidence-based public health. Oxford University Press, 2003, p. 128.

Appraising the Evidence & Evaluating the Results

What are the results?

Are the results valid?

How can the results be applied to public

health practice and interventions?

Source: Guide to Research Methods: The Evidence Pyramid: <http://servers.medlib.hscbklyn.edu/ebm/2100.htm>.

Hierarchy of Research Designs

Category I: Evidence from at least one properly

randomized controlled trial.

Category II-1: Evidence from well-designed controlled

trials without randomization.

Category II-2: Evidence from well-designed cohort or case-

control analytic studies, preferably from more than one

center or research group.

Category II-3: Evidence from multiple times series with or

without intervention or dramatic results in uncontrolled

experiments such as the results of the introduction of

penicillin treatment in the 1940s.

Category III: Opinions of respected authorities, based on

clinical experience, descriptive studies and case reports,

or reports of expert committees.

Source: Harris, R.P. et al. (2001). Current methods of the U.S. Preventive Services Task Force: a

review of the process. American Journal of Preventive Medicine. April 20 (3 Supplement): 21-

35

Types of Evidence

Systematic Review: critical assessment and evaluation of research

that attempts to address a focused question using methods designed to reduce

the likelihood of bias.

Meta-Analysis: overview that incorporates a quantitative strategy for

combining the results of several studies into a single pooled or summary

estimate.

Risk Assessment: systematic approach to characterizing the risks

posed to individuals and populations by environmental pollutants and other

potentially adverse exposures.

Decision Analysis: systematic approach to decision making under

conditions of uncertainty; involves identifying all available alternatives and

estimating the probabilities of potential outcomes associated with each

alternative, valuing each outcome, and, on the basis of the probabilities and

values, arriving at a quantitative estimate of the relative merit of the alternatives.

Economic Evaluation: comparative analysis of alternative courses

of action in terms of both their costs and consequences.

Expert Panels: examination of research studies and their relevance to

health conditions, diagnostic and therapeutic procedures, planning and health

policy, and community interventions.

Practice Guidelines: systematically developed statements to

assist practitioner and patient decisions about appropriate health care for

specific clinical circumstances; may be developed by government agencies,

institutions, or by the convening of expert panels.

Source: R.C. Brownson et al, Evidence-Based Public Health, Oxford: Oxford University, 2003.

Evidence spectrum

Meta analysis/ Systematic review/ Evidence-based guidelines

Weak Strong

No evidence/ case reports

Best PracticesLocal needs assessment

“The best is the enemy of the good”-Voltaire

“ The best is the enemy of the

good”

-Voltaire

The effectiveness of parachutes has not been

subjected to rigorous evaluation by using

randomised controlled trials…. We think that

everyone might benefit if the most radical

protagonists of evidence based medicine

organised and participated in a double blind,

randomised, placebo controlled, crossover trial of

the parachute.

Smith and Pell, BMJ, 2004

The problem of randomized trials and parachutes….

PubMed <www.pubmed.gov>

Cochrane Collaboration www.cochrane.org

TRIP Database www.tripdatabase.com/

NICHSR: National Information Center on Health Services Research &

Health Care Technology http://www.nlm.nih.gov/nichsr/nichsr.html

Partners in Information Access for the Public Health Workforce

<phpartners.org> Lamar Soutter Library: EBPH Project

<http://library.umassmed.edu/ebpph/>

Best Evidence Resources

Step 1: Determine/Define the question (Evidence types)

Type 1 Something should be done

Type 2 This should be done

Type 3 How the intervention should be done

Step 1: Determine/Define the question

P =Patient/Population/Problem

I =Intervention/Item of interest

C =Comparison

O =Outcome

You coordinate social activities for a few of the city’s senior

centers. The latest Behavioral Risk Factor Surveillance System

(BRFSS) survey showed that seniors in your state are not

participating in regular exercise or many other health promotion

behaviors. You’ve heard that physical activities for older adults

can have a host of benefits, and would like to submit a grant to

begin an exercise program. You must find literature supporting

the effect of exercise programs in reducing injuries or decreasing

risk of chronic disease in the elderly.

A Scenario

P

I

O

C – no comparison/placebo

I

P = inactive seniors

I = community exercise programs

C = no comparison

O = reduced injuries/chronic disease

PICO

The question…

In inactive senior populations, are formal

exercise programs effective in reducing

injuries and chronic disease associated with

the aging process?

Step 2: Select information sources

Systematic Reviews and Meta-analyses

Practice Guidelines

Journal Literature

Best Practices

Step 3: Identify key concept and terms

In inactive senior populations, are formal

exercise programs effective in reducing

injuries and chronic disease associated with

the aging process?

P = inactive seniors I = community exercise programs C = no comparison O = reduced injuries/chronic disease

Step 3: Identify key concepts and terms

PSeniors/senior

citizenselderlyaged

Iexercisephysical activityrecreation

program developmentprogram evaluationeffective programs

Step 4: Searching the literature

Best Evidence Resources

http://ebling.library.wisc.edu/EBPH