Docfan Academy

1. Definitions and development

• Evidence-based medicine (EBM): the conscientious, explicit and judicious use of current best evidence in decisions about the care of individual patients (Sackett and colleagues, 1996). It integrates the best research evidence with clinical expertise and the patient’s values.
• Evidence-based public health (EBPH): the process of integrating science-based interventions with community preferences to improve the health of populations (Kohatsu, Brownson and colleagues). Jenicek defined it as the use of the best available evidence in decisions about the care of communities and populations in health protection, disease prevention and health promotion.
• Evidence-informed policy: recognises that research is one input among others (resources, politics, values, context).

Milestones: Archie Cochrane’s 1972 book Effectiveness and Efficiency called for randomised trials and for systematic summaries of them; the Cochrane Collaboration began in 1993; EBM was promoted by Guyatt, Sackett and colleagues in the early 1990s; the US Community Preventive Services Task Force and its Community Guide in the 1990s; WHO’s Evidence-Informed Policy Network (EVIPNet) in 2005; and WHO’s Guidelines Review Committee (2007) with the GRADE method for developing guidelines.

2. Rationale

• Resources are scarce: we must spend them on what works.
• Some popular interventions are ineffective or harmful (for example ‘scared straight’ programmes for delinquents, and some drug education programmes).
• Programmes are more likely to be effective, efficient and equitable, and public money is better used.
• Transparency and accountability to communities and funders.
• Better and faster decisions in emergencies, as shown by the improvement of TB regimens or vaccination schedules after new evidence.

3. Steps in EBM and EBPH

EBM: the five A’s. (1) Ask a focused, answerable question using PICO (Population, Intervention, Comparison, Outcome); (2) Acquire the best evidence (databases such as PubMed, Cochrane Library, WHO guidelines); (3) Appraise it for validity, size of effect and applicability; (4) Apply it with the patient’s values and circumstances; (5) Assess the result.

EBPH: seven steps (after Brownson and colleagues):

• 1. Community assessment: engage the community and understand its needs and assets.
• 2. Quantify the issue: use data on size, trends and inequalities.
• 3. Develop a concise issue statement (problem, who is affected, causes, size, solutions).
• 4. Determine what is known: search for systematic reviews, guidelines and local studies.
• 5. Develop and prioritise options for programmes and policies.
• 6. Develop an action plan and implement.
• 7. Evaluate the programme or policy and use the results.

4. Similarities and differences between EBM and EBPH

What they share: both use explicit methods to find, appraise and use the best available evidence, and both must monitor the results of what they do.

5. Types of evidence and the hierarchy

Brownson’s three types of evidence: Type 1 tells us the size, severity and preventability of a problem (what should we do?); Type 2 tells us which interventions work (what works?); Type 3 tells us how to implement them in a given setting (how and where?). Public health usually has plenty of Type 1 evidence, less of Type 2 and the least of Type 3.

The hierarchy of evidence for questions on the effects of interventions, from strongest to weakest: systematic reviews and meta-analyses of randomised trials; randomised controlled trials; cohort studies; case-control studies; cross-sectional studies and case series; expert opinion. Qualitative studies are needed to understand acceptability and implementation. The hierarchy is a guide, not a rule: a poorly done trial can be less reliable than a well-done cohort study.

GRADE (Grading of Recommendations, Assessment, Development and Evaluation) rates the certainty of evidence as high, moderate, low or very low, based on risk of bias, inconsistency, indirectness, imprecision and publication bias (it can be upgraded for large effects). It rates the strength of a recommendation as strong or conditional using an evidence-to-decision framework that also considers benefits and harms, values, resources, equity, acceptability and feasibility. WHO uses this method for its guidelines.

6. Appraising evidence quickly

• Is the question clear and relevant to my population?
• Is the design appropriate? Were groups comparable? Is there a risk of bias or confounding?
• How large is the effect (risk ratio, absolute risk reduction) and how precise (confidence interval)?
• Is it applicable here (setting, resources, culture, equity)?
• Are there conflicts of interest? Is the source reliable and up to date?

7. Knowledge translation and use

Knowledge translation is the process of synthesis, dissemination, exchange and ethically sound application of knowledge to improve health. Evidence does not use itself. Common barriers are lack of time, skills and access; evidence not in the right form; weak links between researchers and decision makers; competing political priorities; and lack of resources. Strategies include: involving decision makers in framing questions; evidence briefs and policy dialogues (EVIPNet); rapid reviews for urgent decisions; training; embedded researchers; using local data in dashboards; and implementation science frameworks (RE-AIM, CFIR) to plan adaptation and scale-up.

8. Evaluating and improving evidence-based practice

Ask whether each step of EBPH was done well and whether it improved health. Monitor process (was the programme delivered as planned?), outcome (did knowledge, behaviour or service use change?) and impact (did health improve and did inequalities fall?). Use cycles of quality improvement (plan-do-study-act), audits, feedback to teams, and learning from failure. Build capacity: libraries, access to journals, critical appraisal skills, and data systems.