Introduction to EBM

dr. Ryan Herardi

What is evidence-based medicine?“Evidence-based medicine is the integration of best research

evidence with clinical expertise and patient values” - Dave Sackett

Patient Concerns

Clinical Expertise

Best research evidence

EBM

History• In the Past– Ancient Chinese medicine– Post-revolutionary Paris

• In the current era, – named EBM in 1992 by a group led by Gordon

Guyatt at McMaster University in Canada

How do we actually practice EBM

Asking

• Background questions– General knowlegde about a disorder– (5W + H) + (a disorder / aspect of a disorder)

• Foreground questions– Specific knowledge about managing patients– PICO

PICO

• P = Patient / Population / Problem• I = Intervention / Indicator / Index• C = Comparation (if relevant)• O = Outcomes

PICO

The uses of EBM• Improving outcomes for patients (no such

evidence)• Improving clinical communication skills• Improving skills for use in finding, appraising,

and implementing evidence• Doing a new research ?

TypesDiagnosis how to select and interpret diagnostic tests

Therapyhow to select treatments to offer patients that do more good than harm and that are worth the efforts and costs of using them

Prognosishow to estimate the patient's likely clinical course over time and anticipate likely complications of disease

Harm/Etiology how to identify causes for disease (including iatrogenic forms)

VIA methods

• Validity: type of study, blinded?, number of subjects?, controlled?

• Importance: result?• Applicability: patient’s characteristic

Levels of Evidence

What do we need ?

Find Evidence

Develop a search strategy

Using OR then AND to broaden then focus the search

P I O

Sore throat* or

tonsillitis or

pharyngitis

Antibiotic* or

antibacterial*or

penicillin

Symptom relief or

Symptom alleviation

and and

Combine terms withOR

pharyngitis

Sore throat

Pharyngitis OR sore throat – either term can be present

Combine terms withAND

Antibiotics AND sore throat – both terms must be present

sore throatantibiotics

PubMed demonstrationwww.pubmed.gov

Pubmed

Pubmed

The Cochrane Library

• Specialist database including articles on clinical and cost effectiveness of interventions:– Systematic reviews – Cochrane Database of Systematic

Reviews & DARE– RCTs – Central– Economic evaluations - NHSEED

• Free access in the UK at http://www.thecochranelibrary.com

• Other countries check “access options” at http://www.cochrane.org

Practice

“Practice makes perfect, but nobody's perfect, so why practice?” ― Kurt Cobain

Scenario

Gerry, has had a bad throat for a few days and it’s making him feel miserable. He goes to his

friendly GP wanting some antibiotics. However, his doctor isn’t sure whether there’s any benefit in prescribing them.

What’s the evidence?

Example 1Jean is a 55 year old woman who quite often crosses the Atlantic to visit her elderly mother. She tends to get swollen legs on these flights and is worried about her risk of developing deep vein thrombosis (DVT), because she has read quite a bit about this in the newspapers lately. She asks you if she would wear elastic stockings on her next trip to reduce her risk of this.

Type :PICO

Example 2Susan is expecting her first baby in two months. She has been reading about the potential benefits and harms of giving newborn babies vitamin K injections. She is alarmed by reports that vitamin K injections in newborn babies may cause childhood leukaemia. She asks you if this is true and, if so, what the risk for her baby will be.

Type :PICO

Example 3

Julie is pregnant for the second time. She had her first baby when she was 33 and had amniocentesis to find out if the baby had Down Syndrome. The test was negative but it was not a good experience, because she did not get the result until she was 18 weeks pregnant. She is now 35 and 1 month pregnant, and asks if she can have a test that would give her an earlier result. The local hospital offers serum biochemistry plus nuchal translucency ultrasound screening as a first trimester test for Down syndrome. You winder if this combination of tests is as reliable as a conventional amniocentesis

TypePICO

Example 4

Mr Thomas, who is 58 years old, has correctly diagnosed his inguinal lump as a hernia. He visits you for confirmation of his diagnosis and information about the consequences. You mention the possibility of strangulation, and the man asks ‘How likely is that?’ You reply ‘pretty unlikely’ (which is as much as you know at the time) but say that you will try to find out more precisely.

TypePICO

Your Clinical Questions• Write down one recent patient problem

• What is the PICO of the problem?