Evidence Based Public Health

John SandarsHonorary Senior Lecturer

It’s about making sense of what we do ….

And why we do it

On Dec, 31, 1664, Samuel Pepys, taking stock of the past year, confided to his diary:

“I bless God, I never have been in so good plight as to my health … but I am at a great loss to know whether it be my Hare's foot, or taking every morning a pill of Turpentine, or my having left off the wearing of a gowne”.

Making A Decision

• Need for evidence

- information that I can believe!

• Making a judgment

– competing demands

THE EVIDENCE

Prospective controlled trial (1753)

First RCT (1948)

Systematic Reviews (1972)

Rise of Evidence-Based Medicine

• First described in 1992

• A new approach to teaching medicine

• A “revolution” in medical practice

Definition of EBM

“The integration of best research evidence with clinical expertise and patient values.”

Sackett DL. EBM: how to practice and teach EBM.2000

Steps of EBM

• Convert the need for information into an answerable question

• Track down the best evidence

• Critically appraise that evidence

• Integrate the appraisal with clinical expertise and the individual patient

• Evaluate

Sackett DL. EBM: how to practice and teach EBM.2000

Jenicek M. J Epidemiol 1997;7:187-97

Definition of EBPH

“EBPH is the conscientious, explicit, and judicious use of current best evidence in making decisions about the care of communities and populations in the domain of health protection, disease prevention, health maintenance and improvement.”

Steps of EBPH

• Access the evidence – Variety of different sources since complex

problems and different perspectives

• Appraise the evidence

• Apply the evidence

Steps of EBPH

• Access the evidence • Appraise the evidence

• Apply the evidence–complex system–different perspectives–evaluate the fit

Implementing evidence based medicine in general practice: audit and qualitative study of antithrombotic treatment for atrial fibrillationHowitt A & Armstrong D (1999)

British Medical Journal 318 :1324–1327

Difficulties in closing the evidence to practice gap:

• previous experiences (including minor bleeding)• difficulty of organizing anticoagulation in elderly patients• relationship and knowledge of the individual patient

Low carbohydrate-high protein diet and incidence of cardiovascular diseases in Swedish women: Prospective cohort study.

Lagiou P, Sandin S et al. BMJ 2012; DOI:10.1136/bmj.e4026.

Internal Validity (Biases)

• Sample• Adherence to diet over time• Confounding lifestyle factors• Outcome – single questionnaire

External Validity

• Population