Evidence Based Medicine

Noha Salah Baghdady, M. Sc.

Learning Objectives • Clinical Questions types .• A Hierarchy of Preprocessed Evidence.• EBM definition and value.• Knowledge and Skills Necessary for Optimal

Evidence-Based Practice. • Basic computer and internet knowledge for

electronic searching of the literature

Case Study

• A 30-year-old female presents with recurrent Urinary tract infection for past 8 months; these episodes have been treated with several courses of antibiotics but keep recurring. She asks if recurrences can be prevented with antibiotics.

History 1980

• The researchers found that physicians were using very different standards to decide which patients required surgery.

• The variation rates of prostate surgery & hysterectomy of up to 300% between similar countries.

Definition Evidence based medicine could be defined as the science of integrating the best available

evidence from clinical research with physicians experience and patients' unique values and

preferences.(David Sackett and colleagues)

EBM Triads

Gordon Guyatt and colleagues from McMaster University (Canada) in 1992

The clinical question background vs. foreground

1- Background questions:

• Their answers are “fiber of medicine.”• Answers usually found in medical textbooks.

The clinical question background vs. foreground

2- Foreground questions • are those usually found at the cutting edge of

medicine.• They are questions about the most recent

therapies, diagnostic tests, or current theories of illness causation.

• These are the questions that are the heart of the practice of EBM.

Novice Expert

Background QuestionForeground

Question

Examples • Background questions:1- The causative microbiologic agent of disease.2- A recommended dose of a drug.3- A list of the attributes of syndrome.

• Foreground questions: 1- Intervention or exposure2- A possible comparison intervention3- Outcomes of interest.

The Traditional Method of Medical Practice

1. Knowledge2. Reading3. Experience4. Experts and peers opinions

Using the Medical Literature to Provide Optimal Patient Care

Using the Medical Literature to Provide Optimal Patient CareIdentify your problem.

↓Define a structured question.

↓Find the best evidence.

(original primary study or evidence summary)↓

How valid is the evidence?↓

What are the results?↓

How should I apply the results to patient care?

How to Practice

1- Asking clinical questions.

2- basic knowledge for electronic

searching of the literature.

3- application of critical appraisal

rules.

Scheme PICO

Search Terms

Search Strategy

Conclusion & References

1 -Asking

Examples • A 30-year-old female presents with recurrent Urinary

tract infection for past 8 months; these episodes have been treated with several courses of antibiotics but keep recurring. She asks if recurrences can be prevented using antibiotics.

• P = Female patient with recurrent UTI.• I = prophylactic AB.• C = No intervention.• O = No recurrence.

Examples • What is the duration of recovery for patients

with total hip replacement who developed a post-operative infection as opposed to those who did not within the first six weeks of recovery ?

PICO

• Patient: patients with total hip replacement.• Intervention: developed a post-operative

infection.• Comparison: opposed to those who did not.• Outcome: the duration of recovery.

Examples Jean 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 read quite a bit about this in the newspapers lately. She asks you if she would wear elastic stocking on her next trip to reduce her risk of this.

PICO

• P= 55 years Old woman.• I= elastic stocking.• C= no intervention.• O= prevention DVT risk in long trips.

Basic computer and internet knowledge for electronic searching of the literature

A Hierarchy of Preprocessed Evidence

The Haynes 5S, knowledge acquisition pyramid.

1 .Studies

• Selecting only those studies that are both highly relevant and characterized by study designs that minimize bias and thus permit a high strength of inference.

• Original or primary studies (eg, those stored in MEDLINE).

• Many studies exist but the information they contain needs evaluation before application to clinical problems.

2 .Systematic reviews (syntheses)• Reviews involving the identification, selection, appraisal, andsummary of primary studies addressing a focused clinical questionusing methods to reduce the likelihood of bias.

• The Cochrane Collaboration provides systematic reviews of health care interventions. You can also find systematic reviews in MEDLINE and other databases.

• By collecting the evidence on a topic, systematic reviews become more useful than individual or primary studies.

Systematic review VS meta-analysis

3 .Synopses • Brief summaries that encapsulate the key methodologic details

and results of a single study or systematic review.• Pre appraised resource journals and products such as ACP Journal

Club.

1- Initially, the articles act as an alerting service to keep physicians current on recent advances.

2- When rigorously and systematically assembled, the content of such resources becomes, over time, a database of important articles.

4 .Summaries & Systems

• Practice guidelines, clinical pathways, or evidence-based textbook summaries that integrate evidence-based information about specific clinical problems and provide regular updates to guide the care of individual patients.

Extract “Key Words”

Boolean operators“AND” “OR’’ “NOT’’

Boolean operators

• The basic Boolean logic operators for searching are: AND, OR and NOT

• These operators can be used to narrow or broaden searches

“AND’’

A B• narrow or broaden searches ??

’‘OR’’

A B• narrow or broaden

searches ??

’‘NOT’’

A B• narrow or broaden

searches ??

Try Boolean operators

Evidence Based Guidelines

National Guideline Clearinghouse

• A database of evidence-based clinical practice guidelines and related documents. It is maintained as a public resource by the Agency for Healthcare Research and Quality (AHRQ) of the U.S. Department of Health and Human Services.

• The database is updated weekly with new and revised guidelines. The currency of all guidelines is verified annually through NGC's Annual Verification process.

National GuidelineClearinghouse

The site features:• A Guideline Comparison utility that gives users the ability to

generate side-by-side comparisons.• Guideline Syntheses prepared by NGC staff, comparing guidelines

covering similar topics, highlighting areas of similarity and difference.

• An electronic forum, NGC-L for exchanging information on clinical practice guidelines, their development, implementation and use

• An Annotated Bibliography database where users can search for citations for publications and resources about guidelines, including guideline development and methodology, structure, evaluation, and implementation.

Clinical practice guidelines

illustrate that this classification (like any other)has its limitations: guidelines have aspects of systems and summaries, and sometimes of synopses.

National Guideline Clearinghouse

Use:

• Quotation marks “ “• Boolean operators (AND, OR, NOT)• Asterisk (*)

Scenario

• A 30-year-old female presents with recurrent Urinary tract infection for past 8 months; these episodes have been treated with several courses of antibiotics but keep recurring. She asks if recurrences can be prevented.

Scenario • 25 years old male

complaining from Chronic obstructive pulmonary disease (COPD) and the case was worsen last week, the patient visited the clinic for finding the best treatment modality.

Systematic Reviews

Cochrane Collaboration

• The Cochrane Collaboration is an independent nonprofit organization consisting of a group of more than 31,000 volunteers in more than 120 countries.

• The collaboration was formed to organize medical research information in a systematic way to facilitate the choices that health professionals, patients, policy makers and others face in health interventions according to the principles of evidence-based medicine.

Cochrane Collaboration• The Cochrane Collaboration

was founded in 1993 under the leadership of Iain Chalmers.

• It was developed in response to Archie Cochrane's call for up-to-date, systematic reviews of all relevant randomized controlled trials of health care.

THE COCHRANE LIBRARY

• Relies only on high quality randomized controlled trials for generating its evidence.

• Contains systematic reviews.

http://www.cochrane.orghttp://www.thecochranelibrary.com

THE COCHRANE LIBRARY

Database of Systematic Reviews Covers broad range of disciplines.

Authors' conclusions

• Continuous antibiotic prophylaxis for 6-12 months reduced the rate of UTI during prophylaxis when compared to placebo.

• After prophylaxis two studies showed no difference between groups. There were more adverse events in the antibiotic group.

• One RCT compared postictal versus continuous daily ciprofloxacin and found no significant difference in rates of UTIs, suggesting that postcoital treatment could be offered to woman who have UTI associated with sexual intercourse.

Studies

Cross-sectional Study

MEDLINE

(Indexing system)

www.pubmed.gov.

The Medline

• The Medline database represents the largest resource for non-appraised evidence all over the world.

• It contains over sixteen million abstract of scientific publications from about 480 medical journals in the USA, Europe and the rest of the world.

• It covers almost 40-50% of the worlds' scientific publications.

Filters

Send To

Saving

Clinical Queries

Clinical Queries

(Medical Subject Headings )MeSH

(Medical Subject Headings )MeSH

• MeSHis a list of controlled vocabulary generated by the U.S. National Library of Medicine (http://www.nlm.nih.gov/mesh/2002)to index abstracts of research papers published in the Pubmed.

• A subject heading search is a powerful tool for finding sets of only the most relevant records.

Scenario 22 years old male diagnosed with rhinosinusitis (RS), the physician prescribed an antibiotic for him and tolled him to come back after 10 days .. You remembered that you read something about the effectiveness of antibiotic treatment for acute RS.. You go to check this !!

PICO

Answer Q: what is the effectiveness of antibiotic treatment for acute RS ??

P = patient with acute RS ??I = AntibioticC= no antibiotic Outcome = Cure

Authors’ conclusion The potential benefit of antibiotics in the treatment of

clinically diagnosed acute rhinosinusitis needs to be seen in the context of a high prevalence of adverse events. Taking

into account antibiotic resistance and the very low incidence of serious complications, we conclude that there

is no place for antibiotics for the patient with clinically diagnosed, uncomplicated acute rhinosinusitis. This review cannot make recommendations for children, patients with

a suppressed immune system and patients with severe disease, as these populations were not included in the

available trials.

Conclusion

Among patients with acute rhinosinusitis, a 10-day course of amoxicillin compared with placebo did not reduce symptoms at day 3 of treatment.

THANK YOU