Date post: | 23-Jan-2015 |
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Using EBM to Answer Clinical Queries
Robin FeatherstoneClinical Medicine [email protected]://www.slideshare.net/featherr
Agenda
• Background vs. Foreground questions• Clinical evidence • Study types • Searching exercises
– Using PICO to refine questions– Searching down the levels of evidence
• Questions
EBM REFRESHER
Two Broad Question Categories
• Background = basic information about a subject
What is strabismus? What is a screening test for strabismus?
• Foreground = specific to a clinical scenarioIs Botulinum Toxin (Botox) more effective than surgery to improve cosmetic appearance for a patient with advanced strabismus?
Sources for Background Questions
Resource ExampleTextbook Robbins basic pathologyHandbook Adolescent medicine: a handbook for
primary careManual The Washington manual of surgeryEncyclopaedia Encyclopedia of respiratory medicineDictionaries Dorland’s pocket medical dictionary
Refine Foreground Questions using PICO
P = Patient or ProblemI = Intervention or ExposureC = ComparisonO = Outcomes
Determine your Question Type1,2
1. Aetiology: What is the cause of the disease and its mode of operation?
2. Diagnosis: How accurate is this diagnostic test?3. Prognosis: What is the probable course of the disease?4. Therapy: Is one intervention more effective than
another?5. Prevention: How to reduce the risk of this disease?6. Cost-effectiveness: Is one intervention more cost-
effective than another?7. Quality of life: What will be the patient’s quality of life?
1 Heneghan, Carl, and Douglas Badenoch. Evidence-Based Medicine Toolkit. 2nd ed. Malden, Mass.: BMJ Books/Blackwell Pub., 2006.2 Glover, Jan, and Lei Wang. Find it Fast: The Clinical Question : www.med.yale.edu/library/education/guides/screencasts/finditfast/finditfast_2/
Studies to Answer Each Type1,2
Type of Question Type of Evidence
Aetiology •Randomized controlled trials•Case-control or cohort studies•Case series
Diagnosis •Diagnostic validation studies•Prospective studies / blind comparison to a gold standard
Prognosis •Inception cohort studies•Case control studies•Case series
Therapy •Randomized controlled trials•Systematic reviews / meta-analyses
Prevention •Randomizes controlled trials•Cohort studies, case control studies•Systematic reviews / meta-analyses
Cost-effectiveness •Economic analyses
Quality of life •Qualitative studies1 Heneghan, Carl, and Douglas Badenoch. Evidence-Based Medicine Toolkit. 2nd ed. Malden, Mass.: BMJ Books/Blackwell Pub., 2006.2 Glover, Jan, and Lei Wang. Find it Fast: The Clinical Question : www.med.yale.edu/library/education/guides/screencasts/finditfast/finditfast_2/
Level of Evidence Pyramid
Qualitative Studies
CASE STUDIES AND SEARCHING EXERCISES
Case study 1
Refine this case into a question and identify the best study type to answer that question.
Your patient travels regularly on business and suffers frequently from the effects of jet lag. They’ve tried tomato juice and exercise but neither seems to help. They ask if there is anything else they can do?
Create an answerable question
Patient, Problem, or Population
Jet lag
Intervention
Comparison
Outcome(s) Reduced symptoms
What are the most clinically effective preventative measures for reducing the symptoms of jet lag?
Identify your question typeType of Question Type of Evidence
Aetiology •Randomized controlled trials•Case-control or cohort studies•Case series
Diagnosis •Diagnostic validation studies•Prospective studies / blind comparison to a gold standard
Prognosis •Inception cohort studies•Case control studies•Case series
Therapy •Randomized controlled trials•Systematic reviews / meta-analyses
Prevention •Randomizes controlled trials•Cohort studies, case control studies•Systematic reviews / meta-analyses
Cost-effectiveness •Economic analyses
Quality of life •Qualitative studies1 Heneghan, Carl, and Douglas Badenoch. Evidence-Based Medicine Toolkit. 2nd ed. Malden, Mass.: BMJ Books/Blackwell Pub., 2006.2 Glover, Jan, and Lei Wang. Find it Fast: The Clinical Question : www.med.yale.edu/library/education/guides/screencasts/finditfast/finditfast_2/
Select a resource
Qualitative Studies
Exercise
Select one of the following resources to answer the question: What are the most effective preventative measures for jet lag?
1. Cochrane Library2. ACP’s PIER3. PubMed4. Google Scholar
Conclusions
• Number of results
Source Hits
Cochrane Library 2
ACP’s PIER 43
PubMed 561 (56 if using MeSH with prevention subheading)
Google Scholar About 78,300
Discussion
• How does the quality of these results compare?
• Which resource would you use in a clinical setting? In a research setting?
Case Study 2
A patient with breast cancer asks how women typically feel after mastectomy. How will her life differ after surgery?
What step should we take first to answer this question?
Create an answerable question
Patient, Problem, or Population
Patients following mastectomy
Intervention
Comparison
Outcome(s) Quality of life
What is the quality of life of patients following mastectomy?
Identify your question typeType of Question Type of Evidence
Aetiology •Randomized controlled trials•Case-control or cohort studies•Case series
Diagnosis •Diagnostic validation studies•Prospective studies blind comparison to a gold standard
Prognosis •Inception cohort studies•Case control studies•Case series
Therapy •Randomized controlled trials•Systematic reviews / meta-analyses
Prevention •Randomizes controlled trials•Cohort studies, case control studies•Systematic reviews / meta-analyses
Cost-effectiveness •Economic analyses
Quality of life •Qualitative studies1 Heneghan, Carl, and Douglas Badenoch. Evidence-Based Medicine Toolkit. 2nd ed. Malden, Mass.: BMJ Books/Blackwell Pub., 2006.2 Glover, Jan, and Lei Wang. Find it Fast: The Clinical Question : www.med.yale.edu/library/education/guides/screencasts/finditfast/finditfast_2/
Select a resource
Qualitative Studies
Exercise
Search the following resources to answer the question: What is the quality of life of patients following mastectomy?
1. PsycINFO2. CINAHL3. Google Scholar
Conclusions
• Number of results
Source Hits
PsycINFO 10
CINAHL 92
Google Scholar about 21,900
Discussion
• How do qualitative questions compare to other question types?
• How do you assess the quality of these results?
Case Study 3
A patient expresses concern before cataract surgery about the amount of pain they will experience. You consider administering intracameral anaesthetic (lidocaine) as a supplement to topical anaesthetic, but you’re not sure if the additional anaesthesia will reduce intraoperative pain perception compared with topical anaesthetic alone.
Create an answerable question
Patient, Problem, or Population
Intervention
Comparison
Outcome(s)
Create an answerable question
Patient, Problem, or Population
Patients undergoing cataract surgery
Intervention Topic anaesthesia alone
Comparison Topical anaesthesia with intracameral lidocaine
Outcome(s) Reduction of pain perception
In cataract surgery patients, does topical anaesthetic alone reduce pain perception when compared to topical anaesthetic supplemented by intracameral lidocaine?
What kind of question is this?
Type of Question Type of Evidence
Aetiology •Randomized controlled trials•Case-control or cohort studies•Case series
Diagnosis •Diagnostic validation studies•Prospective studies blind comparison to a gold standard
Prognosis •Inception cohort studies•Case control studies•Case series
Therapy •Randomized controlled trials•Systematic reviews / meta-analyses
Prevention •Randomizes controlled trials•Cohort studies, case control studies•Systematic reviews / meta-analyses
Cost-effectiveness •Economic analyses
Quality of life •Qualitative studies1 Heneghan, Carl, and Douglas Badenoch. Evidence-Based Medicine Toolkit. 2nd ed. Malden, Mass.: BMJ Books/Blackwell Pub., 2006.2 Glover, Jan, and Lei Wang. Find it Fast: The Clinical Question : www.med.yale.edu/library/education/guides/screencasts/finditfast/finditfast_2/
Select a resource
Exercise
Search whatever resource you think would best answer the question:
In cataract surgery patients, does topical anaesthetic alone reduce pain perception when compared to topical anaesthetic supplemented by intracameral lidocaine?
Results
• What resources did you search? • Did you find the answer to your question?
Summary
• Background vs. Foreground questions• Using PICO to formulate an answerable
question • Identifying question types• Identifying studies that best answer your
question• Searching down the levels of evidence
QUESTIONS?