Why is retrieving “current best evidence” difficult?
Example Clinical Scenarios:
Diagnosis: How to select a diagnostic test or how to interpret the results of a particular test.
Therapy: Which treatment is the most effective, or what is an effective treatment given a particular condition.
Harm or Etiology: Are there harmful effects of a particular treatment, or how can these harmful effects be avoided.
Prognosis: What is the patient's likely course of disease, or how to screen for or reduce risk.
Define the clinical problem using the PICO components described above:
Now describe your own clinical scenario:
Create a PICO for the scenario –
Finding the best evidence in the literature
Online tools and databases where you find evidence-based resources can be divided into three categories:
1. Those that do most of the work for you
2. Those that do some of the work for you
3. Those where you do most of the work
But even when most of the work is done for you – you will still need to use your critical judgment!
1. Cochrane Database of Systematic Reviews (Cochrane Reviews) – rigorous, full-text reviews done by
Cochrane Review Groups with explicitly stated objectives and eligibility criteria, a comprehensive literature search, comparison of studies to criteria, justification of exclusions plus occasional updates
- Every Cochrane Systematic Review must have a standardized title including: Intervention / for a specific Problem / in a Patient Population (when appropriate)
- Every review goes through the following stages:
Title Review > Protocol Review > Protocol Publication > Review Development > Review Publication > Update > And sometimes, Withdraw
2. Database of Abstracts of Reviews of Effectiveness (DARE or Other Reviews) - systematic reviews published in journals and other, non-Cochrane sources, with quality assessed structured abstracts, produced by the Centre for Reviews and Dissemination (CRD) at the University of York, UK.
3. Cochrane Central Register of Controlled Trials (Clinical Trials) – journal citations of randomized trials, just under half are from MEDLINE, the remainder are from the European medical index EMBASE, as well as other published and unpublished sources, including Cochrane Groups Specialized Registers.
4. Cochrane Database of Methodology Reviews (Methods Reviews) – full-text systematic reviews on research methodological studies
5. Cochrane Methodology Register (Methods Studies) - citations on publications on how to conduct controlled trials and systematic reviews
6. Health Technology Assessment Database (Technology Assessments) – structured abstracts of studies on the medical, social, ethical and economic implications of health care interventions. Produced by the CRD.
7. NHS Economic Evaluation Database (Economic Evaluations) – structured abstracts of critically appraised economic evaluations of health care interventions, produced by the CRD.
8. About the Cochrane Collaboration (Cochrane Groups) – description of Cochrane Review Groups, Centres, etc.
- Updated quarterly.
- Individual subscription available
A1 might mean - a systematic review> where all included studies are RCTs with good follow up studying outcomes of clinical importance.
B2 might mean - a good quality non-random study that meets only one additional criteria – for example, the outcome is of clinical importance.
C3 might mean - consensus or other expert based information – which meets no criteria for study design.
Tips for retrieving EBM literature in Ovid MEDLINE, PubMed, and EMBASE:
· Use Clinical Trial publication types (pt) to limit your MEDLINE search to articles about actual clinical trials and to automatically explode all 7 clinical trial terms (below).
Clinical Trial.pt. (1991)
Clinical Trial, Phase I.pt. (1993)
Clinical Trial, Phase II.pt. (1993)
Clinical Trial, Phase III.pt. (1993)
Clinical Trial, Phase IV.pt. (1993)
Controlled Clinical Trial.pt. (1995)
Randomized Controlled Trial.pt. (1991)
Clinical Trials, the medical subject heading, retrieves articles on how to conduct clinical trials.
· Don’t limit your search to Review (pt). Reserve the Review limit for “quick ‘n dirty” searching. -Ann Intern Med 1999;131:947-951.
· Core Clinical Journals, also known as AIM (Abridged Index Medicus), limits your search to 120 clinical journals commonly found in hospital libraries. Use this limit for "quick ‘n dirty” searching only, and not EBHC searches.