Authors

Dr Paul Glasziou
Professor, Faculty of Health Sciences and Medicine
Bond University QLD 4229
Australia
Email: pglaszio@bond.edu.au

Introduction to evidence-based general practice

Using Evidence-based Medicine in General practice is perhaps more challenging but rewarding than in specialist medicine. The diversity of patient problems is much greater, but this also means a greater diversity of EBM resources is available. Many GPs are wary about applying the many studies done in non-GP settings. While the average GP patient is at lower risk or has lower pre-test probabilities of serious disease, the patho-biology of the patients is not usually different. Hence some thought about the effects of risk is required to apply results from other settings (Glasziou PP, Irwig L. An Evidence-based approach to individualising treatment, British Medical Journal, 1995; 311: 356-9.). In GP settings, the harms of therapy will outweigh the benefits more often than in the lower risk general practice population.

As Gill (P. Gill, AC. Dowell, RD. Neal, et al. Evidence based general practice: a retrospective study of interventions in one training practice. BMJ 312:819-821, 1996.) have demonstrated, evidence-based general practice is applicable to the majority of patient problems but the evidence appears less often to be the highest level for the question asked. The future of evidence-based general practice will require more attention to the methods of applicability of evidence and to special research tools such as the n-of-1 (single patient) trial, which help to accommodate the diversity of patients seen in the community.

Finally, the potential EBM practitioner should note that there is no conflict between a humanistic and patient centred approach to practice and the scientific rigor of EBM. Part of acting as a source of support and information for patients is a discussion and use of the best evidence.

Other resources for evidence-based general practice

Textbooks

Medical texts
Goroll, May & Mulley. Primary Care Medicine. Lippincott 1995.
This is a good (and reasonably evidence-based) problem-oriented textbook of ambulatory care problems. It generally deals with presentations (dyspnoea, hematuria, …) rather than specific diseases.
Diagnostic Strategies for Common Medical Problems( 2 ed). Black ER, Bordley DR, Tape TG, Panzer RJ(eds). ACP, Philadelphia, Pennsylvania, 1999
Available through: http://www.acponline.org. This provides a good summary of the value of diagnostic tests (including sensitivity and specificity) for and clinical approach to 52 common medical problems.
Guide to Clinical Preventive Services: Report of the U.S. Preventive Services Task Force. — 2nd ed. — Williams and Wilkins, 1996
This provides an excellent summary of the epidemiology and the potential effectiveness of screening in 176 clinical conditions. This is also available through the National Library of Medicine:http://text.nlm.nih.gov/
Clinical Evidence ’99. BMJ Publishing Group (due for release early in 1999).
This will provide a summary of the evidence of treatment effectiveness in most common clinical conditions.
Critical Appraisal and How-to texts

Sackett DL, Richardson WS, Rosenberg WMC, Haynes RB. Evidence-Based Medicine: How to Practice and Teach EBM, London:Churchill-Livingston, 1996.

The JAMA Series: Users’ Guides to the Medical Literature (Evidence Based Medicine Working Group.)
Electronic full text of articles in this series may be found at McMaster University http://jamaevidence.mhmedical.com/book.aspx?bookID=847

Internet Resources

PubMed Clinical Queries.
This is the National Library of Medicine’s free MEDLINE search site with the database pre-filtered for the best evidence for different types of clinical questions: diagnosis, treatment, aetiology, or…http://www.ncbi.nlm.nih.gov/pubmed/clinical/
Netting the Evidence: A ScHARR Introduction to Evidence Based Practice on the Internet
http://www.shef.ac.uk/scharr/ir/netting/. This site is a directory of other useful EBM sites, both general and content based.

Summary Journals

ACP Journal Club. American College of Physcians.

Evidence-based Medicine. BMJ Publishing Group.
Best Evidence: The purpose of Best Evidence is to alert clinicians to important advances in internal medicine, general and family practice, surgery, psychiatry, pediatrics, and obstetrics and gynecology by selecting from the biomedical literature those articles reporting studies and reviews whose results are most likely to be true and useful. These articles are summarized in value-added abstracts and commented on by clinical experts and first published in ACP Journal Club and Evidence-Based Medicine before amalgamation into Best Evidence. Details of subscriptions are found at the BMJ site: http://ebm.bmj.com/
Patient-Oriented Evidence that Matters (POEMs)
Developed by folk at the Journal of Family Practice, and compiled in InfoRetriever. Both available at their Website:http://www.infopoems.com/. Unfortunately, they do not give explicit criteria for the inclusion of particular studies, but do emphasise evidence that may make a difference to patients in general practice.

Other

Cochrane Library
The best single source of reliable evidence about the effects of health care in the world. If information relevant to your needs cannot be found in the Cochrane Database of Systematic Reviews , then you will often find relevant material in the Database of Abstracts of Reviews of Effectiveness . And if there are no relevant systematic reviews of research evidence yet available in either of these two databases, then you will almost always find relevant studies among the tens of thousands of records in the Cochrane Controlled Trials Register.
  • The Cochrane Database of Systematic Reviews (CDSR)
  • The Database of Abstracts of Reviews of Effectiveness (DARE)
  • The Cochrane Controlled Trials Register (CCTR)

Sample scenarios, searches, completed worksheets and CATs for evidence-based general practice

Choose one of the following scenarios: