Notes on Related Concepts: 'Bottom-up' EBP

The 'bottom-up' "Evidence Based Practice" paradigm first developed in McMaster University and the Centre for Evidence-Based Medicine, Oxford is relatively new to radiologists but is well established in several other specialities. There are 5 steps in applying this approach.

1. ASK - Information needs relevant to individual patients are converted into ‘answerable’ or ‘focused’ questions.

2. SEARCH - A comprehensive literature search is performed to find the best evidence to help answer these questions.

3. APPRAISE - The evidence must then be critically appraised, in an explicit and structured manner, in order to establish its validity, reliability and usefulness in practice.

4. APPLY - The results of this critical appraisal are then applied to the care of individuals or groups of patients.

5. EVALUATE - The clinical performance of the clinicians involved, using the principles derived from steps 1-4 above, are subjected to evaluation.

To effectively carry out step 3, literature is classified as belonging to one of several ‘domains.’ Examples of domains are Diagnosis, Therapy, Reviews, Clinical Guidelines, Prognosis, Economic Analysis and Qualitative research. The difference between ‘Evidence-Based’ and traditional, more freestyle ‘expert’ literature analysis is that these EBP researchers have described, in the peer-reviewed literature, an explicit process of appraisal for literature in each domain. Factors that will act as sources of bias in study design have been identified and weighted for effect. Mathematical analyses that will give the reader a clear idea of the strength, statistical significance and possible clinical significance of the results are described. Some of the ‘freestyle’ nature of ‘expert’ critical appraisal has been reined in.

'Bottom-up' EBP therefore follows the philosophy that "The aim of science is not to open a door to infinite wisdom, but to set a limit to infinite error " [1]. There is a lot of material available for those who wish to learn, practice or teaching the 'Bottom-up' Evidence-Based methods. It can be found in the original literature, [2], in textbook form [3-5] and on the Internet [6-10]. In particular, ‘Levels of Evidence’ have been defined that enable us to rapidly rank the likely validity of the information contained in research studies according to possible sources of bias in the study design [6]. The applicability of these principles to Radiology has been discussed in a perspective and a special review in Radiology [11, 12]. Interested readers are referred to these resources.

The McMaster / CEBM EBP principles were written by doctors, for doctors. Most practising radiologists who are willing to work for a few hours each week on their own continuing professional development should be able to make use of these principles. The approach taken in this website is partly based on the learning theory described in the link to ‘Problem-Based Learning’ – please read this section before you begin work in the EBP process section.

References

1. Brecht B, The Life of Galileo, ed. Manheim, JWaR. 1982, London: Methuen. 42.

2. Oxman AD, Sackett DL ,Guyatt GH, Users' guides to the medical literature. I. How to get started. The Evidence-Based Medicine Working Group. JAMA 1993; 270 (17):2093-2095. [ link ]

3. Evidence Based Medicine: How to Practice and Teach EBM. Sackett DL, Strauss SE, Richardson WS, Rosenberg W ,Haynes RB, 2nd ed 2000; 3rd ed. 2005, Edinburgh: Churchill Livingstone. [ link ]

4. Users' Guides to the Medical Literature: A Manual for Evidence-Based Clinical Practice. Eds. Guyatt G, Rennie D. 2002. JAMA and Archives Journals (AMA Press). [ link ]

5. Key Topics in Evidence-Based Medicine. McGovern DPB, Valori RM, Summerskill WSM, Levi M. 2001. Oxford: BIOS Scientific Publishers Ltd. [ link]

6. Centre for Evidence Based Medicine. Oxford University, Levels of Evidence and Grades of Recommendations. [ link ]

7. Health Information Research Unit (HIRU): Evidence-Based Health Informatics. McMaster University, Hamilton, Ontario, Canada. [ link ]

8. The Centre for Evidence-Based Medicine, University Hospital Network, University of Toronto, Canada.
[ link ]

9. User's Guides to the Medical Literature. McMaster University, A Manual for Evidence-Based Practice. [ link ]

10. User's Guides to Evidence-Based Practice. Centre for Health Evidence, University of Alberta, Canada.
[ link ].

11. Wood BP, What's the evidence? Radiology 1999; 213 (3):635-637.
[ link ]

12. Evidence-based radiology: a new approach to the practice of radiology. Radiology 2001; 220 (3):566-575. [ link ]