Ongoing EBR - Getting Research into Practice

The basic principles underlying the ‘evidence-based’ practice movement are that there is a hierarchy of evidence and that modern informatics can make the evidence available to practitioners at the point of care. Time limitation remains the biggest obstacle to evidence-based practice. Clinicians should seek evidence from as high in the appropriate hierarchy of evidence as possible [1]. In Medicine, much effort has gone into the analysis and synthesis of reliable reviews of the literature. This has not yet been done in Radiology. Whether you are looking for information to help you finish a report or want to do a detailed evaluation of a topic the following principles can be applied to Diagnostic Radiology. In reverse order of comprehensiveness, the evidence you create using the EBM methods can be roughly ranked as:

‘Single Search’ Evidence: The results of a single literature search, to fill a ‘knowledge gap’ identified during a reporting session or clinico-radiologic conference. Although a single search may miss some of the relevant literature, you may well find enough to answer the key question. The ‘SEARCH’ section of this website gives details of how to do this type of searching.

‘Critically Appraised Topics’ or CATs are an EBM tool for teaching and learning. This is a structured, one-page summary of the results of an evidence-based learning effort in which a patient’s illness stimulates a learner’s question, for which the learner finds evidence, appraises it critically and decides whether and how to use that evidence in the care of the patient. A CAT is a summary of such work by practicing clinicians, using the best available evidence and in ‘real time’ everyday searching. A CAT is also designed to reflect the pragmatics of using the evidence in a particular setting. More information on CATs can be found at the Oxford website [2]. Some collections of CATS are listed below under CAT links. There are no Radiology CAT banks as yet. Let us know if you find one that we can link to!

CAT Links

You can download PDF examples of CATs produced by the SVUH radiology EBP group on the relative roles of US and CT in blunt abdominal trauma; imaging intestinal ischemia; and assessing whether small bowel obstruction is likely to resolve spontaneously by clicking on the hyperlinks in this sentence.

Some collections of CATS can be reviewed at the Bioinformatics 'CAT Crawler.' There are no Radiology CAT banks as yet. Let us know if you find one that we can link to!

REVIEWS

Expert Reviews: The traditional ‘expert’ review can suffer from several biases. The ‘expert’ may not have identified all the literature. They may be primary investigators with a point to prove, rather than being engaged in a process of sifting all the evidence and letting the cards fall as they will (investigator bias).

Evidence-Based Reviews: The next most reliable reviews are those in which the authors have used EBM guidelines [3] but have in some way restricted their search. For example, the English literature only may have been searched, only computer searching may have been used etc.. Analysis of retrieved articles has been done using EBM methodology and conclusions are (within the limitations of the search) as free from bias as possible. We have conducted several such ‘Evidence Based Radiology’ reviews. We have found them helpful in defining local practice policies and recommend them as a strategy for radiologists. They are the results of more comprehensive searching than a typical CAT and should be more reliable. Members of this group have published several such reviews in the Radiology literature. The topics were Endovascular Repair of Abdominal Aortic aneurysms [EVAR](2003), Trans-arterial chemo-embolization [TACE] of hepatocellular carcinoma (2005) and the role of positron emission tomography (PET) scanning in the pre-operative assessment of patients with colorectal liver metastases (2007).

Systematic Reviews: A systematic review is the most reliable form of review. It is one that uses explicit methods, designed to limit bias, to identify, select and critically appraise relevant research on a subject [3]. In these, the authors have attempted to identify all relevant information (including unpublished material, theses, etc.) using computer and hand searching. Systematic reviews include, but are not restricted to, reviews using advanced statistical methods for pooled data analysis, such as meta-analysis. These are increasingly becoming available for radiology topics. The ‘User’s Guide’ to review articles will help you evaluate any published review [3]. Some systematic reviews use ‘meta-analysis’ (a sophisticated statistical technique) to extract reliable data by pooling many smaller studies. [4] Halligan and Altman (Radiology 2007) summarise clearly the key properties of systematic reviews and meta-analyses [5].

References

1. Guyatt GH, Haynes RB, Jaeschke RZ, et al., Users' Guides to the Medical Literature: XXV. Evidence-based medicine: principles for applying the Users' Guides to patient care. Evidence- Based Medicine Working Group. Jama 2000; 284 (10):1290-1296. [ link ]

2. The NHS Research and Development Centre for Evidence-Based Medicine, Oxford. December 17, 2007. [ link ]

3. Oxman AD, Cook DJ ,Guyatt GH, Users' guides to the medical literature. VI. How to use an overview. Evidence-Based Medicine Working Group. JAMA 1994; 272 (17):1367-1371. [ link ]

4. Muradin G BJ, Stijnen T, Hunink MG., Balloon Dilation and Stent Implantation for Treatment of Femoropopliteal Arterial Disease: Meta-Analysis. Radiology 2001; 221 :137-145. [ link ]

5. Halligan S, Altman DB. Evidence-Based Practice in Radiology: Steps 3 and 4 - Appraise and Apply Systematic Reviews and Meta-Analyses. Radiology 2007; 243:13-27.[ link PDF (ebr.07.pdf) ]