How to Write a Critically Appraised Topic (CAT)

Medical knowledge and the volume of scientific articles published have expanded rapidly over the past 50 years. Evidence-based practice (EBP) has developed to help health practitioners get more benefit from the increasing volume of information to solve complex health problems. A format for sharing information in EBP is the critically appraised topic (CAT). A CAT is a standardized summary of research evidence organized around a clinical question, aimed at providing both a critique of the research and a statement of the clinical relevance of results. In this review, we explain the five steps involved in writing a CAT for a clinical purpose (“Ask,” “Search,” “Appraise,” “Apply,” and “Evaluate”) and introduce some of the useful electronic resources available to help in creating CATs.

Medical knowledge has expanded rapidly over the past 50 years. Many subcategories of disease, diagnostic testing, and treatment strategies are now known. Paralleling this improvement in medicine, the volume of scientific articles published has exploded and is doubling every 10 years . Therefore, evidence-based practice (EBP) and publications in this area have developed to help health practitioners keep up to date with the increasing volume of information to solve complex health problems .

One of the main formats for sharing information in EBP is the critically appraised topic (CAT). A CAT is a standardized summary of research evidence organized around a clinical question, aimed at providing both a critique of the research and a statement of the clinical relevance of results . In other words, CATs are not just abstracts of existing evidence. They critique the internal validity, external validity (generalizability), and statistical rigor (or methodology) of the best research evidence to date and summarize the results into a few pages . In contrast to systematic reviews, which are written by content and methodology experts, CATs may be more easily written by clinicians and practitioners . Critically appraised topics provide easy access to the scientific literature for clinicians who are either too busy to pursue the answer to a clinical problem among the mixed results from a search engine or do not have the specialized skill to critically appraise the literature and reach an appropriate conclusion . The main reason to produce a CAT is to answer an explicit clinical question arising from a specific patient encounter, and is the essence of EBP in that a health professional generates a clinical question from a real clinical situation, followed by finding and appraising the evidence, and finally applying it in clinical practice .

In this review, we start by explaining the steps involved in writing a CAT for a clinical purpose and introduce some of the available electronic CAT makers.

How to write a CAT?

Writing a CAT involves five steps along the five steps of evidence-based practice which can be summarized as “Ask,” “Search,” “Appraise,” “Apply,” and “Evaluate” . These steps are:

1. Asking a focused and answerable question that translates uncertainty to an answerable question
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Step 1: Ask an Answerable Question

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Table 1

Examples of CAT Questions in PICO Format

CAT Study Question PICO Format Question Patient or Problem Intervention Comparison Intervention Outcome Whether low-dose CTC would perform as well as optical colonoscopy for screening patients for CRC? Is low-dose CTC equivalent to optical colonoscopy in identifying >5-mm colonic polyps? Screening population of patients with polyps CTC Optical colonoscopy Accuracy in diagnosis of >5-mm colonic polyps/colorectal cancer Whether ultrasound performs better than MRI in the diagnosis of rotator cuff tears? In patients with rotator cuff tears, how does US compare to MRI for diagnosis? Patients with rotator cuff tear US MRI Accuracy in diagnosis of rotator cuff tears Whether coronary CTA performs comparably to invasive coronary angiography for identifying potentially or probably hemodynamically significant native coronary artery disease, defined as luminal diameter stenosis of at least 50%? In patients with known or suspected coronary artery disease, how does coronary CTA compare with invasive coronary angiography for identifying ≥50% luminal diameter coronary artery stenosis? Patients with known or suspected coronary artery disease Coronary CTA Catheter coronary angiography Accuracy in diagnosis of ≥50% luminal diameter coronary artery stenosis How does CTA perform in comparison with MRA in the detection of symptomatic carotid stenosis? In patients with symptomatic carotid stenosis, how does CTA compare to MRA for diagnosis? Patients with symptomatic carotid artery stenosis Carotid CTA Carotid MR angiography Accuracy in diagnosis of carotid artery stenosis What is the current role of RFA and how does RFA compare to surgical resection for treatment of colorectal liver metastases? In patients with colorectal liver metastases how does percutaneous RFA compare with surgical resection or other ablative techniques? Patients with colorectal liver metastasis Percutaneous RFA Surgical resection Annual recurrence or mortality rate

CAT, critically appraised topic; CRC, colorectal carcinoma; CTA, computed tomography angiography; CTC, computed tomography colonography; MRA, magnetic resonance angiography; MRI, magnetic resonance imaging; PICO, patient or problem, intervention, comparison intervention, outcome; RFA, radiofrequency ablation; US, ultrasound.

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Step 2: Search for the Best Current Evidence

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Table 2

Examples of Search Strategies for the PICO of Questions

PICO Format Question Patient or Problem Intervention Comparison Intervention Outcome Is low-dose CT colonography equivalent to optical colonoscopy in identifying clinically meaningful colonic polyps? Polyp

colorectal neoplasm

colonic neoplasmand CT colonography

colonography, computed tomographic

and

low-doseand Colonoscopyand Diagnosis

or sensitivity and specificity In patients with rotator cuff tears, how does US compare to MRI for diagnosis? Rotator cuff

shoulder

tendon

injury

pathologyand Ultrasonography

USand Magnetic resonance imaging

MRI

contrast-enhanced MRIand Diagnosis

sensitivity and specificity In patients with known or suspected coronary artery disease, how does coronary CT angiography compare to invasive coronary angiography for identifying ≥50% luminal diameter coronary artery stenosis? Coronary artery diseaseand Tomography, x-ray computed

tomography, x-ray computed/methodsand Angiography

coronary angiography

coronary angiography methodsand Coronary stenosis

diagnosis

sensitivity and specificity In patients with symptomatic carotid stenosis, how does CTA compare with MRA for diagnosis? Carotid artery stenosisand Tomography, x-ray computed

tomography, x-ray computed/methodsand MRI/MRA

MRI

contrast-enhanced MRIand Diagnosis

sensitivity and specificity In patients with colorectal liver metastases how does percutaneous radiofrequency ablation compare with surgical resection or other ablative techniques? “Liver neoplasm”

“liver neoplasm/secondary”and Catheter ablationand Liver neoplasm/surgeryand Efficacy

recurrence

mortality

CT, computed tomography; MRA, magnetic resonance angiography; MRI, magnetic resonance imaging; US, ultrasound.

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Primary study designs

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Levels of evidence

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Table 3

Designation of Levels of Evidence According to Type of Research

This table is adapted from the Oxford Centre for Evidence Based Medicine Website .

Level Etiology Diagnosis Intervention Prognosis Ia Systematic review with homogeneity ∗ of Level Ib studies Systematic review with homogeneity ∗ of Level Ib studies Systematic review with homogeneity ∗ of Level Ib studies Systematic review with homogeneity ∗ of Level Ib studies Ib Randomized controlled trial Validating † cohort study with good ‡ reference standard Randomized controlled trial Cohort study with good (>80%) follow-up Ic Absolute SP-ins and SN-outs § IIa Systematic review with homogeneity ∗ of Level IIb studies Systematic review with homogeneity ∗ of Level IIb studies Systematic review with homogeneity ∗ of Level IIb studies Systematic review with homogeneity ∗ of Level IIb studies IIb Cohort study (prospective) Exploratory † cohort study with good ‡ reference standard Cohort study (prospective) Cohort study (retrospective) IIc Outcomes research Outcomes research Outcomes research Outcomes research IIIa Systematic review with homogeneity ∗ x of nonconsecutive cohort or case control studies Systematic review with homogeneity ∗ of Level IIIb studies Systematic review with homogeneity ∗ of case control studies Systematic review with homogeneity ∗ of case control studies IIIb Nonconsecutive cohort study or case control study Nonconsecutive studies; or without consistently applied reference standard Case control study IV Poor-quality || cohort study or poor quality case control study or case series Case series or poor or nonindependent reference standard Poor-quality || cohort study or poor quality case control study or case series Poor-quality || cohort study or poor quality case control study or case series V “Expert” opinion without critical appraisal “Expert” opinion without critical appraisal “Expert” opinion without critical appraisal “Expert” opinion without critical appraisal

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The evidence pyramid

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Sources of evidence for primary literature

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Sources of evidence for secondary literature

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Step 3: Appraise the Literature

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Critically appraising primary literature

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Interpreting results in diagnostic radiology

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Table 4

Statistical Measures for Diagnostic and Therapeutic Literature

Measure Meaning Interpretation Diagnostic literature Sensitivity Patients with the disease with positive test results (“true positives”)/patients with disease Negative test result in a highly sensitive test can rule out the disease if prevalence is relatively low Specificity Patients without the disease with negative results (“true negatives”)/well people (no disease) Positive test result in a highly specific test can rule in the disease if prevalence is relatively high Positive predictive value (PPV) Patient with true positive test results/all patients with positive test result (true positives + false positives) This value is affected by the prevalence in the population studied. If a test has a high PPV (>95%) in your population, one may confidently commence treatment Negative predictive value (NPV) Patients with true negative results/all patients with negative test result (true negatives + false negatives) This value is affected by the prevalence in the population studied. If a test has a high NPV (>95%) in your population, one May be able to safely withhold treatment Likelihood ratio (LR) Likelihood of a given test result in patients with disease/the likelihood of the same result in patients without disease LR = 0 (negative LR): excludes the disease

LR = infinity (positive LR): confirms the disease

LR = 1 the test result is uninformative as the result is equally likely in the two groups Therapeutic literature Relative risk (RR) Risk of developing disease (or outcome) in the treatment group/risk of developing disease (or outcome) in the control group RR = 1: no difference between groups

RR <1 treatment reduces the risk of the disease

RR >1 treatment increases the risk of the disease Absolute risk (AR) Difference in the rates of events calculated as the rate in the control group minus the rate in the experimental group AR = 0 no difference between groups

AR positive: treatment is beneficial

AR negative: treatment is harmful Number needed to treat The number of patients needed to be treated for one of them to benefit from the treatment Number needed to harm The number of patients needed to be treated for 1 patient to experience an adverse effect

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Statistical measures for therapeutic studies

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Critically appraising secondary literature

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Results of a meta-analysis

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Summarizing the results of your literature review

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Step 4: Apply

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Step 5: Evaluate

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Helpful tools

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Table 5

Helpful Web Sites

Name Link PubMed, US National Library of Medicine, and National Institutes of Health http://www.ncbi.nlm.nih.gov/sites/entrez Medline/Ovid SP http://gateway.ovid.com/ EMBASE http://www.embase.com/ Google Scholar http://scholar.google.com/ ISI Web of Knowledge http://apps.isiknowledge.com/UA_GeneralSearch_input.do?product=UA&search_mode=GeneralSearch&SID=4BKm4mOcfDnofbKjHBI&preferencesSaved= MD Consult http://www.mdconsult.com/php/120885574–2/homepage Cochrane Collaboration http://www.cochrane.org The Cumulative Index to Nursing and Allied Health Literature http://www.ebscohost.com/cinahl/ National Institute of Clinical Excellence http://www.nice.org.uk/ Scottish Intercollegiate Guidelines Network http://www.sign.ac.uk/ SUMSearch search engine http://sumsearch.uthscsa.edu/ The National Library for Health http://www.library.nhs.uk/Default.aspx National Guidelines Clearinghouse http://www.guideline.gov/ PubMed Clinical Queries http://www.ncbi.nlm.nih.gov/entrez/query/static/clinical.shtml The American College of Physicians Journal Club http://www.acpjc.org/ BMJ Evidence Based Medicine http://ebm.bmj.com/ Bandolier electronic journal http://www.medicine.ox.ac.uk/bandolier/aboutus.html The Turning Research Into Practice Database http://www.tripdatabase.com/index.html UpToDate http://www.uptodate.com/home/index.html Dynamed Clinical Reference Tool http://www.ebscohost.com/dynamed/ Physicians Information and Education Resource http://pier.acponline.org/index.html BMJ Clinical Evidence http://clinicalevidence.bmj.com/ceweb/index.jsp The Database of Abstracts of Reviews of Effects http://mrw.interscience.wiley.com/cochrane/cochrane_cldare_articles_fs.html The Cochrane Central Register of Controlled Clinical Trials (CENTRAL) http://www.mrw.interscience.wiley.com/cochrane/cochrane_clcentral_articles_fs.html The National Library of Medicine http://www.nlm.nih.gov/ Netting the Evidence http://www.shef.ac.uk/scharr/ir/netting/ The Center for Evidence Based Radiology at the Brigham and Women’s hospital http://www.brighamandwomens.org/cebi/default.aspx Centre for Reviews and Dissemination at the University of York http://www.york.ac.uk/inst/crd/ The Centre for Health Evidence at the University of Alberta http://www.cche.net/ The Centre for Evidence Based Medicine at Oxford http://www.cebm.net/ The Centre for Evidence Based Medicine at the University Health Network, Toronto http://www.cebm.utoronto.ca/practise/evaluate/index.htm#top The Blue Cross and Blue Shield Association Technology Evaluation Center http://www.bcbs.com/blueresources/tec/ BestBETs Best Evidence Topics http://www.bestbets.org/ CAT crawler http://www.bii.a-star.edu.sg/achievements/applications/catcrawler/cat_search.asp Centre for Evidence Based Radiology http://www.evidencebasedradiology.net

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Good secondary sources

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Good primary sources

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CATmaker

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Using CATs to teach evidence-based medicine/imaging

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Conclusion

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Acknowledgment

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Supplementary Data

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Appendix Table 1

Appendix Table 2

Appendix Table 3

Appendix Table 4

Appendix Table 5

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References

1. Dawes M.: Critically appraised topics and evidence-based medicine journals. Singapore Med J 2005; 46: pp. 442-448. quiz 449
2. Fetters L., Figueiredo E.M., Keane-Miller D., et. al.: Critically appraised topics. Pediatr Phys Ther 2004; 16: pp. 19-21.
3. Wendt O. Developing critically appraised topics (CATs). Presented at the American speech-language hearing association, division 12: augmentative and alternative communication (DAAC), 7th annual conference, San Antonio, January 2006. Available at: http://www.edst.purdue.edu/aac/Developing%20Critically%20Appraised%20Topics.pdf . Accessed May 3, 2010.
4. Dawes M., Summerskill W., Glasziou P., et. al.: Sicily statement on evidence-based practice. BMC Med Educ 2005; 5: pp. 1.
5. Glasziou P., Salisbury J.: EBP step 1: formulate an answerable question. Evidence based practice workbook, 2nd ed.2007.Blackwell PublishingMalden, MA p. 21–38
6. Staunton M.: Evidence-based radiology: steps 1 and 2—asking answerable questions and searching for evidence. Radiology 2007; 242: pp. 23-31.
7. Feussner J.R., Matchar D.B.: When and how to study the carotid arteries. Ann Intern Med 1988; 109: pp. 805-818.
8. Kelly A.M.: Evidence-based radiology: step 1—ask. Semin Roentgenol 2009; 44: pp. 140-146.
9. McGrane S., McSweeney S.E., Maher M.M.: Which patients will benefit from percutaneous radiofrequency ablation of colorectal liver metastases? Critically appraised topic. Abdom Imaging 2008; 33: pp. 48-53.
10. Kelly A.M., Fessell D.: Ultrasound compared with magnetic resonance imaging for the diagnosis of rotator cuff tears: a critically appraised topic. Semin Roentgenol 2009; 44: pp. 196-200.
11. El-Maraghi R.H., Kielar A.Z.: CT colonography versus optical colonoscopy for screening asymptomatic patients for colorectal cancer a patient, intervention, comparison, outcome (PICO) analysis. Acad Radiol 2009; 16: pp. 564-571.
12. El-Maraghi R., Kielar A.: Low-dose computed tomographic colonography versus optical colonoscopy: a critically appraised topic. Semin Roentgenol 2009; 44: pp. 191-195.
13. Czum J.M.: Coronary CT angiography for coronary artery stenosis: a critically appraised topic. Semin Roentgenol 2009; 44: pp. 188-190.
14. Petrou M., Foerster B.R.: Relative roles of magnetic resonance angiography and computed tomographic angiography in evaluation of symptomatic carotid stenosis: a critically appraised topic. Semin Roentgenol 2009; 44: pp. 184-187.
15. Meinert C.L.: An insider’s guide to clinical trials.2011.Oxford University PressOxford, UK
16. Friedman L.M., Furberg C., DeMets D.L.: Fundamentals of clinical trials.1998.BirkhäuserBasel, Switzerland
17. Piantadosi S.: Clinical trials: a methodologic perspective.2005.John Wiley and SonsHoboken, NJ
18. Rosenbaum P.R.: Observational studies.2002.SpringerBerlin, Germany
19. Schlesselman J.J., Stolley P.D.: Case-control studies: design, conduct, analysis.1982.Oxford University PressOxford, UK
20. Breslow N.E., Day N.E.: Statistical methods in cancer research. Volume I - the analysis of case-control studies.1980.IARC Sci PublLyon, France p. 5–338
21. Levels of evidence. Oxford Center for Evidence-Based Medicine Web site. http://www.cebm.net/index.aspx?o=1025 . Accessed May 3, 2010.
22. Haynes R.B.: Of studies, summaries, synopses, and systems: the “4S” evolution of services for finding current best evidence. Evid Based Ment Health 2001; 4: pp. 37-39.
23. Haynes R.B.: Of studies, summaries, synopses, and systems: the “4S” evolution of services for finding current best evidence. Evid Based Nurs 2005; 8: pp. 4-6.
24. Haynes B.: Of studies, syntheses, synopses, summaries, and systems: the “5S” evolution of information services for evidence-based healthcare decisions. Evid Based Nurs 2007; 10: pp. 6-7.
25. Dicenso A., Bayley L., Haynes R.B.: Accessing pre-appraised evidence: fine-tuning the 5S model into a 6S model. Evid Based Nurs 2009; 12: pp. 99-101.
26. The Centre for Evidence Based Medicine at Oxford website. http://www.cebm.net/index.aspx?o=1016 . Accessed on July 23, 2010.
27. NCBI Pubmed Web site. US National Library of Medicine. http://www.ncbi.nlm.nih.gov/PubMed . Accessed May 3, 2010.
28. EMBASE. EMBASE Biomedical Answers website. http://www.embase.com/home . Accessed May 3, 2010.
29. ISI Web of Knowledge website. www.isiknowledge.com . Accessed May 3, 2010.
30. MD Consult website. www.mdconsult.com . Accessed May 3, 2010.
31. Google Scholar Beta. Google website. http://scholar.google.com . Accessed May 3, 2010.
32. Kelly A.M.: Evidence-based radiology: step 2—searching the literature (search). Semin Roentgenol 2009; 44: pp. 147-152.
33. The Cochrane Collaboration website. http://www.cochrane.org . Accessed May 3, 2010.
34. TRIP database. http://www.tripdatabase.com . Accessed May 3, 2010.
35. NICE. National Institute for Health and Clinical Excellence website. http://www.nice.org.uk . Accessed May 3, 2010.
36. SUMSearch. University of Texas Health Science Center at San Antonio website. http://sumsearch.uthscsa.edu . Accessed May 3, 2010.
37. CINAHL. Cumulative Index to Nursing and Allied Health Literature website. http://www.ebscohost.com/cinahl . Accessed May 3, 2010.
38. National Guidelines Clearinghouse. http://www.guideline.gov . Accessed May 3, 2010.
39. The National Library for Health. www.library.nhs.uk . Accessed May 3, 2010.
40. SIGN. Scottish Intercollegiate Guidelines Network. http://www.sign.ac.uk . Accessed May 3, 2010.
41. American College of Physicians Journal Club website. http://www.acpjc.org . Accessed May 3, 2010.
42. Evidence-Based Medicine Online website. BMJ Publishing Group. http://ebm.bmj.com . Accessed May 3, 2010.
43. Clinical Evidence website. BMJ Publishing Group. http://clinicalevidence.bmj.com/ceweb/index.jsp . Accessed May 3, 2010.
44. Up to Date website. http://www.uptodate.com/home/index.html . Accessed May 3, 2010.
45. Bossuyt P.M., Reitsma J.B., Bruns D.E., et. al.: The STARD statement for reporting studies of diagnostic accuracy: explanation and elaboration. Ann Intern Med 2003; 138: pp. W1-W12.
46. Whiting P., Rutjes A.W., Reitsma J.B., et. al.: The development of QUADAS: a tool for the quality assessment of studies of diagnostic accuracy included in systematic reviews. BMC Med Res Methodol 2003; 3: pp. 25.
47. Maceneaney P.M., Malone D.E.: The meaning of diagnostic test results: a spreadsheet for swift data analysis. Clin Radiol 2000; 55: pp. 227-235.
48. Mayer D.: Essential evidence based medicine.2004.Cambridge University PressCambridge, UK
49. Sackett D., Strauss S., Richardson W., et. al.: Evidence-based medicine: how to practice and teach EBM.2000.Churchill-LivingstoneLondon
50. Altman D.G., Bland J.M.: Diagnostic tests. 1: Sensitivity and specificity. BMJ 1994; 308: pp. 1552.
51. Gardner M.J., Altman D.G.: Confidence intervals rather than P values: estimation rather than hypothesis testing. Br Med J (Clin Res Ed) 1986; 292: pp. 746-750.
52. Guyatt G., Jaeschke R., Heddle N., et. al.: Basic statistics for clinicians: 2. Interpreting study results: confidence intervals. CMAJ 1995; 152: pp. 169-173.
53. Halligan S., Altman D.G.: Evidence-based practice in radiology: steps 3 and 4—appraise and apply systematic reviews and meta-analyses. Radiology 2007; 243: pp. 13-27.
54. Altman D.G., Bland J.M.: Diagnostic tests 2: predictive values. BMJ 1994; 309: pp. 102.
55. Deeks J.J., Altman D.G.: Diagnostic tests 4: likelihood ratios. BMJ 2004; 329: pp. 168-169.
56. McGinn T., Jervis R., Wisnivesky J., et. al.: Tips for teachers of evidence-based medicine: clinical prediction rules (CPRs) and estimating pretest probability. J Gen Intern Med 2008; 23: pp. 1261-1268.
57. Chang P.J.: Bayesian analysis revisited: a radiologist’s survival guide. AJR Am J Roentgenol 1989; 152: pp. 721-727.
58. Barratt A., Wyer P.C., Hatala R., et. al.: Tips for learners of evidence-based medicine: 1. Relative risk reduction, absolute risk reduction and number needed to treat. CMAJ 2004; 171: pp. 353-358.
59. Jaeschke R., Guyatt G., Shannon H., et. al.: Basic statistics for clinicians: 3. Assessing the effects of treatment: measures of association. CMAJ 1995; 152: pp. 351-357.
60. Guyatt G., Jaeschke R., Heddle N., et. al.: Basic statistics for clinicians: 1. Hypothesis testing. CMAJ 1995; 152: pp. 27-32.
61. Liberati A., Altman D.G., Tetzlaff J., et. al.: The PRISMA statement for reporting systematic reviews and meta-analyses of studies that evaluate health care interventions: explanation and elaboration. PLoS Med 2009; 6: pp. e1000100.
62. Moher D., Cook D.J., Eastwood S., et. al.: Improving the quality of reports of meta-analyses of randomised controlled trials: the QUOROM statement. Quality of Reporting of Meta-analyses. Lancet 1999; 354: pp. 1896-1900.
63. Shea B.J., Hamel C., Wells G.A., et. al.: AMSTAR is a reliable and valid measurement tool to assess the methodological quality of systematic reviews. J Clin Epidemiol 2009; 62: pp. 1013-1020.
64. The AGREE Collaboration. Appraisal of Guidelines for Research & Evaluation (AGREE) Instrument. www.agreecollaboration.org . Accessed on 2/25/2011.
65. Dans A.L., Dans L.F.: Appraising a tool for guideline appraisal (the AGREE II instrument). J Clin Epidemiol 2010; 63: pp. 1281-1282.
66. Lewis S., Clarke M.: Forest plots: trying to see the wood and the trees. BMJ 2001; 322: pp. 1479-1480.
67. Deeks JJ A.D., Bradburn M.: Statistical methods for examining heterogeneity and combining results from several studies in metaanalysis.Systematic reviews in health care: meta-analysis in context.2001.BMJ BooksOxford, UK:pp. p. 285-p.312.
68. Higgins J.P., Thompson S.G., Deeks J.J., et. al.: Measuring inconsistency in meta-analyses. BMJ 2003; 327: pp. 557-560.
69. Downloadable excel spreadsheet to generate graphs of conditional probability. http://www.radiography.com/pub/ . Accessed on July 23, 2010.
70. Akobeng A.K.: Understanding diagnostic tests 2: likelihood ratios, pre- and post-test probabilities and their use in clinical practice. Acta Paediatr 2007; 96: pp. 487-491.
71. Cronin P.: Evidence-based radiology: step 3—critical appraisal of diagnostic literature. Semin Roentgenol 2009; 44: pp. 158-165.
72. Fagan T.J.: Letter: nomogram for Bayes theorem. N Engl J Med 1975; 293: pp. 257.
73. Evidence Based Imaging website. http://www.evidencebasedradiology.net/index.html . Accessed on July 23, 2010.
74. The Centre for Evidence Based Medicine at Toronto Website. http://ktclearinghouse.ca/cebm/ . Accessed on July 23, 2010.
75. Dillon J.E., Slanetz P.J.: Teaching evidence-based imaging in the radiology clerkship using the ACR appropriateness criteria. Acad Radiol 2010; 17: pp. 912-916.
76. Kelly A.M., Cronin P.: Setting up, maintaining and evaluating an evidence based radiology journal club: the University of Michigan experience. Acad Radiol 2010; 17: pp. 1073-1078.
77. Heilbrun M.E.: Should radiology residents be taught evidence-based radiology? An experiment with “the EBR Journal Club”. Acad Radiol 2009; 16: pp. 1549-1554.
78. Logie C.I., Smith S.E., Nagy P.: Evaluation of resident familiarity and utilization of the ACR musculoskeletal study appropriateness criteria in the context of medical decision support. Acad Radiol 2010; 17: pp. 251-254.

How to Write a Critically Appraised Topic (CAT)

How to write a CAT?

Step 1: Ask an Answerable Question

Step 2: Search for the Best Current Evidence

Primary study designs

Levels of evidence

The evidence pyramid

Sources of evidence for primary literature

Sources of evidence for secondary literature

Step 3: Appraise the Literature

Critically appraising primary literature

Interpreting results in diagnostic radiology

Statistical measures for therapeutic studies

Critically appraising secondary literature

Results of a meta-analysis

Summarizing the results of your literature review

Step 4: Apply

Step 5: Evaluate

Helpful tools

Good secondary sources

Good primary sources

CATmaker

Using CATs to teach evidence-based medicine/imaging

Conclusion

Acknowledgment

Supplementary Data

References

Further Reading

A Comparative Study of HRCT Image Metrics and PFT Values for Characterization of ILD and COPD

Awareness and Level of Knowledge of Interventional Radiology among Medical Students at a Canadian Institution

CAD-associated Reader Error in CT Colonography