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Critical Appraisal: An Introduction Melanie Browne HBHSc, MLIS Information Specialist.

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Presentation on theme: "Critical Appraisal: An Introduction Melanie Browne HBHSc, MLIS Information Specialist."— Presentation transcript:

1 Critical Appraisal: An Introduction Melanie Browne HBHSc, MLIS Information Specialist


3 Agenda Introduction Define Evidence-based clinical practice How to read a research article Search for best evidence Apply critical appraisal in your library Our new role Case presentation Resources

4 Evidence-Based Medicine "...the conscientious, explicit, and judicious use of current best evidence in making decisions about the care of individual patients. from Sackett, DL, et al. "Evidence based medicine: What it is and what it isn't." (BMJ 1996; 312: 71-2)

5 "Evidence based medicine (EBM) is an approach to health care that promotes the collection, interpretation, and integration of valid, important and applicable patient-reported, clinician-observed and research-derived evidence. The best available evidence, moderated by patient circumstances and preferences, is applied to improve the quality of clinical judgements" (McKibbon et al 1995).

6 Why EBM? A clinician needs to read 17 peer reviewed articles per day, every day of the year, to stay current (Haynes 1993). Haynes, R. (1993) Where's the meat in clinical journals? ACP Journal Club, 119: A23-4. There are 20 million pieces of 'evidence' of varying quality and sometime of contradictory conclusions.

7 How Can You Access, Distil and Apply Research/Evidence? Develop summaries Train clinicians and other health care decision makers to find and appraise relevant evidence Decision support systems

8 Summaries With Rigorous Methodologies Cochrane Collaboration National Centre for Clinical Excellence Centre for Clinical Effectiveness at Monash University

9 The Argument for Evidence-Based Medicine Stay up to date with the current literature Communicate effectively Make the best use of information from the history, physical examination, and diagnostic testing Avoid common pitfalls of clinical decision-making

10 Critical Appraisal The assessment of evidence by systematically reviewing its relevance, validity and results to specific situations. - Chambers, R. (1998).

11 What is best evidence? Using critical appraisal skills you can understand the methods and results of the research and then be able to assess the quality of the research.

12 Critical appraisal Exact science Critical appraisal right answer

13 Information Mastery Slawson and Shaughnessy Formula Usefulness of Medical Information = Relevance x Validity ____________________ Work to Access

14 Smith R. What clinical information do doctors need? Br Med J 1996; 313:

15 When doctors see patients they usually generate at least one question Most of the questions concern treatment Many of the questions are highly complex, simultaneously asking about individual patients and particular areas of medical knowledge

16 Often doctors are asking not simply for information but for support, guidance, affirmation, and feedback Doctors are most likely to seek answers to these questions from other doctors The best information sources provide relevant, valid material that can be accessed quickly and with minimal effort

17 Basic elements of clinical decision making Haynes RB. Loose connections between peer-reviewed clinical journals and clinical practice. Ann Intern Med 1990;113:724-8.

18 Why Should we Critically Appraise? Published research is not always reliable Published research is not always relevant To improve clinical effectiveness, we need a systematic framework to interpret research

19 Difficulties with Critical Appraisal Can be time consuming initially Doesnt provide an easy answer It could show a lack of good evidence in a particular topic

20 Key Steps to Effective Critical Appraisal 1. Are the results valid? 2. What are the results? 3. How will these results be relevant to the patient?

21 Validity and Reliability A test is valid when it measures what its supposed to. If a test is reliable, it yields consistent results. A test can be both reliable and valid, one or the other, or neither. Reliability is a prerequisite for measurement validity.

22 Reliable, but Not Valid!

23 Not Reliable, Not Valid!

24 Reliable and Valid

25 Mark Newman - Middlesex University updated 04/2001

26 What a Physician can be Faced With on a Daily Basis? ~1 - 2 questions per patient (clinics) 15/patient/day (wards) ~30% of questions are followed –People –Books –Electronic resources 40% easy to answer 30% tough to answer 30% cannot answer Source: Dawes M, Sampson U. Knowledge management in clinical practice: a systematic review of information seeking behaviour in physicians. Int J Med Inform Aug; 71(1):9-15. Review. PMID:

27 Steps to EBM 1. Formulate a clear, focused clinical question 2. PICO model 3. Search the literature for the best external evidence 4. Critically appraise the evidence for its validity and usefulness 5. Implement the useful evidence in clinical practice 6. Evaluate the results

28 Question Formulation Not easy but EXTREMELY important Good questions will –Focus/clarify your information need –Give you some idea of where to look for information –Give you searching concepts and terms

29 Background Questions …Often broad in nature …Often not patient-specific but fact based …May not need to integrate knowledge …More common early in training/new situations

30 Foreground Questions …Often for a specific patient or clinical situation …Narrow in focus …Need to integrate external information with clinical/situational data

31 PICO Structure Patients P Intervention I Comparison C Outcome O

32 Clinical Scenario What therapeutic agents can be used for rate control of atrial fibrillation (AF) in a patient with congestive heart failure (CHF)?

33 Starting Point Department: Emergency Population: Patients with atrial fibrillation and congestive heart failure Intervention: Rate control Comparison: N/A Outcome: Mortality, effectiveness of rate control

34 Patient w/ Atrial Fibrillation in congestive heart failure Comparison PICO Schematic Model Rate control Effectiveness of rate control Rhythm control / No treatment

35 Clinical problem Define the search question Choose a resource/database Create a search strategy Summarize the evidence Apply the evidence Try another relevant resource Create a search strategy Summarize the evidence Try another relevant resource General Search Strategy Adapted from: Sackett, D. et al Evidence-Based Medicine: How to Practice and Teach EBM. 2 nd Edition. Toronto: Churchill Livingstone. Poor yield

36 Study Types for Question Types DiagnosisProspective cohort study with good quality validation against Gold Standard TherapyRandomized controlled clinical trial (RCT) Etiology/ Harm RCT, cohort or case-control study (probably retrospective) PrognosisProspective cohort study

37 Does this treatment work?systematic review, RCT How good is a diagnostic test?(prospective) cohort study Should we screen?RCT What causes this disease? RCT, prospective cohort study, case control study (rare diseases) What did people think or do? cohort study, cross-sectional survey, qualitative study


39 How can we do Critical Appraisal? Use common sense Use simple checklists Use different checklists depending on the different types of studies (i.e., RCTS, systematic reviews etc) Checklists help you focus on the important parts of the article

40 Research Methodology Who were the participants of the study? How were they recruited? Was there bias in the recruiting methods? How was the data collected? What statistical tests were used? Where the data collection methods accurate?

41 Critical appraisal questions What is the paper about? Why was the study done? What type of study was done? Was it primary research (experiment, RCT, cohort, case-control, cross- sectional, longitudinal, case report/series)?

42 Critical appraisal questions Was it secondary research (overview, systematic review, meta-analysis, decision analysis, guidelines development, economic analysis)? Was the design appropriate (for study on treatment, diagnosis, screening, prognosis, or causation)?

43 Critical appraisal questions Was the study ethical? Is the design right? (BMJ Editor's checklists)

44 How to Read a Research Article? – First Glance. Purpose of reading the paper. Do not read the abstract. Read the title, find out who the authors are and where they work, look for sources of funding and conflicts of interest Look at the tables and figures Is there a diagram to show the flow of participants through each stage of the study Why was the study done and what hypothesis were the authors testing? What is broadly the topic of research? Therapy, Diagnosis, Screening, Prognosis, Causation? What type of study was done? Is this a primary (experimental, clinical trial, survey) or a secondary paper (review, meta-analysis, guideline, economic analysis)? Was the study design appropriate? Now proceed to a critical appraisal of the paper

45 Case Presentation Read the Ray et al(2008) paper and divide the group into 2 – for a debate on the paper Breast size and risk of type 2 diabetes mellitus. CMAJ

46 Ray and colleagues studied data from women in conjunction with the Nurses' Health Study II and found that breast size at age 20, assessed by recall of bra cup size, correlated positively with the incidence of type 2 diabetes

47 After adjustment for relevant factors, such as body mass index, waist circumference and family history of diabetes, the hazard ratio dropped to 1.58 but remained significant.

48 Nurses' Health Study II population data emanates from women who were mainly of white ancestry, and that their analysis is based on recall and self-report.

49 New Role of Health Sciences Librarians Teaching access to the literature and other information resources Teaching use of technology as a means to access and manage information Teaching skills in information organization and critical appraisal

50 Role of Librarians as Information Clinicians Information Clinician Medical Informatics Tutor EBM Educator

51 Informationist A discipline requiring a combination of the skills of a librarian, a clinical epidemiologist and a medical scientist Davidoff, F. & Florance,V. (2000) The Informationist: A New Health Profession? Annals of Internal Medicine, 132:

52 Effective INFORMAtician Knows categories of information resources …therapy, diagnosis, prognosis …synthesized resources vs original studies Knows strengths/weaknesses of information resources Knows when to use each category Knows that some resources are better than others in certain situations …Cochrane diagnostic accuracy data? Knows what to do with the results

53 Practical solutions - Librarian as a partner on the teaching team; teachable moments Formal hospital library educational programs have focused on orientation and instruction in the use of bibliographic tools. i.e.- LATCH (Literature Attached to Charts) and clinical medical librarianship

54 Critical Appraisal Skills Training Research methodology Statistical techniques

55 Courses for Librarians Out There CILIP: the Chartered Institute of Library and Information Professionals Critical appraisal skills for healthcare librarians: building on the basics g/2008/libinfo/criticalappraisalskillsforhe althcarelibrariansbuildingonthebasics.htm

56 General Resources: CASP (Critical Appraisal Skills Programme) - part of the Public Health Resource Unit based at Oxford, CASP runs training workshops on critical appraisal skills. CASP (Critical Appraisal Skills Programme) Evidence-Based Medicine Toolkit - hosted by the University of Alberta, this is an online "box" of handy tools to help you find, appraise, and apply in practice, evidence-based researchEvidence-Based Medicine Toolkit How to read a paper - a set of ten guides from the BMJ (individual links given in the relevant section below).How to read a paper Levels of Evidence - a ranking system used to rank various study designs in order of evidence-based merit: systematic reviews/meta-analyses and well conducted randomised controlled trials (RCTs) are usually seen as the best form of "evidence", with research based on the outcome of a case series placed somewhere near the bottomLevels of Evidence Netting the Evidence - search for the keyword "appraisal" to find a quality assessed list of appraisal resourcesNetting the Evidence User's guides to evidence based practice - based on a series of articles published in JAMA, these guides give comprehensive advice on how to find, appraise and apply research in practiceUser's guides to evidence based practice

57 Keeping Current Daily InfoPOEMs bmjupdates+ Tables of contents of journals (e.g. JAMA) –From journal itself –My NCBI from PUBMED

58 Absolute Risk Difference Absolute Risk Reduction Absolute Benefit Increase Confidence Intervals Intention to treat Likelihood Ratio Numbers Needed to Treat (NNT) Odds Ratio P Value Predictive Value of tests Relative Risk Relative Risk Reduction Sensitivity Specificity


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