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Introduction to Critical Appraisal

Introduction to Critical Appraisal. Yulia Lin, MD, FRCPC Transfusion Medicine & Hematology Sunnybrook Health Sciences Centre University of Toronto TMR Journal Club, September 6, 2011. Why is Critical Appraisal important?. Vast amount of literature. New Studies in Transfusion.

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Introduction to Critical Appraisal

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  1. Introduction to Critical Appraisal Yulia Lin, MD, FRCPC Transfusion Medicine & Hematology Sunnybrook Health Sciences Centre University of Toronto TMR Journal Club, September 6, 2011

  2. Why is Critical Appraisal important?

  3. Vast amount of literature

  4. New Studies in Transfusion

  5. New Studies in Transfusion Past Studies in Transfusion

  6. New Studies in Transfusion Studies in other Sub-specialties Past Studies in Transfusion

  7. Why critical appraisal is important? • Impossible to keep up with all of the literature • Enables us to distinguish stronger evidence from weaker evidence • Allows us to appropriately incorporate the evidence into our practice so as to improve patient care

  8. Transfusion Medicine Residency Objectives • Scholar • 2 - Evaluate medical information and its sources critically, and apply this appropriately to practice decisions • Describe the principles of critical appraisal • Critically appraise retrieved evidence in order to address a clinical question • Integrate critical appraisal conclusions into clinical care • Critically review published literature and apply appropriate utilization principles/practices /guidelines

  9. Purpose of TMR Journal Club • To present a recent article in the transfusion literature • To learn how to critically appraise the medical literature

  10. Steps to a successful JC • Choosing the article • Presenting the article • Critically appraising the article

  11. Choosing an article… • Where to find an article? • Recent table of contents • NEJM, Lancet, JAMA • Transfusion, Vox Sanguinis, Blood, etc. • Transfusion Medicine Reviews – Journal Club • Transfusion Medicine Community • List of interesting articles

  12. Choosing the article… • Which article? • Relevant • Interesting to you • What type of article? • Any article • But some are easier than others…

  13. Type of articles • Randomized controlled trials – Therapy • Observational studies – Harm • Systematic Reviews • Guidelines • Diagnosis • Prognosis

  14. First, a review…

  15. Randomized Controlled Trial Intervention A Population Outcomes measured Randomization Intervention B

  16. Randomized Controlled Trial 16 Intervention A Population Outcomes measured Randomization Intervention B • Which article?

  17. Randomized Controlled Trial Randomization • Fill in the blanks above: • Population? Intervention? Outcome?

  18. Randomized Controlled Trial 18 Intervention A Population Outcomes measured Randomization Intervention B • Which article?

  19. Randomized Controlled Trial 19 Randomization • Fill in the blanks above: • Population? Intervention? Outcome?

  20. Observational Case-Control Population Exposure to Risk Factor Exposed Cases (+Disease) Yes No Control (No disease) Yes No

  21. Observational Case-Control Population Exposure to Risk Factor Exposed Cases (+Disease) Yes No Control (No disease) Yes No Retrospective

  22. Observational Case-Control Population Exposure to Risk Factor Exposed Cases (+Disease) Yes No Control (No disease) Yes No Which article?

  23. Observational Case-Control Exposed Cases? Yes No Risk factor? Controls? Yes No Fill in the blanks: Population? Who are the cases and controls? What are the risk factors?

  24. Observational Cohort Cohort without Disease Population Exposure to Risk Factor Disease Yes No Exposed Cohort Yes No Not exposed

  25. Cohort Studies Past Present Future Cohort assembled Follow-up Retrospective Cohort Study

  26. Cohort Studies Past Present Future Cohort assembled Follow-up Retrospective Cohort Study Which article?

  27. Cohort Studies Past Present Future Fill in the blanks: Who is the cohort? What is the risk factor? What is the outcome?

  28. Cohort Studies Past Present Future Cohort assembled Follow-up Retrospective Cohort Study Cohort assembled Follow-up Prospective Cohort Study

  29. Cohort Studies Past Present Future Cohort assembled Follow-up Retrospective Cohort Study Cohort assembled Follow-up Prospective Cohort Study Which article?

  30. Cohort Studies Past Present Future Cohort assembled Follow-up Retrospective Cohort Study Fill in the blanks above: Who is the cohort? What is the risk factor? What is the outcome?

  31. Systematic Review • Overview • Summary of the medical literature that attempts to address a focused clinical question • Systematic review • Using methods designed to reduce the likelihood of bias • Meta-analysis • Review that uses quantitative methods to summarize the results

  32. Systematic Review • Systematic review • Using methods designed to reduce the likelihood of bias • Meta-analysis • Review that uses quantitative methods to summarize the results Meta-analysis of the randomized controlled trials of the hemostatic efficacy and capacity of pathogen-reduced platelets. Vamvakas EC. Transfusion May 2011;51:1058-71

  33. Guidelines • “Systematically developed statements to assist practitioner and patient decisions about appropriate health care for specific clinical circumstances” • Attempt to address all issues and values relevant to a clinical decision • Attempt to distill a large body of medical expertise into a convenient, readily usable format • Make explicit recommendations with definite intent to influence what clinicians do Field MJ. Clinical practice guidelines. 1990 Hayward et al. JAMA 1995;274:570-4 Cook et al. Ann Int Med 1997;127:210-6

  34. Guidelines • “Systematically developed statements to assist practitioner and patient decisions about appropriate health care for specific clinical circumstances” Guidelines on oral anticoagulation with warfarin, 4th edition. BCSH 2010. http://www.bcshguidelines.com/documents/warfarin_4th_ed.pdf

  35. How to do a critical appraisal?

  36. Critical appraisal methods • Most are based on Users’ Guides to the Medical Literature • Available in a textbook form (2nd ed) • Brief version http://www.ebem.org/usersguide.html • For guidelines, different instruments • AGREE instrument: http://www.agreetrust.org/resource-centre/agree-ii/

  37. Steps to Critical Appraisal • Are the results valid? • Have the results been influenced in a systematic fashion so as to lead to a false conclusion? • What are the results? • How can I apply the results to patient care?

  38. RCT Intervention A Population Outcomes measured Randomization Intervention B

  39. RCT - Are the results valid? Intervention A Population Outcomes measured Randomization Intervention B Was the assignment of patients to treatment randomized?Were all patients who entered the trial accounted for and attributed at its conclusion?Were patients, clinicians and study personnel kept "blind" to treatment received?Were the groups similar at the start of the trial?Aside from the experimental intervention were the groups treated equally?

  40. RCT - Are the results valid? 43 Restrictive Hb <70 CPB Hb <75 postop Elective cardiac Surgery N=50 Adherence to transfusion strategies Randomization Liberal Hb <95 CPB Hb <100 postop Was the assignment of patients to treatment randomized?Were all patients who entered the trial accounted for and attributed at its conclusion?Were patients, clinicians and study personnel kept "blind" to treatment received?Were the groups similar at the start of the trial?Aside from the experimental intervention were the groups treated equally?

  41. RCT - What were the results? Intervention A Population Outcomes measured Randomization Intervention B How large was the treatment effect? How precise was the estimate of the treatment effect?

  42. RCT - What were the results? 45 Intervention A Population Outcomes measured Randomization Intervention B How large was the treatment effect? How precise was the estimate of the treatment effect?

  43. RCT - How can I apply the results to patient care? Intervention A Population Outcomes measured Randomization Intervention B Can the results be applied to my patients?

  44. RCT - How can I apply the results to patient care? Intervention A Population Outcomes measured Randomization Intervention B Can the results be applied to my patients?Were all clinically important outcomes considered? Are the likely treatment benefits worth the potential harm and costs?

  45. Observational Cohort Cohort without Disease Population Exposure to Risk Factor Disease Yes No Exposed Cohort Yes No Not exposed

  46. Cohort Studies 49 Past Present Future Pts receiving high plasma volume donations from LAPS II Incidence of TRALI Exposure to HLA ab pos vs neg donations LAPS II: a retrospective cohort study of transfusion-related acute lung injury in recipients of high-plasma-volume human Leukocyte antigen antibody-positive or –negative components. Kleinman et al. Transfusion. Published online Mar 29, 2011.

  47. Cohort - Are the results valid? 50 Cohort without Disease Exposure to Risk Factor Disease TRALI No Pts receiving high plasma volume donations from LAPS II HLA ab pos All hospital patients TRALI No HLA ab neg Except for the exposure under study, were the compared groups similar to each other?Were the outcomes and exposures measured in the same ways in both groups?Was the follow-up of patients sufficiently long and complete?Is the temporal relationship correct?Is there a dose-response gradient?

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