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Research Design & EBM

Research Design & EBM. Ravi Kant MS, DNB, FAMS, FRCS (Edin), FRCS (Glasg), FRCS (Engl.), FRCS (Irel.), FACS, FICS, FAIS Professor of Surgery. Science. Intelligent Hypothesis Experiments & analysis of results prove that hypothesis is correct. Replicable universally= Most Important.

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Research Design & EBM

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  1. Research Design &EBM Ravi Kant MS, DNB, FAMS, FRCS (Edin), FRCS (Glasg), FRCS (Engl.), FRCS (Irel.), FACS, FICS, FAIS Professor of Surgery

  2. Science • Intelligent Hypothesis • Experiments & analysis of results prove that hypothesis is correct. • Replicable universally= Most Important

  3. Evidence based medicine: what it is and what it isn't • Integrating individual clinical expertise and the best external evidence • BMJ 1996;312:71-72 (13 January)  • Editorial

  4. Evidence-based health care? • = best evidence

  5. Evidence-based health care? • decision-making

  6. Observational study • Evaluating results of condition or treatment in a defined population

  7. Retrospective: analyzing past events

  8. Prospective: • collecting data contemporaneously

  9. Case-control • Series of patients with a particular disease or condition contrasted with matched control patients

  10. Cross-sectional Measurements mode on a single occasion, not looking at whole population but selecting small similar group & expanding results

  11. Longitudinal • Measurements are taken over a period of time, not looking at whole population but selecting small similar group & expanding results

  12. Experimental • Two or more treatments are compared. Allocation to treatment groups is under the control of the researcher

  13. Randomized • Two randomly allocated treatments

  14. Prospective Randomized controlled Includes control group with no treatment = GOLD STANDARD

  15. Confidence Interval • To p or not to p

  16. RR • Relative Risk

  17. Hazard ratio/ Odds ratio

  18. Systemic Review • reliable • systematic • predefined, explicit methodology • minimize bias • Systemic review+ Statistics= meta-analysis

  19. Systemic Review • = ?

  20. Levels of evidence • 1= Meta-analyses of Prospective Double blind randomized controlled trials • 2=Prospective Randomized Controlled study/ Meta-analyses of retrospective studies • 3= Case series/ Cohort study • 4= Case report/ observational • 5= Expert opinion

  21. Evidence grade: I • I (High): the described effect is plausible, precisely quantified and not vulnerable to bias

  22. Evidence grade: I • II (Intermediate): the described effect is plausible but is not quantified precisely or may be vulnerable to bias

  23. Evidence grade : III • III (Low): concerns about plausibility or vulnerability to bias severely limit the value of the effect being described and quantified

  24. Strength of recommendation Definition A • A=Recommendation based on consistent and good quality patient-oriented evidence

  25. Strength of recommendation Definition B • B=Recommendation based on inconsistent or limited quality patient-oriented evidence

  26. Strength of recommendation Definition C • C=Recommendation based on consensus, usual practice, opinion, disease-oriented evidence or case series for studies of diagnosis, treatment, prevention, or screening.

  27. Recommendation grade: A • A (Recommendation): there is robust evidence to recommend a pattern of care

  28. Recommendation grade : B • B (Provisional recommendation): on balance of evidence, a pattern of care is recommended with caution

  29. Recommendation grade : C • C (Consensus opinion): evidence being inadequate, a pattern of care is recommended by consensus

  30. US Government Agency for Health Care Policy and Research (AHCPR):A • A: requires at least one randomized controlled trial as part of the body of evidence.

  31. US Government Agency for Health Care Policy and Research (AHCPR):B • B: requires availability of well-conducted clinical studies but no randomized controlled trials in the body of evidence.

  32. US Government Agency for Health Care Policy and Research (AHCPR):C • C: requires evidence from expert committee reports or opinions and/ or clinical experience of respected authorities. Indicates absence of directly applicable studies of good quality

  33. Grading of evidence • Ia: Systematic review or meta-analysis of randomized controlled trials • Ib: at least one randomized controlled trial • IIa: at least one well-designed controlled study without randomization • IIb: at least one well-designed quasi-experimental study, such as a cohort study • III: well-designed non-experimental descriptive studies, such as comparative studies, correlation studies, case–control studies and case series • IV: expert committee reports, opinions and/or clinical experience of respected authorities

  34. Grading of recommendations • A: based on hierarchy I evidence • B: based on hierarchy II evidence or extrapolated from hierarchy I evidence • C: based on hierarchy III evidence or extrapolated from hierarchy I or II evidence • D: directly based on hierarchy IV evidence or extrapolated from hierarchy I, II or III evidence

  35. Research can be Quantitative: A medical condition is analyzed systematically using hard, objective end point such as death or amputation.

  36. Research can be Qualitative Data come from patient narratives, and the psychosocial impact of the disease and its treatment are analyzed, for example narratives of breast cancer.

  37. Project design include: Sample size. Eliminating bias. Study protocol. Ethics.

  38. Sample size An incorrect sample size is probably the most frequent reason for research to be invalid. Never forget that more patients will need to be randomized than the final sample size to take into account patients who die, drop out or are lost to follow up.

  39. Sample size • nX[r(100-r)+s(100-s)]/(r-s)2

  40. Type I error • Benefit is perceived when really there is none (false positive)

  41. Type II error • Benefit is missed because the study has small numbers (false negative)

  42. Eliminating bias: Single blind The observers or recorders who do not know which treatment has been used.

  43. Eliminating bias: Double blind Neither patient nor researcher is aware of which therapy has been used until after study has finished, & these are the best randomized studies.

  44. The Cochrane Collaboration • Best evidence • an international not-for-profit and independent organization, • It produces and disseminates systematic reviews of healthcare interventions and promotes the search for evidence in the form of clinical trials and other studies of interventions. • The Cochrane Collaboration was founded in 1993 and named after the British epidemiologist, Archie Cochrane.

  45. Current reliable evidence-based medicine resources for the busy clinician -1 • American College of Physicians Journal Club http://www.acpj.org • American Family Physician http://www.aafp.org/afp • Bandolier http://www.rj2.ox.ac.uk/bandolie • Clinical Evidence http://www.clinicalevidence.com

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