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Rod Jackson EPIQ group University of Auckland, NZ www.epiq.co.nz

GATE: ‘EBP with pictures’. a G raphic A pproach to T eaching E BP a G raphic A ppraisal T ool for E BP G raphic A rchitectural T ool for E pidemiology. Rod Jackson EPIQ group University of Auckland, NZ www.epiq.co.nz. 5/9/05 Oxford. ©.

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Rod Jackson EPIQ group University of Auckland, NZ www.epiq.co.nz

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  1. GATE: ‘EBP with pictures’ a Graphic Approach to Teaching EBP a Graphic Appraisal Tool for EBP Graphic Architectural Tool for Epidemiology Rod Jackson EPIQ group University of Auckland, NZ www.epiq.co.nz 5/9/05 Oxford ©

  2. What is evidence-based practice (EBP)? Policy Evidence ‘ways of knowing” Practitioner Patient

  3. What is evidence-based practice? Policy Evidence ‘ways of knowing” Practitioner Patient

  4. What is evidence-based practice? ‘using more evidence from clinical epidemiology (on diagnosis, prognosis & interventions) to inform decisions’ • more comprehensively (systematic reviews) • more critically (evidence appraisals) • more quantitatively (probabilities)

  5. What is the ‘evidence’ of EBP? ‘clinically relevant evidence, sometimes from basic science, but especially from patient-centred clinical research into the accuracy of diagnostic tests*, the power of prognostic markers*, and the efficacy & safety of interventions*’ Modified from Sackett et al. EBM 2nd Edition 2000 * from clinical epidemiological studies

  6. Epidemiological evidence is the cornerstone of EBP ‘understanding epidemiological study design is the essential skill for teachers of EBP’

  7. The 4 (5) steps of EBP Ask a focussed clinical question Search for appropriate epidemiological evidence to help answer question Appraise (critically) the evidence (validity, impact, precision) Synthesise the evidence with patient, clinical & policy issues; then apply (i.e. answer question) Assess/ evaluate practice (clinical audit). Modified from DS et al

  8. CATs: Critically Appraised Topics: ‘a tool for modeling the steps of EBP’ www.epiq.co.nz

  9. CAT forms: (in Excel) Intervention Diagnosis Prognosis/Risk (coming) Systematic Reviews (coming) download from: www.epiq.co.nz

  10. The GATE Approach: every epidemiological study hangs on the GATE frame • there is only one study design: • RCT - interventions • Cohort studies - prognosis / interv./ aetiology • Cross-sectional studies - diagnosis • Case-control studies - interv./aetiol. GATE: Graphic Appraisal Tool for Epidemiology

  11. GATE Frame: PECOT P • Population • Exposure • Comparison • Outcome • Time E C T O © GATE: Graphic Appraisal Tool for Epidemiology

  12. GATE: epi study design (P) Population P ©

  13. Source Population: 68,561 women screened from 20 outpatients/community screening centres Eligible Population: Post-menopausal, established CHD, < 80 yrs, no MI in last 6 mths, no HRT last 3 months P Participant Population: all eligibles invited (2763)

  14. GATE: epi study design (E&C) Population P Comparison (C) [control] Exposure (E) [or intervention] E C ©

  15. HRT Identical Placebo Comparison (C) [control] Exposure (E) [or intervention] E C

  16. GATE: epi study design (O) Population P Comparison Exposure E C a b yes Outcomes (O) O no c d ©

  17. 1º CHD E C yes Outcomes (O) O no

  18. mean HDL cholesterol (mmol/L) HRT Placebo Outcomes (O) 1.4 1.27

  19. GATE: epi study design (T) Population P Comparison E C Exposure T Time (T) Outcomes O ©

  20. E C T Time (T) O CHD measured over 4.1 years(longitudinal)

  21. E C T Time (T) O HDL cholesterol measured at 1 year(cross-sectional)

  22. GATE: epi study design Population P Comparison E1 C Multiple Exposure categories E2 E3 Multiple Outcome categories ©

  23. GATE: epi study design Population P E Continuous measure of Exposure: e.g. body mass index high…med..low Correlation coefficient low Continuous measure of Outcomes e.g. lipids O medium high ©

  24. Cohort (Follow-up) study: archetypal epidemiological study Population P cohort non-randomised allocation EG CG Exposure Group Comparison Group Real life time T Time ill-health Outcomes O © “Life” is a cohort study: a “natural experiment”

  25. Cohort study (prognosis): Danish Breast Cancer Cooperative Cohort of women diagnosed with breast cancer Population P Non-randomised allocation to prognostic groups No childbirth <2 yrs before diagnosis childbirth <2yrs before diagnosis EG CG T 10 years yesdeath .no O © Kroman et al. BMJ 1997;315:851-5

  26. Cohort study (aetiology): British Doctors Study Cohort of British Doctors established in 1951 Population P Non-randomised allocation (self-reported smoking) EG CG Non-smokers Smokers 50 years T yesLung Cancer .no O © Doll et al. BMJ 2004;328:1519

  27. Cohort study (intervention): Nurses Health Study Cohort of US Nurses Population P Non-randomised allocation (self-reported use) EG CG No HRT HRT 10 years T yesCHD .no O © Stampfer et al. NEJM 1991;325:756-62

  28. Randomised Controlled Trial (RCT): HERS Population P Randomised allocation Exposure (intervention): HRT Comparison (control): Placebo EG CG T Time Outcomes: CHD O © Hulley et al. JAMA1998;280:605-13

  29. Case series Population P Exposure Grp EG C No one allocated to Comparison Group T Time Outcomes O ©

  30. Before-After Study (& cross-over study) Population P CG Comparison Grp Allocation: randomised or non-randomised EG Exposure Grp T Time Outcomes O ©

  31.  LTPA  angina  LTPA  angina Cross-sectional (prevalence) study/survey: PECO Population P Real life time O EG CG Time ? O EG CG © E/C assignment & Outcomes assessed in cohort at same Time

  32. Diagnostic Test Accuracy Study (cross-sectional) Population P Allocation by measurement EG:Gold Standard +ve CG:Gold Standard -ve EG CG Time GS+ GS- +Test Outcomes .- b a O d c ©

  33. Diagnostic Test Study Application (cross-sectional) Population P Allocation by measurement EG:Test +ve CG:Test -ve EG CG Time T+ T- +ve predictive value. b a O -ve predictive value. d c ©

  34. GATE: the NUMBERS Population P= Exposure Group EG= CG= Comparison Group Time T= a= b= Outcomes c= d= ©

  35. GATE: the numbers = HERS P= 2763 Population EG= 1380 CG= 1383 Exposure Group Comparison Group Time a= 172 b= 176 T= 4.1 yrs Outcomes ©

  36. Occurrence = outcome / population P= Population Denominators = EG x T and CG x T sub-populations EG= CG= T b= + a= Numerators = a or c and b or d outcomes - c= d= © Epidemiology = numerator / denominator (E=N/D)

  37. GATE: occurrence = numerator / denominator P= T= EG= CG= Exp. Group Occurrence EGO = a / EG x T Comp. Group Occurrence CGO = b / CG x T a= b= c= d= EGO = c / EG x T EGO = d / EG x T ©

  38. GATE: occurrence HERS P= 2763 T= 4.1 yrs EG= 1380 CG= 1383 Exp. Group Occurrence EGO = A / EGxT= 172/1380 x 4.1= 30.40/1000/yr A= 172 B= 176 Comp. Group Occurrence CGO = B / CGxT= 176/1383 x 4.1= 31.04/1000/yr

  39. Occurrence EGO = Exposure Group Occurrence (A/[EGxT]) CGO = Comparison Group Occurrence (B/[CGxT] = 30.40 / 1000 persons / year = 30.40 / 1000 persons / year

  40. Effects: comparing occurrences Relative Effect/Risk (RR) = EGO CGO e.g. relative risk, risk ratio, prevalence ratio, incidence ratio Absolute Effect/Risk Difference (RD) = EGO - CGO e.g. risk difference, absolute risk Number Needed to Treat (NNT) to prevent/cause 1 event = 1/RD

  41. Using GATE to frame all the steps of EBP www.epiq.co.nz

  42. STEP 1: Ask focussed 5-part questions: 1. Participants (patient/population group) 2. Exposure (intervention if about therapy) 3. Comparison (there is always an alternative!) 4. Outcome 5. Timeframe

  43. STEP 2: Search for best evidence using 3/4-part search terms: 1. Participants (patient/population group) 2. Exposure (intervention if about therapy) 3. Comparison (e.g placebo) 4. Outcome

  44. Step 3a: appraise the evidence - hang the study & numbers on the GATE frame: PECOT Population P Exposure Comparison E C T Outcome O Time ©

  45. Step 3b:appraise the evidence: ‘did the right people get in the right places? RAMM Representative of who? P Allocated appropriately? Measured well?-blinded or objective-complete E C T Measured well?-blinded or objective-complete O ©

  46. R A M M

  47. EBCP Step 4: applying the evidence - the X-factor ©

  48. X-factor: making evidence-based decisions Epidemiologic evidence Patient preferences Policy issues clinical considerations ‘clinical expertise: other ways of knowing’ X-factor: integrating everything

  49. Step 4

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