1 GATE Graphic Appraisal Tool for Epidemiology 1991

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GATE: Graphic Appraisal Tool for Epidemiology 1991 - 2015 1 picture, 2 formulas & 3 acronyms 2

GATE: Graphic Appraisal Tool for Epidemiology Graphic Architectural Tool for Epidemiology Graphic Approach To Epidemiology making epidemiology accessible 3

4 th year medical students 1991

Jerry Morris numerator epidemiology = denominator In: Uses of Epidemiology 1957 5

presentation outline GATE is a framework for: 1. study design 2. study analysis 3. study error 4. practicing EBM 1 picture, 2 formulas & 3 acronyms 7

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GATE: a framework for study design 1 picture every epidemiological study can be hung on the GATE frame 1 picture, 2 formulas & 3 acronyms 9

1 picture: GATE frame cohort of British doctors smoking status allocated by measurement (observation) smokers lung cancer yes events counted no non-smokers followed for 10 years cohort / longitudinal / follow-up study 1 picture, 2 formulas & 3 acronyms 10

1 st acronym: PECOT British doctors P Participants randomly allocated to aspirin or placebo Exposure E C Comparison aspirin placebo Outcomes yes MI no O T Time 5 years randomised controlled trial 1 picture, 2 formulas & 3 acronyms 11

middle-aged Americans P body mass index measured overweight diabetes status measured in all participants yes no E C ‘normal’ weight O T cross-sectional (prevalence) study 12

middle-aged American women P receive mammogram screening test mammogram positive breast cancer yes no E C O mammogram negative T diagnostic test (prediction) study 13

middle-aged American women P Gold Standard breast cancer positive mammogram negative test E C O no breast cancer T diagnostic (test accuracy) study 14

P smokers lung cancer E C non-smokers smoking status measured cases yes no O controls T case-control study (all nested in virtual cohort studies) 15

£ 100

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GATE: a framework for study analysis: 1 st formula: occurrence = outcomes ÷ population the numbers in epidemiological studies can be hung on the GATE frame 1 picture, 2 formulas & 3 acronyms 18

1 st formula: occurrence of outcomes = number of outcomes ÷ number in population/group British doctors P Participant Population smoking status measured Exposure Group EG CG Comparison Group smokers Outcomes Lung cancer non-smokers yes no a O b T Time 10 years 19

Population P British doctors smoking status measured Exposure Group EG CG Comparison Group smokers Outcomes Lung cancer non-smokers yes no a O b T Time 10 years Exposure Group Occurrence (EGO) = a÷EG = number of outcomes (a) ÷ number in exposed population (EG) 20

P British doctors Population randomly allocated Exposure Group EG CG Comparison Group aspirin Outcomes MI placebo yes no a O b T Time 5 years Comparison Group Occurrence (CGO) = b÷CG = number of outcomes (b) ÷ number in comparison population (CG) 21

Epidemiology = Numerator ÷ Denominator P middle-aged American women Participant Population receive mammogram screening test D Exposure Group EG mammogram positive Outcomes yes breast cancer no a Comparison Group mammogram negative N O T Time 22

the goal of all epidemiological studies is to calculate EGO and CGO P British doctors smoking status measured smokers yes EGO: Occurrence (risk) of no cancer in smokers EG a CG non-smokers O b Lung cancer 10 years T CGO: Occurrence of cancer in nonsmokers 23

Middle-aged Americans P Body Mass Index (BMI) measured High BMI high low EGO: Average blood glucose in EG EG CG O Low BMI CGO: Average blood glucose in CG 24

Middle-aged Americans P Body Mass Index (BMI) measured High BMI blood glucose high low E C Low BMI O T cross-sectional study with numerical measures 25

Middle-aged American women P Gold Standard Breast cancer mammogram positive negative EGO: likelihood of a positive mammogram if breast cancer E C O no Breast cancer T CGO: likelihood of a positive mammogram if no breast cancer 26

1 st formula: occurrence = outcomes ÷ population its all about EGO and CGO • EGO ÷ CGO = Relative Risk (RR) • EGO – CGO = Risk Difference (RD) measures of occurrence: risk; rate; likelihood; probability; average; incidence; prevalence 27

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GATE: framework for nonrandom error 2 nd acronym: RAMBOMAN Recruitment Allocation Maintenance Blind Objective Measurements ANalyses 1 picture, 2 formulas & 3 acronyms 29

Study setting Eligible population RAMBOMAN recruitment process P P Recruitment of participants ‘who are the findings applicable to? ’ 30

RAMBOMAN: ‘were participants well Allocated to exposure & comparison groups? ’ was Allocation to EG & CG successful? RCT: allocated by randomisation (e. g to drugs) Cohort: allocated by measurement (e. g. smoking) EG & CG EG CG similar at baseline? T O EG CG T E & C measures accurate? O 31

P RAMBOMAN ‘were Participants well Maintained in the groups they were allocated to? ’ EG CG T O completeness of follow-up compliance contamination co-interventions 32

P EG CG RAMBOMAN ‘were outcomes well Measured? ’ were they measured Blind to whether participant was in EG or CG ? O T 33

P RAMBOMAN ‘were outcomes well Measured? ’ EG CG were they measured Objectively? O T 34

RAMBOMAN P ‘were the ANalyses done well? ’ EGA CGA EGC CGC a T O If RCT were Intention To Treat (ITT) analyses done? b 35

P RAMBOMAN ‘were the ANalyses done well? ’ EG CG adjustment for baseline differences / confounding? O T 36

GATE: random error: 2 nd formula: random error = 95% confidence interval sample from a population EGO ± 95% CI CGO ± 95% CI There is about a 95% chance that the true value in the underlying population lies within the 95% CI (assuming no non-random error) 1 picture, 2 formulas & 3 acronyms 37

GATE: a framework for error in systematic reviews & meta-analyses: 3 rd acronym: FAITH 1 picture, 2 formulas & 3 acronyms 38

systematic review: a study of studies study sources studies screened studies appraised & allocated: included excluded studies summarised & pooled if homogeneous 39

critical appraisal of SR: FAITH study sources Find studies screened Appraise studies appraised & allocated: Include included Total Heterogeneity? excluded studies summarised & pooled if homogeneous 40 1 picture, 2 formulas & 3 acronyms

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GATE: framework for the 4 steps of EBP 42

the steps of EBP: 1. Ask 2. Acquire 3. Appraise 4. Apply & Act 43

EBP Step 1: ASK - turn your question into a focused 5 -part PECOT question P 2. Exposure 4. Outcomes E yes no 1. Participants C O 3. Comparison T 5. Time 44

EBP Step 2: ACQUIRE the evidence – use PECOT to help choose search terms P Exposure Outcomes E yes no Participants C O Comparison T Time 45

EBP Step 3: APPRAISE the evidence – with the picture, acronyms & formulas Recruitment P P Allocation E E C O T Maintenance blind objective Measurements ANalyses Occurrence = outcomes ÷ population Random error = 95% Confidence Interval 46

APPLY the evidence by AMALGAMATING the relevant information & making an evidencebased decision: ’ the X-factor © 47

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X-factor: making evidence-based decisions epidemiological evidence person values & preferences family community economic system features patient’s clinical circumstances practitioner political ph lth ea l ca gi lo l lh ho ica yc ys ps cia so X legal Practitioner e pertise: ‘putting it all together’ - the art of practice Clinical expertise in the era of evidence-based medicine and patient choice. EBM 2002; 736 -8 (March/April) 49

GATE critically appraised topic (CATs) forms find these at: www. epiq. co. nz

GATE CAT – 4 -sheet workbook (in Excel) sheet 1: GATE-Ask & Acquire 51

GATE CAT – 3 -sheet workbook (in Excel) sheet 2: GATE-Appraise (with calculator) 52

GATE CAT – 3 -sheet workbook (in Excel) sheet 3: GATE-Apply 53

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