Making evidence more accessible using pictures Rod Jackson Oxford 8/9/09

What is Evidence Based Practice?

What is Evidence Based Practice?

The 6 steps of Evidence Based Practice ASK a focussed question ACCESS - search for epidemiological evidence to help answer question APPRAISE the evidence for its validity, effect size, precision) AGGREGATE the evidence with patient/community, clinical/hlth & policy issues & make an evidence-based decision APPLY your decision [AUDIT your practice (i.e. check your actual practice against evidence-based practice on a regular basis)].

Graphic Approach To Epidemiology The GATE frame © Graphic Approach To Epidemiology

PECOT: the 5 parts of every epidemiological study Participants Exposure Group Comparison Group E C Outcomes O Time T All epidemiological studies can be hung on the GATE frame

EBP Step 1: ASK - turn your question into 5 parts (PECOT) Participants (patient(s) you want to treat) Exposure (an intervention if about therapy) Comparison (there is always an alternative! - another therapy, nothing … Outcome (usually a disease or condition you want to prevent or manage) Time frame (over which you expect a result)

Use the PECOT components to choose search terms EBP Step 2: ACCESS - search for the best evidence to answer your questions Use the PECOT components to choose search terms

EBP Step 3: Appraise the evidence using PECOT & RAMBO on the GATE frame Recruitment Allocation Maintenance Blind or Objective measurements & processes E C O T

EBP Step 4: AGGREGATE the relevant information & make an evidence-based decision:’ the X-factor ©

X-factor: making evidence-based decisions Epidemiologic evidence Clinical / population health considerations Patient / community preferences Policy issues expertise: ‘putting it all together’ the art of practice

Step 5 APPLY Implementation!

Step 6: AUDIT - evaluate & improve performance 1. Determine ‘best’ practice (EBP Steps 1-4) 2. Assess current practice: survey 3. Compare with best practice - is there a gap? 4. Consider reasons for gap, identify processes to reduce gap & implement 5. Re-survey: is there any improvement? = quality improvement / audit

GATE Graphic Approach To Epidemiology Graphic Appraisal Tool for Epidemiology Graphic Architectural Tool for Epidemiology www.epiq.co.nz

the shape of every epidemiological study The GATE frame © the shape of every epidemiological study

GATE study design (PECOT)

GATE study analyses (EGO & CGO) EG CG a b c d

GATE study appraisal (RAMBO) Recruitment Allocation E C Maintenance Blind or Objective measurements & processes O T

GATE study design (PECOT) Participants Exposure Group Comparison Group E C Outcomes O Time T

Participants Study Setting Eligible Participants P Participants

Exposure & Comparison Groups Exposure or Intervention Group (EG) Comparison or Control Group (CG) EG CG

Outcomes (O) a b c d yes no ‘Dis-ease’ O Outcomes (O)

Time (T) incidence T prevalence

GATE study analyses

O = N÷D D Denominator (Participants) Numerator (Outcomes) All epidemiological studies involve measuring the OCCURRENCE of disease Occurrence = Numerator ÷ Denominator Denominator (Participants) D O = N÷D N Numerator (Outcomes)

GATE study analyses P O Overall Denominator Denominator 1: Exposure Group EG Denominator 2: Comparison Group CG EG CG Numerator 1: a Numerator 2: b a b c d O

Occurrence = N ÷ D P O Denominator 1: Exposure Group EG Denominator 2: Comparison Group CG EG CG Numerator 1: a Numerator 2: b a b c d O Exposure Group Occurrence: EGO = a ÷ EG Comparison Group Occurrence: CGO = b ÷ CG

Estimating effects & associations involves comparing occurrences Relative Effect or Risk = EGO ÷ CGO e.g. relative risk (RR), risk ratio, prevalence ratio, incidence ratio Absolute Effect or Risk Difference = EGO - CGO e.g. risk difference (RD), absolute risk Number Needed To Treat (NNT) = 1 ÷ RD

Analyses it’s all about EGO & CGO

Occurrence = N÷D per unit of time Denominator 1: Exposure Group EG x T Denominator 2: Comparison Group CG x T EG CG ‘person-time exposure’ Numerator 1= a a b c d Numerator 2 = b O Exposure Group Occurrence: EGO = a ÷ (EG x T) Comparison Group Occurrence: CGO = b ÷ (CG x T)

GATE study appraisal (RAMBO) Recruitment Allocation Blind or Objective measurements & processes E C Maintenance O T

Study appraisal How well was the study done? Was it ok ( or +) or not ok ()? or unclear (?) or not applicable (n/a) ‘no study is perfect!’

RAMBO appropriate Recruitment? participants representative of target population P Study setting & eligibility criteria well described? Recruit random sample OR Recruit consecutive eligibles E C O T ‘appropriateness’ depends on study question

appropriate Allocation process? RAMBO P appropriate Allocation process? were EG & CG comparable Allocation process well described? If allocated by investigators: Allocated randomly (e.g drugs) AND Concealed allocation OR If allocated by measurement (e.g. smoking): Adjusted for differences between EG & CG (e.g. statistical or matching) Allocate EG CG O T

P P RCT: Allocate randomly by investigators (e.g drugs) Cohort: Allocate by measurement (e.g. smoking) EG CG EG CG O O T T

did participants remain in allocated groups (EG & CG) RAMBO P good Maintenance? did participants remain in allocated groups (EG & CG) EG CG Participants &/or investigators blind to exposure (and comparison exposure)? Compliance high & similar in EG & CG Contamination low & similar in EG & CG Co-interventions low & similar in EG & CG Completeness of follow-up high & similar in EG & CG O T

measurements & processes RAMBO P Blind or Objective? measurements & processes A Allocation concealed (blind) if randomised EG & CG measurements well described Outcome measurements well described Allocation/Measurement process similar for all participants If measurement not objective (eg. automated or definitive) were assessors blind to exposure (and comparison exposure) EG CG O T

The GATE approach: every epidemiological study hangs on the GATE frame There is only one basic study design: Cohort (& case-control) studies - aetiology / prognosis / intervention RCT (a randomised cohort study)- interventions Cross-sectional studies - diagnosis

Cohort (follow-up) study: archetypal epidemiological approach Participants Allocated by measurement (not by randomisation) Exposure Group E C Comparison Group Outcomes O Time T Best design for investigating aetiology (risk), prognosis

Randomised controlled trial - cohort study where exposure allocated by randomisation process Participants Allocated by randomisation Exposure Group E C Comparison Group Outcomes O Time T Best design for investigating treatments

Case series is a Cohort study with no comparison group Participants Allocated by measurement Exposure Group E C Outcomes O Time T

Before-after study P C E O T Participants Allocated by timing of intervention C Comparison Group Exposure Group E Outcomes O Time T

Cross-over trial P E1 C2 E2 C1 O T Participants Allocated by randomisation Exposure Group 1 E1 C2 Comparison Group 2 Exposure Group 2 E2 C1 Comparison Group 1 Outcomes O Time T

Cross-sectional study real-life time P Participants Allocated by measurement Exposure Group E C Comparison Group Outcomes O Time T best design for prevalence and diagnostic test accuracy

Diagnostic test accuracy study P Disease +ve EG CG Disease -ve + a b c d Test O - Likelihood +ve test if D+ve: EGO = a ÷ EG Likelihood +ve test if D -ve: CGO = a ÷ CG

Diagnostic test accuracy study P Disease +ve EG CG Disease -ve + a b c d Test O - Likelihood -ve test if D+ve: EGO = c ÷ EG Likelihood -ve test if D -ve: CGO = d ÷ CG

Diagnostic test for disease prediction Test +ve EG CG Test -ve + a b c d Disease O - Likelihood of D if test +ve: EGO = a ÷ EG Likelihood of no D if test -ve CGO = d ÷ CG Positive predictive value Negative predictive value

Diagnosis: test accuracy P Disease + EG CG - + Diagnosis: test accuracy + a b c d CG EG O P - + - - Test

Diagnosis: test accuracy P Disease + EG CG - + Diagnosis: test accuracy + a b c d CG EG O P - + - - Test Diagnosis: disease prediction

Case control study a b c d Exposed Not Exposed Cases Controls for investigating aetiology, interventions when outcomes rare

Case control study P controls cases O T a b Participants ‘nested in a virtual cohort study’ Exp. Not Exp. Cases a b Controls P Participants controls eg cg Comparison Group Exp Group EG CG cases a b O Time T Outcomes

GATE: multiple categories Participants P C Comparison Multiple Exposure categories E1 E2 E3 Multiple Outcome categories

GATE: continuous measurements Participants 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

Life is a non-randomised trial

The 6 steps of EBP ASK a focussed question ACCESS - search for epidemiological evidence to help answer question APPRAISE the evidence for its validity, effect size, precision) AGGREGATE the evidence with patient/community, clinical/hlth & policy issues & make an evidence-based decision APPLY your decision AUDIT your practice (i.e. check your actual practice against evidence-based practice). A CAT documents the steps for a specific question

Download from www.epiq.co.nz CATS Download from www.epiq.co.nz

GATE-lite