What is evidence-based practice (EBP)? Evidence ways of knowing Practitioner Policy Patient
Practitioner Policy Patient What is evidence-based practice? Evidence ways of knowing
n more comprehensively (systematic reviews) n more critically (evidence appraisals) n more quantitatively (probabilities) using more evidence from clinical epidemiology (on diagnosis, prognosis & interventions) to inform decisions What is evidence-based practice?
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
Epidemiological evidence is the cornerstone of EBP understanding epidemiological study design is the essential skill for teachers of EBP
The 4 (5) steps of EBP 1.Ask a focussed clinical question 2.Search for appropriate epidemiological evidence to help answer question 3.Appraise (critically) the evidence (validity, impact, precision) 4.Synthesise the evidence with patient, clinical & policy issues; then apply (i.e. answer question) 5.Assess/ evaluate practice (clinical audit). Modified from DS et al
CATs: Critically Appraised Topics: a tool for modeling the steps of EBP
GATE: Graphic Appraisal Tool for Epidemiology 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.
Participant Population: Source Population: Eligible Population: 68,561 women screened from 20 outpatients/community screening centres all eligibles invited (2763) Post-menopausal, established CHD, < 80 yrs, no MI in last 6 mths, no HRT last 3 months P
GATE: occurrence HERS Exp. Group Occurrence EGO = A / EGxT = 172/1380 x 4.1 = 30.40/1000/yr Comp. Group Occurrence CGO = B / CGxT = 176/1383 x 4.1 = 31.04/1000/yr P= 2763 A= 172 EG= 1380 CG= 1383 B= 176 T= 4.1 yrs
Occurrence EGO = Exposure Group Occurrence (A/[EGxT]) CGO = Comparison Group Occurrence (B/[CGxT] = / 1000 persons / year
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
Using GATE to frame all the steps of EBP
STEP 1: Ask focussed 5-part questions: 1. P articipants (patient/population group) 2. E xposure (intervention if about therapy) 3. C omparison (there is always an alternative!) 4. O utcome 5. T imeframe
STEP 2: Search for best evidence using 3/4-part search terms: 1. P articipants (patient/population group) 2. E xposure (intervention if about therapy) 3. C omparison (e.g placebo) 4. O utcome