Download EVIDENCE BASED PRACTICE

EVIDENCE BASED
PRACTICE
BY MOHEB KHOUZAM MD
EVIDENCE BASED
PRACTICE
1- TYPES OF STUDY DESIGNS
 2- RECOMMENDATIONS

EVIDENCE BASED
PRACTICE
1-TYPES OF STUDY DESIGNS
Intervention
Observational
Others
1-TYPES OF STUDY DESIGNS
A. INTERVENTION STUDIES
Intervention Study
Level I
Level II
Randomized
Controlled Trials
Level II 1
Controlled Trials
Without
Randomization
1-TYPES OF STUDY DESIGNS
RANDOMIZED CONTROLLED TRIALS (RCT)
Intervention
 Prospective
 Random method
 Experimental and control groups

1-TYPES OF STUDY DESIGNS
CONTROLLED TRIALS WITHOUT RANDOMIZATION
Intervention
 Prospective
 No randomization
 Experimental & control groups

1-TYPES OF STUDY DESIGNS
B-OBSERVATIONAL STUDIES
Observational
Studies
Level II-2a
COHORT
(Relative Risk)
Level II-2b
CASE CONTROL
(Odds Ratio)
Level II-3
Level III
1-TYPES OF STUDY DESIGNS
COHORT STUDIES



Exposure status known
Follow-up for a period of time
Determine presence or absence of disease



(i) Prospective: groups of exposed & unexposed
followed-up for a period to determine outcome
(ii) Retrospective: both exposures & outcomes occurred.
Rate of disease in exposed / Rate of disease in
unexposed gives Relative Risk
1-TYPES OF STUDY DESIGNS
CASE CONTROLLED STUDIES







Retrospective
Group of subjects with specific outcome (cases)
Group of subjects without specific outcome
(controls)
Over a period of time
Here starting point is disease status
Compare extent of exposure to a variable of
interest
Odds of exposure in cases/odd of exposure in
controls= Odds Ratio
1-TYPES OF STUDY DESIGNS
B- OBSERVATIONAL STUDY
Level II-3
Cross Sectional
(Prevalence)
Uncontrolled
Investigational
1- TYPES OF STUDY DESIGNS
CROSS SECTIONAL STUDIES
 Observational
 Assess the status of individuals with respect to
presence or absence of both exposure &
outcome at a particular time.


Prevalence is the proportion of individuals with a
disease at a particular time
Incidence is the number of new cases occurring
over a specified period of time
1-TYPES OF STUDY DESIGNS
UNCONTROLLED INVESTIGATIONAL STUDIES
Observational
 Report the results of treatment or
interventions in a particular group
 No control group

1-TYPES OF STUDY DESIGNS
B- OBSERVATIONAL STUDY
Level III
Descriptive
(Case Report/Series)
Expert Opinion
1-TYPES OF STUDY DESIGNS
DESCRIPTIVE STUDIES

Provide limited information on relationship
between exposure and outcome of interest

Case study describes clinical characteristics or
interesting features in a single patient

Case series describes the same in a series of
patients
1-TYPES OF STUDY DESIGNS
EXPERT OPINION

Findings from expert panels and
committees and the opinions of respected
experts in a particular field
1-TYPES OF STUDY DESIGNS
A, B, C-OTHERS
Other Studies
Decision Analysis
Meta-Analysis
Cost-Benefit
Cost Effectiveness
1-TYPES OF STUDY DESIGNS
DECISION ANALYSIS
DECISION ANALYSIS
Total
Operative
complications
Op compl
Total
Hysterectomy
Hysterectomy
Uneventful
Uneventful
Uneventful
Uneventful
Subtotal
Subtotal
Op compl
Operative complications
Death
Death
Longdis
Term disability
L/T
Cure
Cure
Cure
Cure
Cure
Cure
Death
Death
L/T
dis
Long
Term disability
Cure
Cure
Decision Tree, branches are key problems or decisions
Driven by key assumptions
1-TYPES OF STUDY DESIGNS

META-ANALYSIS
•Beers
Dipalo
•Dipalo
•Henry Henry
•Zo
Zo


Effect on endometrial cancer: smoking vs. no
smoking
Weighted average of a variable/intervention
on a defined outcome
1-TYPE OF DESIGN STUDIES
COST-BENEFIT ANALYSIS

Compares costs associated with an
intervention with the net monetary
benefits from the use of that intervention
1-TYPES OF STUDY DESIGNS
COST-EFFECTIVENESS ANALYSIS

Compares the net monetary costs of an
intervention with some measure of
clinical outcome
2-RECOMMENDATIONS
BASED ON QUALITY & QUANTITY OF EVIDENCE
Recommendations
A
B
C
D
E
2-RECOMMENDATIONS






A There is good evidence to support
recommendations
B There is fair evidence to support
recommendations
C There is insufficient evidence to support
recommendations, but recommendation is made
on other grounds
D There is fair evidence against
recommendations
E There is good evidence against
recommendations
There is no exact correlation between strength of
recommendations and level of evidence