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 1Controlled Trials

WithoutRandomization

1-TYPES OF STUDY DESIGNS

Intervention Prospective Random method Experimental and control groups

RANDOMIZED CONTROLLED TRIALS (RCT)

1-TYPES OF STUDY DESIGNS

CONTROLLED TRIALS WITHOUT RANDOMIZATION

Intervention Prospective No randomization Experimental & control groups

1-TYPES OF STUDY DESIGNSB-OBSERVATIONAL STUDIES

Observational Studies

Level II-2aCOHORT

(Relative Risk)

Level II-2bCASE CONTROL

(Odds Ratio)Level II-3 Level III

1-TYPES OF STUDY DESIGNSCOHORT 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 DESIGNSCASE 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 DESIGNSCROSS 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 DESIGNSEXPERT OPINION

Findings from expert panels and committees and the opinions of respected experts in a particular field

1-TYPES OF STUDY DESIGNSA, B, C-OTHERS

Other Studies

Decision Analysis Meta-Analysis Cost EffectivenessCost-Benefit

1-TYPES OF STUDY DESIGNS

Decision Tree, branches are key problems or decisions Driven by key assumptions

DECISION ANALYSIS

DECISION ANALYSIS

Hysterectomy

Total

Subtotal

Op compl

UneventfulUneventful

Op compl

DeathL/T dis

Cure

Death

L/T dis

Cure

CureCureHysterectomy

TotalOperative complications

Death

Long Term disability

Cure

Cure

Cure

Cure

Death

Uneventful

Uneventful

Subtotal

Operative complicationsLong Term disability

META-ANALYSIS

Effect on endometrial cancer: smoking vs. no smoking

Weighted average of a variable/intervention on a defined outcome

•Beers•Dipalo•Henry•Zo

1-TYPES OF STUDY DESIGNS

Dipalo

Henry

Zo

1-TYPE OF DESIGN STUDIESCOST-BENEFIT ANALYSIS

Compares costs associated with an intervention with the net monetary benefits from the use of that intervention

1-TYPES OF STUDY DESIGNSCOST-EFFECTIVENESS ANALYSIS

Compares the net monetary costs of an intervention with some measure of clinical outcome

2-RECOMMENDATIONSBASED ON QUALITY & QUANTITY OF EVIDENCE

Recommendations

A B EC D

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