SlideShare uma empresa Scribd logo
1 de 27
Baixar para ler offline
Ashok S Gavaskar
Asst. Editor - Indian Journal of Orthopaedics
Retrospective
study design
How to set it up?
Research workshop - IOACON’ 16
Retrospective study - design
• most common form of analysis
(Data originally collected for other reasons)
• quick
• not expensive
• rare outcomes
• long latent period
• generates hypothesis
• Bias
• Cannot provide valid solutions
`
Outcome
-measurable parameter of clinical interest
“Has already occurred”
Retrospective design: Key points
Retrospective design: Key points
Exposure: ‘Factor of interest’

Interventional (can only be prospective)
you control the factor of interest
Observational (prospective/retrospective)
“you just observe”
Retrospective design: Key points
Cross-sectional
Cohort
Case control
Observational
(retrospective)
Cross sectional design
No direction

One time

(eg: Survey)
1
3
2
Different groups
compared at
ONE time
• Descriptive purposes

(states the problem)

• Poor inference
Case control design
Unexposed
Exposed
Exposed
Unexposed
DISEASE

(cases)
DISEASE

(controls)
Review

records
Review

records
• Rare outcome

(only one outcome)

• Multiple exposures

• Inference - moderate
Cohort design
Unexposed
Exposed
outcomes

(study begins)
records

review
Disease
NoDisease
Disease
NoDisease
• common outcomes

(multiple outcomes)

• Multiple exposures

• Strongest - Observational
Doing a good retrospective study
Research Question
• Description
• Relationship
• Comparison
what is going on? (incidence/prevalence research)
proportion/percentage/ central tendency/ variability
how phenomena are related?
correlation co-efficients
variable of interest (difference among groups)
central tendency
Literature review
• An essential pre-requisite

• Systematic review

(study’s area of focus, demographics, criteria)

• Multiple databases

• Background - key concepts & variables
Study proposal
• abstract

• introduction

• research question

• literature review

• methodology

• significance

• limitations

• budget

• references

Sample
Design
Variables
Instruments
Key elements: Sampling issues
• Sample size
• Sampling strategy
• Key element in any research proposal
Sample size
• Power analysis

(probability of rejecting the null hypothesis)

related to sample size

(10 cases per variable)

Tools:

• textbooks
• journal articles
• downloadable software programs (G*Power 3.0)
Sampling strategy
• Convenience sampling
what is available at disposal (e.g:cases with in a particular time frame)
• rare cases, outcomes
• small sample size
Sampling strategy
Gold standard, (has equal chance)
• suitable for multi-centre trials
• common disorders
• Random sampling
Sampling strategy
every nth case is selected (not truly random)
access to large number of records
• Systematic sampling
Study proposal
• abstract

• introduction

• research question

• literature review

• methodology

• significance

• limitations

• budget

• references

• Future prospective studies
• Variables
Define
Operationalise (literature review)
translating a construct to its
manifestation
Study proposal
• Design
• flow of information
• go through a few charts
• on site clinicians (multi-centre)
• abstract

• introduction

• research question

• literature review

• methodology

• significance

• limitations

• budget

• references
Methodology
• Instruments (paper/digital)
Paper
cost effective
pre-printed form
(avoids coder’s interpretation of data)
not so good…..

• Handwriting

• storage

• maintenance
Methodology
• Instruments
• Digital
• large RCRs
• centralisation of data storage
• entry and transcription errors
• can be generated from software packages
Data abstraction
Inclusion/ Exclusion criteria
• lack of sufficient variables recorded
• presence of excessive/confounding co-
morbidities
• confounding factors that can degrade the
validity of data
Constant review to assess excluded data
Data abstraction
• Coding/procedure manual

to ensure accuracy, reliability & consistency of data

• clear definitions

• protocols

• steps for data extraction
Data abstraction
• Data abstractors:

• selection & training

• blinding

reviewer bias

• Intra and inter -rater reliability
Data abstraction
• Intra & Inter rater reliability
• (statistical estimate to report
consistency in coding)
Inter:
Cohen kappa
(extent of agreement
-1 to +1, for RCR: 0.6)
Intra:
calculating ICC (intra class correlation)
Data management
• Data management
Software package
(Microsoft access, Medquest)
• data input

• statistics

• reporting
Pilot study
• Very useful
helps to assess
study design
feasibility
evaluate methodology
• 10% of the target population
Summary
• Well defined research questions
• Sampling: size & strategy
• Operationalise variables
• Data abstraction process: most important
• Inclusion and exclusion criteria
• Observer reliability
• Pilot test
For a good RCR…

Mais conteúdo relacionado

Mais procurados (20)

Sample size calculations
Sample size calculationsSample size calculations
Sample size calculations
 
Types of bias
Types of biasTypes of bias
Types of bias
 
Randomized Controlled Trials
Randomized Controlled TrialsRandomized Controlled Trials
Randomized Controlled Trials
 
Observational analytical and interventional studies
Observational analytical and interventional studiesObservational analytical and interventional studies
Observational analytical and interventional studies
 
Biases in epidemiology
Biases in epidemiologyBiases in epidemiology
Biases in epidemiology
 
Bias in Research
Bias in ResearchBias in Research
Bias in Research
 
Case control study
Case control studyCase control study
Case control study
 
Case control & cohort study
Case control & cohort studyCase control & cohort study
Case control & cohort study
 
3. descriptive study
3. descriptive study3. descriptive study
3. descriptive study
 
CASE CONTROL STUDY
CASE CONTROL STUDYCASE CONTROL STUDY
CASE CONTROL STUDY
 
P value
P valueP value
P value
 
Critical appraisal
Critical appraisalCritical appraisal
Critical appraisal
 
Writing of Research protocol
Writing of Research protocol Writing of Research protocol
Writing of Research protocol
 
Overview of systematic review and meta analysis
Overview of systematic review and meta  analysisOverview of systematic review and meta  analysis
Overview of systematic review and meta analysis
 
Systematic review
Systematic reviewSystematic review
Systematic review
 
Cross sectional study-dr.wah
Cross sectional study-dr.wahCross sectional study-dr.wah
Cross sectional study-dr.wah
 
Study designs
Study designsStudy designs
Study designs
 
Nested case control study
Nested case control studyNested case control study
Nested case control study
 
Cohort Study
Cohort StudyCohort Study
Cohort Study
 
Bias and errors
Bias and errorsBias and errors
Bias and errors
 

Destaque

Study Design - Retrospective cohort study
Study Design - Retrospective cohort studyStudy Design - Retrospective cohort study
Study Design - Retrospective cohort studyDr.Bharat Kalidindi
 
Clinical Evidence in the Surgical Treatment of Advanced Osteoarthritis Knee
Clinical Evidence in the Surgical Treatment of  Advanced Osteoarthritis KneeClinical Evidence in the Surgical Treatment of  Advanced Osteoarthritis Knee
Clinical Evidence in the Surgical Treatment of Advanced Osteoarthritis Kneeorthoprinciples
 
A prospective study of the short term treatment angle ortho-2005
A prospective study of the short term treatment angle ortho-2005A prospective study of the short term treatment angle ortho-2005
A prospective study of the short term treatment angle ortho-2005Indian dental academy
 
Evidence in foot and ankle surgery
Evidence in foot and ankle surgeryEvidence in foot and ankle surgery
Evidence in foot and ankle surgeryorthoprinciples
 
David Lim Crisis Communication Strategies Lessons From Everest World Continui...
David Lim Crisis Communication Strategies Lessons From Everest World Continui...David Lim Crisis Communication Strategies Lessons From Everest World Continui...
David Lim Crisis Communication Strategies Lessons From Everest World Continui...BCM Institute
 
A Framework For Effective Leadership For 1 1 Schools
A Framework For Effective Leadership For 1 1 SchoolsA Framework For Effective Leadership For 1 1 Schools
A Framework For Effective Leadership For 1 1 Schoolsfridayinstitute
 
Understanding People Instinct, Motivation and Developing Team Work
Understanding People Instinct, Motivation and Developing Team WorkUnderstanding People Instinct, Motivation and Developing Team Work
Understanding People Instinct, Motivation and Developing Team WorkKanishka Samarasinghe
 
Concept Design Study and Research Brief
Concept Design Study and Research Brief Concept Design Study and Research Brief
Concept Design Study and Research Brief PTC
 
Study Design Tridandapani 2016
Study Design Tridandapani 2016Study Design Tridandapani 2016
Study Design Tridandapani 2016evadew1
 
cohort study
cohort studycohort study
cohort studybunu lama
 
The art of the retrospective
The art of the retrospectiveThe art of the retrospective
The art of the retrospectiveAgileee
 
Sgin2013 scrumfromthe trenches-applicationoftheagileretrospectivetechniquesin...
Sgin2013 scrumfromthe trenches-applicationoftheagileretrospectivetechniquesin...Sgin2013 scrumfromthe trenches-applicationoftheagileretrospectivetechniquesin...
Sgin2013 scrumfromthe trenches-applicationoftheagileretrospectivetechniquesin...India Scrum Enthusiasts Community
 
Principles of continuous improvement and Agile retrospectives by Vedran Nikolic
Principles of continuous improvement and Agile retrospectives by Vedran NikolicPrinciples of continuous improvement and Agile retrospectives by Vedran Nikolic
Principles of continuous improvement and Agile retrospectives by Vedran NikolicBosnia Agile
 
Behind the scenes of retrospective workshop-goat16-november 21th-2016-hand-out
Behind the scenes of retrospective workshop-goat16-november 21th-2016-hand-outBehind the scenes of retrospective workshop-goat16-november 21th-2016-hand-out
Behind the scenes of retrospective workshop-goat16-november 21th-2016-hand-outJesus Mendez
 
Why Should You Retrospect? An Agile Story
Why Should You Retrospect? An Agile StoryWhy Should You Retrospect? An Agile Story
Why Should You Retrospect? An Agile StoryGeorge Psistakis
 

Destaque (20)

Study Design - Retrospective cohort study
Study Design - Retrospective cohort studyStudy Design - Retrospective cohort study
Study Design - Retrospective cohort study
 
Clinical Evidence in the Surgical Treatment of Advanced Osteoarthritis Knee
Clinical Evidence in the Surgical Treatment of  Advanced Osteoarthritis KneeClinical Evidence in the Surgical Treatment of  Advanced Osteoarthritis Knee
Clinical Evidence in the Surgical Treatment of Advanced Osteoarthritis Knee
 
A prospective study of the short term treatment angle ortho-2005
A prospective study of the short term treatment angle ortho-2005A prospective study of the short term treatment angle ortho-2005
A prospective study of the short term treatment angle ortho-2005
 
Evidence in foot and ankle surgery
Evidence in foot and ankle surgeryEvidence in foot and ankle surgery
Evidence in foot and ankle surgery
 
7-Cohort Studies
7-Cohort Studies7-Cohort Studies
7-Cohort Studies
 
David Lim Crisis Communication Strategies Lessons From Everest World Continui...
David Lim Crisis Communication Strategies Lessons From Everest World Continui...David Lim Crisis Communication Strategies Lessons From Everest World Continui...
David Lim Crisis Communication Strategies Lessons From Everest World Continui...
 
A Framework For Effective Leadership For 1 1 Schools
A Framework For Effective Leadership For 1 1 SchoolsA Framework For Effective Leadership For 1 1 Schools
A Framework For Effective Leadership For 1 1 Schools
 
Understanding People Instinct, Motivation and Developing Team Work
Understanding People Instinct, Motivation and Developing Team WorkUnderstanding People Instinct, Motivation and Developing Team Work
Understanding People Instinct, Motivation and Developing Team Work
 
Concept Design Study and Research Brief
Concept Design Study and Research Brief Concept Design Study and Research Brief
Concept Design Study and Research Brief
 
Study Design Tridandapani 2016
Study Design Tridandapani 2016Study Design Tridandapani 2016
Study Design Tridandapani 2016
 
Study design of Prof Zak
Study design of Prof ZakStudy design of Prof Zak
Study design of Prof Zak
 
cohort study
cohort studycohort study
cohort study
 
The art of the retrospective
The art of the retrospectiveThe art of the retrospective
The art of the retrospective
 
Sgin2013 scrumfromthe trenches-applicationoftheagileretrospectivetechniquesin...
Sgin2013 scrumfromthe trenches-applicationoftheagileretrospectivetechniquesin...Sgin2013 scrumfromthe trenches-applicationoftheagileretrospectivetechniquesin...
Sgin2013 scrumfromthe trenches-applicationoftheagileretrospectivetechniquesin...
 
Principles of continuous improvement and Agile retrospectives by Vedran Nikolic
Principles of continuous improvement and Agile retrospectives by Vedran NikolicPrinciples of continuous improvement and Agile retrospectives by Vedran Nikolic
Principles of continuous improvement and Agile retrospectives by Vedran Nikolic
 
Behind the scenes of retrospective workshop-goat16-november 21th-2016-hand-out
Behind the scenes of retrospective workshop-goat16-november 21th-2016-hand-outBehind the scenes of retrospective workshop-goat16-november 21th-2016-hand-out
Behind the scenes of retrospective workshop-goat16-november 21th-2016-hand-out
 
Bearing surfaces
Bearing surfacesBearing surfaces
Bearing surfaces
 
Why Should You Retrospect? An Agile Story
Why Should You Retrospect? An Agile StoryWhy Should You Retrospect? An Agile Story
Why Should You Retrospect? An Agile Story
 
Facebook retrospective
Facebook retrospectiveFacebook retrospective
Facebook retrospective
 
5. cohort studies
5. cohort  studies5. cohort  studies
5. cohort studies
 

Semelhante a Retrospective Study Design

ITFT - Types of research designs
ITFT - Types of research designsITFT - Types of research designs
ITFT - Types of research designsDrSmitiJhajj
 
Types of research designs
Types of research designsTypes of research designs
Types of research designsWalaa Abdelnaby
 
Types of research designs 2
Types of research designs 2Types of research designs 2
Types of research designs 2Mathew Ngugi
 
types of research designs.ppt
types of research designs.ppttypes of research designs.ppt
types of research designs.pptbiruktesfaye27
 
Types of research designs
Types of research designsTypes of research designs
Types of research designssunilkumar5563
 
Introduction to systematic reviews
Introduction to systematic reviewsIntroduction to systematic reviews
Introduction to systematic reviewsOmar Midani
 
RESEARCH DESIGN
RESEARCH DESIGNRESEARCH DESIGN
RESEARCH DESIGNDrRachna6
 
STEPS IN RESEARCH
STEPS IN RESEARCHSTEPS IN RESEARCH
STEPS IN RESEARCHVineetha K
 
Introduction To Research Methodology
Introduction To Research MethodologyIntroduction To Research Methodology
Introduction To Research MethodologyMero Eye
 
How to write a research proposal
How to write a research proposalHow to write a research proposal
How to write a research proposalDrHebatalla Mohamed
 
Critical appraisal of a journal article
Critical appraisal of a journal articleCritical appraisal of a journal article
Critical appraisal of a journal articleDrSahilKumar
 
Research protocol writting
Research protocol writtingResearch protocol writting
Research protocol writtingDawal Salve
 
Concept of research design
Concept of research designConcept of research design
Concept of research designPrabesh Ghimire
 
Systematic review my presentation.pptx
Systematic review my presentation.pptxSystematic review my presentation.pptx
Systematic review my presentation.pptxnehalabosamra91
 
Research Proposal.pptx
Research Proposal.pptxResearch Proposal.pptx
Research Proposal.pptxKareem868098
 

Semelhante a Retrospective Study Design (20)

ITFT - Types of research designs
ITFT - Types of research designsITFT - Types of research designs
ITFT - Types of research designs
 
Types of research designs
Types of research designsTypes of research designs
Types of research designs
 
Types of research designs 2
Types of research designs 2Types of research designs 2
Types of research designs 2
 
types of research designs.ppt
types of research designs.ppttypes of research designs.ppt
types of research designs.ppt
 
Types of research designs
Types of research designsTypes of research designs
Types of research designs
 
Introduction to systematic reviews
Introduction to systematic reviewsIntroduction to systematic reviews
Introduction to systematic reviews
 
Research methodology
Research methodologyResearch methodology
Research methodology
 
Systematic Literature Review
Systematic Literature ReviewSystematic Literature Review
Systematic Literature Review
 
RESEARCH DESIGN
RESEARCH DESIGNRESEARCH DESIGN
RESEARCH DESIGN
 
STEPS IN RESEARCH
STEPS IN RESEARCHSTEPS IN RESEARCH
STEPS IN RESEARCH
 
Introduction To Research Methodology
Introduction To Research MethodologyIntroduction To Research Methodology
Introduction To Research Methodology
 
Research Design.pptx
Research Design.pptxResearch Design.pptx
Research Design.pptx
 
How to write a research proposal
How to write a research proposalHow to write a research proposal
How to write a research proposal
 
Critical appraisal of a journal article
Critical appraisal of a journal articleCritical appraisal of a journal article
Critical appraisal of a journal article
 
Research methodology
Research methodologyResearch methodology
Research methodology
 
Research protocol writting
Research protocol writtingResearch protocol writting
Research protocol writting
 
Concept of research design
Concept of research designConcept of research design
Concept of research design
 
Research methodology
Research methodologyResearch methodology
Research methodology
 
Systematic review my presentation.pptx
Systematic review my presentation.pptxSystematic review my presentation.pptx
Systematic review my presentation.pptx
 
Research Proposal.pptx
Research Proposal.pptxResearch Proposal.pptx
Research Proposal.pptx
 

Mais de orthoprinciples

Radial head replacement best evidence
Radial head replacement best evidenceRadial head replacement best evidence
Radial head replacement best evidenceorthoprinciples
 
External fixation in open tibial fractures best evidence
External fixation in open tibial fractures best evidenceExternal fixation in open tibial fractures best evidence
External fixation in open tibial fractures best evidenceorthoprinciples
 
Management of Multiple myeloma
Management of Multiple myelomaManagement of Multiple myeloma
Management of Multiple myelomaorthoprinciples
 
Acl graft fixation options
Acl graft fixation optionsAcl graft fixation options
Acl graft fixation optionsorthoprinciples
 
Alternative bearing surfaces
Alternative bearing surfaces  Alternative bearing surfaces
Alternative bearing surfaces orthoprinciples
 

Mais de orthoprinciples (7)

Radial head replacement best evidence
Radial head replacement best evidenceRadial head replacement best evidence
Radial head replacement best evidence
 
External fixation in open tibial fractures best evidence
External fixation in open tibial fractures best evidenceExternal fixation in open tibial fractures best evidence
External fixation in open tibial fractures best evidence
 
Ramesh Sen AVN
Ramesh Sen AVNRamesh Sen AVN
Ramesh Sen AVN
 
Management of Multiple myeloma
Management of Multiple myelomaManagement of Multiple myeloma
Management of Multiple myeloma
 
Terrible Triad of Elbow
Terrible Triad of ElbowTerrible Triad of Elbow
Terrible Triad of Elbow
 
Acl graft fixation options
Acl graft fixation optionsAcl graft fixation options
Acl graft fixation options
 
Alternative bearing surfaces
Alternative bearing surfaces  Alternative bearing surfaces
Alternative bearing surfaces
 

Último

Call Girls Bhubaneswar Just Call 9907093804 Top Class Call Girl Service Avail...
Call Girls Bhubaneswar Just Call 9907093804 Top Class Call Girl Service Avail...Call Girls Bhubaneswar Just Call 9907093804 Top Class Call Girl Service Avail...
Call Girls Bhubaneswar Just Call 9907093804 Top Class Call Girl Service Avail...Dipal Arora
 
Top Rated Bangalore Call Girls Mg Road ⟟ 8250192130 ⟟ Call Me For Genuine Sex...
Top Rated Bangalore Call Girls Mg Road ⟟ 8250192130 ⟟ Call Me For Genuine Sex...Top Rated Bangalore Call Girls Mg Road ⟟ 8250192130 ⟟ Call Me For Genuine Sex...
Top Rated Bangalore Call Girls Mg Road ⟟ 8250192130 ⟟ Call Me For Genuine Sex...narwatsonia7
 
(Rocky) Jaipur Call Girl - 09521753030 Escorts Service 50% Off with Cash ON D...
(Rocky) Jaipur Call Girl - 09521753030 Escorts Service 50% Off with Cash ON D...(Rocky) Jaipur Call Girl - 09521753030 Escorts Service 50% Off with Cash ON D...
(Rocky) Jaipur Call Girl - 09521753030 Escorts Service 50% Off with Cash ON D...indiancallgirl4rent
 
VIP Mumbai Call Girls Hiranandani Gardens Just Call 9920874524 with A/C Room ...
VIP Mumbai Call Girls Hiranandani Gardens Just Call 9920874524 with A/C Room ...VIP Mumbai Call Girls Hiranandani Gardens Just Call 9920874524 with A/C Room ...
VIP Mumbai Call Girls Hiranandani Gardens Just Call 9920874524 with A/C Room ...Garima Khatri
 
Top Rated Hyderabad Call Girls Erragadda ⟟ 6297143586 ⟟ Call Me For Genuine ...
Top Rated  Hyderabad Call Girls Erragadda ⟟ 6297143586 ⟟ Call Me For Genuine ...Top Rated  Hyderabad Call Girls Erragadda ⟟ 6297143586 ⟟ Call Me For Genuine ...
Top Rated Hyderabad Call Girls Erragadda ⟟ 6297143586 ⟟ Call Me For Genuine ...chandars293
 
Call Girls Service Jaipur Grishma WhatsApp ❤8445551418 VIP Call Girls Jaipur
Call Girls Service Jaipur Grishma WhatsApp ❤8445551418 VIP Call Girls JaipurCall Girls Service Jaipur Grishma WhatsApp ❤8445551418 VIP Call Girls Jaipur
Call Girls Service Jaipur Grishma WhatsApp ❤8445551418 VIP Call Girls Jaipurparulsinha
 
Call Girls Varanasi Just Call 9907093804 Top Class Call Girl Service Available
Call Girls Varanasi Just Call 9907093804 Top Class Call Girl Service AvailableCall Girls Varanasi Just Call 9907093804 Top Class Call Girl Service Available
Call Girls Varanasi Just Call 9907093804 Top Class Call Girl Service AvailableDipal Arora
 
Call Girls Faridabad Just Call 9907093804 Top Class Call Girl Service Available
Call Girls Faridabad Just Call 9907093804 Top Class Call Girl Service AvailableCall Girls Faridabad Just Call 9907093804 Top Class Call Girl Service Available
Call Girls Faridabad Just Call 9907093804 Top Class Call Girl Service AvailableDipal Arora
 
Call Girls Service Surat Samaira ❤️🍑 8250192130 👄 Independent Escort Service ...
Call Girls Service Surat Samaira ❤️🍑 8250192130 👄 Independent Escort Service ...Call Girls Service Surat Samaira ❤️🍑 8250192130 👄 Independent Escort Service ...
Call Girls Service Surat Samaira ❤️🍑 8250192130 👄 Independent Escort Service ...CALL GIRLS
 
Call Girls Bareilly Just Call 9907093804 Top Class Call Girl Service Available
Call Girls Bareilly Just Call 9907093804 Top Class Call Girl Service AvailableCall Girls Bareilly Just Call 9907093804 Top Class Call Girl Service Available
Call Girls Bareilly Just Call 9907093804 Top Class Call Girl Service AvailableDipal Arora
 
Bangalore Call Girl Whatsapp Number 100% Complete Your Sexual Needs
Bangalore Call Girl Whatsapp Number 100% Complete Your Sexual NeedsBangalore Call Girl Whatsapp Number 100% Complete Your Sexual Needs
Bangalore Call Girl Whatsapp Number 100% Complete Your Sexual NeedsGfnyt
 
Best Rate (Guwahati ) Call Girls Guwahati ⟟ 8617370543 ⟟ High Class Call Girl...
Best Rate (Guwahati ) Call Girls Guwahati ⟟ 8617370543 ⟟ High Class Call Girl...Best Rate (Guwahati ) Call Girls Guwahati ⟟ 8617370543 ⟟ High Class Call Girl...
Best Rate (Guwahati ) Call Girls Guwahati ⟟ 8617370543 ⟟ High Class Call Girl...Dipal Arora
 
Night 7k to 12k Chennai City Center Call Girls 👉👉 7427069034⭐⭐ 100% Genuine E...
Night 7k to 12k Chennai City Center Call Girls 👉👉 7427069034⭐⭐ 100% Genuine E...Night 7k to 12k Chennai City Center Call Girls 👉👉 7427069034⭐⭐ 100% Genuine E...
Night 7k to 12k Chennai City Center Call Girls 👉👉 7427069034⭐⭐ 100% Genuine E...hotbabesbook
 
Book Paid Powai Call Girls Mumbai 𖠋 9930245274 𖠋Low Budget Full Independent H...
Book Paid Powai Call Girls Mumbai 𖠋 9930245274 𖠋Low Budget Full Independent H...Book Paid Powai Call Girls Mumbai 𖠋 9930245274 𖠋Low Budget Full Independent H...
Book Paid Powai Call Girls Mumbai 𖠋 9930245274 𖠋Low Budget Full Independent H...Call Girls in Nagpur High Profile
 
Best Rate (Hyderabad) Call Girls Jahanuma ⟟ 8250192130 ⟟ High Class Call Girl...
Best Rate (Hyderabad) Call Girls Jahanuma ⟟ 8250192130 ⟟ High Class Call Girl...Best Rate (Hyderabad) Call Girls Jahanuma ⟟ 8250192130 ⟟ High Class Call Girl...
Best Rate (Hyderabad) Call Girls Jahanuma ⟟ 8250192130 ⟟ High Class Call Girl...astropune
 
VIP Call Girls Indore Kirti 💚😋 9256729539 🚀 Indore Escorts
VIP Call Girls Indore Kirti 💚😋  9256729539 🚀 Indore EscortsVIP Call Girls Indore Kirti 💚😋  9256729539 🚀 Indore Escorts
VIP Call Girls Indore Kirti 💚😋 9256729539 🚀 Indore Escortsaditipandeya
 
The Most Attractive Hyderabad Call Girls Kothapet 𖠋 6297143586 𖠋 Will You Mis...
The Most Attractive Hyderabad Call Girls Kothapet 𖠋 6297143586 𖠋 Will You Mis...The Most Attractive Hyderabad Call Girls Kothapet 𖠋 6297143586 𖠋 Will You Mis...
The Most Attractive Hyderabad Call Girls Kothapet 𖠋 6297143586 𖠋 Will You Mis...chandars293
 
Call Girls Ludhiana Just Call 9907093804 Top Class Call Girl Service Available
Call Girls Ludhiana Just Call 9907093804 Top Class Call Girl Service AvailableCall Girls Ludhiana Just Call 9907093804 Top Class Call Girl Service Available
Call Girls Ludhiana Just Call 9907093804 Top Class Call Girl Service AvailableDipal Arora
 
Call Girls Jabalpur Just Call 9907093804 Top Class Call Girl Service Available
Call Girls Jabalpur Just Call 9907093804 Top Class Call Girl Service AvailableCall Girls Jabalpur Just Call 9907093804 Top Class Call Girl Service Available
Call Girls Jabalpur Just Call 9907093804 Top Class Call Girl Service AvailableDipal Arora
 

Último (20)

Call Girls Bhubaneswar Just Call 9907093804 Top Class Call Girl Service Avail...
Call Girls Bhubaneswar Just Call 9907093804 Top Class Call Girl Service Avail...Call Girls Bhubaneswar Just Call 9907093804 Top Class Call Girl Service Avail...
Call Girls Bhubaneswar Just Call 9907093804 Top Class Call Girl Service Avail...
 
Top Rated Bangalore Call Girls Mg Road ⟟ 8250192130 ⟟ Call Me For Genuine Sex...
Top Rated Bangalore Call Girls Mg Road ⟟ 8250192130 ⟟ Call Me For Genuine Sex...Top Rated Bangalore Call Girls Mg Road ⟟ 8250192130 ⟟ Call Me For Genuine Sex...
Top Rated Bangalore Call Girls Mg Road ⟟ 8250192130 ⟟ Call Me For Genuine Sex...
 
(Rocky) Jaipur Call Girl - 09521753030 Escorts Service 50% Off with Cash ON D...
(Rocky) Jaipur Call Girl - 09521753030 Escorts Service 50% Off with Cash ON D...(Rocky) Jaipur Call Girl - 09521753030 Escorts Service 50% Off with Cash ON D...
(Rocky) Jaipur Call Girl - 09521753030 Escorts Service 50% Off with Cash ON D...
 
VIP Mumbai Call Girls Hiranandani Gardens Just Call 9920874524 with A/C Room ...
VIP Mumbai Call Girls Hiranandani Gardens Just Call 9920874524 with A/C Room ...VIP Mumbai Call Girls Hiranandani Gardens Just Call 9920874524 with A/C Room ...
VIP Mumbai Call Girls Hiranandani Gardens Just Call 9920874524 with A/C Room ...
 
Top Rated Hyderabad Call Girls Erragadda ⟟ 6297143586 ⟟ Call Me For Genuine ...
Top Rated  Hyderabad Call Girls Erragadda ⟟ 6297143586 ⟟ Call Me For Genuine ...Top Rated  Hyderabad Call Girls Erragadda ⟟ 6297143586 ⟟ Call Me For Genuine ...
Top Rated Hyderabad Call Girls Erragadda ⟟ 6297143586 ⟟ Call Me For Genuine ...
 
Call Girls Service Jaipur Grishma WhatsApp ❤8445551418 VIP Call Girls Jaipur
Call Girls Service Jaipur Grishma WhatsApp ❤8445551418 VIP Call Girls JaipurCall Girls Service Jaipur Grishma WhatsApp ❤8445551418 VIP Call Girls Jaipur
Call Girls Service Jaipur Grishma WhatsApp ❤8445551418 VIP Call Girls Jaipur
 
Call Girls Varanasi Just Call 9907093804 Top Class Call Girl Service Available
Call Girls Varanasi Just Call 9907093804 Top Class Call Girl Service AvailableCall Girls Varanasi Just Call 9907093804 Top Class Call Girl Service Available
Call Girls Varanasi Just Call 9907093804 Top Class Call Girl Service Available
 
Call Girls Faridabad Just Call 9907093804 Top Class Call Girl Service Available
Call Girls Faridabad Just Call 9907093804 Top Class Call Girl Service AvailableCall Girls Faridabad Just Call 9907093804 Top Class Call Girl Service Available
Call Girls Faridabad Just Call 9907093804 Top Class Call Girl Service Available
 
Call Girls Service Surat Samaira ❤️🍑 8250192130 👄 Independent Escort Service ...
Call Girls Service Surat Samaira ❤️🍑 8250192130 👄 Independent Escort Service ...Call Girls Service Surat Samaira ❤️🍑 8250192130 👄 Independent Escort Service ...
Call Girls Service Surat Samaira ❤️🍑 8250192130 👄 Independent Escort Service ...
 
Call Girls Bareilly Just Call 9907093804 Top Class Call Girl Service Available
Call Girls Bareilly Just Call 9907093804 Top Class Call Girl Service AvailableCall Girls Bareilly Just Call 9907093804 Top Class Call Girl Service Available
Call Girls Bareilly Just Call 9907093804 Top Class Call Girl Service Available
 
Russian Call Girls in Delhi Tanvi ➡️ 9711199012 💋📞 Independent Escort Service...
Russian Call Girls in Delhi Tanvi ➡️ 9711199012 💋📞 Independent Escort Service...Russian Call Girls in Delhi Tanvi ➡️ 9711199012 💋📞 Independent Escort Service...
Russian Call Girls in Delhi Tanvi ➡️ 9711199012 💋📞 Independent Escort Service...
 
Bangalore Call Girl Whatsapp Number 100% Complete Your Sexual Needs
Bangalore Call Girl Whatsapp Number 100% Complete Your Sexual NeedsBangalore Call Girl Whatsapp Number 100% Complete Your Sexual Needs
Bangalore Call Girl Whatsapp Number 100% Complete Your Sexual Needs
 
Best Rate (Guwahati ) Call Girls Guwahati ⟟ 8617370543 ⟟ High Class Call Girl...
Best Rate (Guwahati ) Call Girls Guwahati ⟟ 8617370543 ⟟ High Class Call Girl...Best Rate (Guwahati ) Call Girls Guwahati ⟟ 8617370543 ⟟ High Class Call Girl...
Best Rate (Guwahati ) Call Girls Guwahati ⟟ 8617370543 ⟟ High Class Call Girl...
 
Night 7k to 12k Chennai City Center Call Girls 👉👉 7427069034⭐⭐ 100% Genuine E...
Night 7k to 12k Chennai City Center Call Girls 👉👉 7427069034⭐⭐ 100% Genuine E...Night 7k to 12k Chennai City Center Call Girls 👉👉 7427069034⭐⭐ 100% Genuine E...
Night 7k to 12k Chennai City Center Call Girls 👉👉 7427069034⭐⭐ 100% Genuine E...
 
Book Paid Powai Call Girls Mumbai 𖠋 9930245274 𖠋Low Budget Full Independent H...
Book Paid Powai Call Girls Mumbai 𖠋 9930245274 𖠋Low Budget Full Independent H...Book Paid Powai Call Girls Mumbai 𖠋 9930245274 𖠋Low Budget Full Independent H...
Book Paid Powai Call Girls Mumbai 𖠋 9930245274 𖠋Low Budget Full Independent H...
 
Best Rate (Hyderabad) Call Girls Jahanuma ⟟ 8250192130 ⟟ High Class Call Girl...
Best Rate (Hyderabad) Call Girls Jahanuma ⟟ 8250192130 ⟟ High Class Call Girl...Best Rate (Hyderabad) Call Girls Jahanuma ⟟ 8250192130 ⟟ High Class Call Girl...
Best Rate (Hyderabad) Call Girls Jahanuma ⟟ 8250192130 ⟟ High Class Call Girl...
 
VIP Call Girls Indore Kirti 💚😋 9256729539 🚀 Indore Escorts
VIP Call Girls Indore Kirti 💚😋  9256729539 🚀 Indore EscortsVIP Call Girls Indore Kirti 💚😋  9256729539 🚀 Indore Escorts
VIP Call Girls Indore Kirti 💚😋 9256729539 🚀 Indore Escorts
 
The Most Attractive Hyderabad Call Girls Kothapet 𖠋 6297143586 𖠋 Will You Mis...
The Most Attractive Hyderabad Call Girls Kothapet 𖠋 6297143586 𖠋 Will You Mis...The Most Attractive Hyderabad Call Girls Kothapet 𖠋 6297143586 𖠋 Will You Mis...
The Most Attractive Hyderabad Call Girls Kothapet 𖠋 6297143586 𖠋 Will You Mis...
 
Call Girls Ludhiana Just Call 9907093804 Top Class Call Girl Service Available
Call Girls Ludhiana Just Call 9907093804 Top Class Call Girl Service AvailableCall Girls Ludhiana Just Call 9907093804 Top Class Call Girl Service Available
Call Girls Ludhiana Just Call 9907093804 Top Class Call Girl Service Available
 
Call Girls Jabalpur Just Call 9907093804 Top Class Call Girl Service Available
Call Girls Jabalpur Just Call 9907093804 Top Class Call Girl Service AvailableCall Girls Jabalpur Just Call 9907093804 Top Class Call Girl Service Available
Call Girls Jabalpur Just Call 9907093804 Top Class Call Girl Service Available
 

Retrospective Study Design

  • 1. Ashok S Gavaskar Asst. Editor - Indian Journal of Orthopaedics Retrospective study design How to set it up? Research workshop - IOACON’ 16
  • 2. Retrospective study - design • most common form of analysis (Data originally collected for other reasons) • quick • not expensive • rare outcomes • long latent period • generates hypothesis • Bias • Cannot provide valid solutions
  • 3. ` Outcome -measurable parameter of clinical interest “Has already occurred” Retrospective design: Key points
  • 4. Retrospective design: Key points Exposure: ‘Factor of interest’ Interventional (can only be prospective) you control the factor of interest Observational (prospective/retrospective) “you just observe”
  • 5. Retrospective design: Key points Cross-sectional Cohort Case control Observational (retrospective)
  • 6. Cross sectional design No direction One time (eg: Survey) 1 3 2 Different groups compared at ONE time • Descriptive purposes (states the problem) • Poor inference
  • 8. Cohort design Unexposed Exposed outcomes (study begins) records review Disease NoDisease Disease NoDisease • common outcomes (multiple outcomes) • Multiple exposures • Strongest - Observational
  • 9. Doing a good retrospective study Research Question • Description • Relationship • Comparison what is going on? (incidence/prevalence research) proportion/percentage/ central tendency/ variability how phenomena are related? correlation co-efficients variable of interest (difference among groups) central tendency
  • 10. Literature review • An essential pre-requisite • Systematic review (study’s area of focus, demographics, criteria) • Multiple databases • Background - key concepts & variables
  • 11. Study proposal • abstract • introduction • research question • literature review • methodology • significance • limitations • budget • references Sample Design Variables Instruments
  • 12. Key elements: Sampling issues • Sample size • Sampling strategy • Key element in any research proposal
  • 13. Sample size • Power analysis (probability of rejecting the null hypothesis) related to sample size (10 cases per variable) Tools: • textbooks • journal articles • downloadable software programs (G*Power 3.0)
  • 14. Sampling strategy • Convenience sampling what is available at disposal (e.g:cases with in a particular time frame) • rare cases, outcomes • small sample size
  • 15. Sampling strategy Gold standard, (has equal chance) • suitable for multi-centre trials • common disorders • Random sampling
  • 16. Sampling strategy every nth case is selected (not truly random) access to large number of records • Systematic sampling
  • 17. Study proposal • abstract • introduction • research question • literature review • methodology • significance • limitations • budget • references • Future prospective studies • Variables Define Operationalise (literature review) translating a construct to its manifestation
  • 18. Study proposal • Design • flow of information • go through a few charts • on site clinicians (multi-centre) • abstract • introduction • research question • literature review • methodology • significance • limitations • budget • references
  • 19. Methodology • Instruments (paper/digital) Paper cost effective pre-printed form (avoids coder’s interpretation of data) not so good….. • Handwriting • storage • maintenance
  • 20. Methodology • Instruments • Digital • large RCRs • centralisation of data storage • entry and transcription errors • can be generated from software packages
  • 21. Data abstraction Inclusion/ Exclusion criteria • lack of sufficient variables recorded • presence of excessive/confounding co- morbidities • confounding factors that can degrade the validity of data Constant review to assess excluded data
  • 22. Data abstraction • Coding/procedure manual to ensure accuracy, reliability & consistency of data • clear definitions • protocols • steps for data extraction
  • 23. Data abstraction • Data abstractors: • selection & training • blinding reviewer bias • Intra and inter -rater reliability
  • 24. Data abstraction • Intra & Inter rater reliability • (statistical estimate to report consistency in coding) Inter: Cohen kappa (extent of agreement -1 to +1, for RCR: 0.6) Intra: calculating ICC (intra class correlation)
  • 25. Data management • Data management Software package (Microsoft access, Medquest) • data input • statistics • reporting
  • 26. Pilot study • Very useful helps to assess study design feasibility evaluate methodology • 10% of the target population
  • 27. Summary • Well defined research questions • Sampling: size & strategy • Operationalise variables • Data abstraction process: most important • Inclusion and exclusion criteria • Observer reliability • Pilot test For a good RCR…