Research Design: The Progression of

Study Designs that Address

a Clinical Question

Edward P. Sloan, MD, MPH

Associate ProfessorDept of Emergency Medicine

University of Illinois College of Medicine

Chicago, IL

Attending Physician Emergency Medicine

University of Illinois Hospital

Our Lady of the Resurrection

Medical Center

OverviewGlobal Objectives

• Answer clinical questions

• Minimize work

• Get it done

OverviewSession Objectives

• Know what options exist

• Examine the progression of designs

• Understand the linkage and rationale

Study Types

•Case report

•Case series

•Case-control study

• Prospective observational

• Prospective randomized

Case Report

• That was an interesting case…

•Why did that happen?

• That’s unusual.

• I’ll never do that again!

Case Report

•One patient

•An important observation

•A unique teaching point

Case Series

• Is this really unusual?

•Are there similar patients?

• Is there a trend?

• Should we look further?

Case Series

• Strengthens observation

• Identifies trends

• Suggests relationships

• Supports case-control study

• Supports prospective work

Case-Control Study

•Are the unusual pts different?

•What risk factors differ?

• Is it something we can change?

• Should we look further?

Case-Control Study

• Tests associations

•Utilizes diseased, OK patients

•May be last necessary step

• Supports prospective work

Prospective Observational

•What data was missing?

•Do we need consistent data?

•What do we wish to know?

•What about missing pts?

Prospective Observational

•Consistent data

•No missing patients

•Details future interventions

• Supports clinical changes

Prospective Interventional

•Now let’s compare 2 groups…•Who will do better?•Which way should we do it?•Can we improve outcomes,

reduce costs, enhance access?

Prospective Interventional

•Best research

•Costly, but complete

•Answers the questions

•Always causes new questions to be asked

A Real Life Example

•Abdominal trauma

• Peritoneal blood

• Is there an injury?

• Is an operation needed?

• Is there a better way?