drugepi 3-6 study design exercises module 3 introduction content area: analytical epidemiology...

DrugEpi 3-6 Study Design Exercises

Module 3 IntroductionContent Area: Analytical EpidemiologyEssential Question (Generic): Is there an association between the hypothesized cause and the disease?Essential Question (Drug Abuse Specific): Is there an association between the hypothesized cause and drug use?Enduring Epidemiological Understanding: Causal hypotheses can be tested by observing exposures and diseases of people as they go about their daily lives. Information from these observational studies can be used to make and compare rates and identify associations.

Synopsis

In Module 3, students explore how hypotheses are tested epidemiologically. Students begin to uncover and develop the following epidemiological concepts and skills: the meaning of the term “association;” the need for a control group; uses of the 2x2 table in calculating risks and relative risks; experimental study design; the importance of ethics in human research; observational study designs used in epidemiology; and the strengths and limitations of each design.

Lesson 3-1: Associations and the 2x2 TableLesson 3-2: Experimental Study - Buprenorphine ExampleLesson 3-3: An Actual Randomized Controlled TrialLesson 3-4: Observational Studies of Natural Experiments - Sensation-Seeking ExampleLesson 3-5: Fundamentals of Study DesignLesson 3-6: Study Design Exercises


Module 3 - Analytical Epidemiology

Lesson 3-6 Study Design Exercises

Content

• Reinforcement of study design concepts with an exercise to identify “What is My Design?”

• An Epi Team challenge that pulls together the study design elements, called “Connections between Designs, Flow Diagrams, and 2x2 Tables”

• Reinforcement of relative strengths and limitations of each study design with a key exercise that examines “Which Design is Best?”

Big Ideas

• The flow diagrams show how each study design is carried out in time

• Each study design can be expressed in a 2x2 table format that connects to the depiction in the flow diagram

• Each study design has strengths, limitations, and trade-offs. Usually, the studies with greater scientific rigor also have higher costs and time to completion. Choice of study designs depends on several circumstances.

This project is supported by a Science Education Drug Abuse Partnership Award, Grant Number 1R24DA016357-01, from the National Institute on Drug Abuse,

National Institutes of Health.


1. How is this disease distributed?

Health-related conditions and behaviors are not distributed uniformly in a population. They have unique distributions that can be described by how they are distributed in terms of person, place, and time.

2. What hypotheses might explain the distribution of disease?

Clues for formulating hypotheses can be found by observing the way a health-related condition or behavior is distributed in a population.

3. Is there an association between the hypothesized cause and the disease?

Causal hypotheses can be tested by observing exposures and diseases of people as they go about their daily lives. Information from these observational studies can be used to make and compare rates and identify associations.

4. Is the association causal? Causation is only one explanation for an association between an exposure and a disease. Because observational studies are complicated by factors not controlled by the observer, other explanations also must be considered.

5. What should be done when preventable causes of disease are found?

Policy decisions are based on more than the scientific evidence. Because of competing values - social, economic, ethical, environmental, cultural, and political factors may also be considered.

Essential Questions Enduring Understandings

Where are we?


Controlled Trial

Cohort Study

Case-Control

Cross-Sectional

Observational

Experimental

Review


Controlled Trial

Cohort Study

Case-Control Study

Cross-Sectional Study

Healthy PeopleHealthy People

E

Random Assignment

E

DZ

DZ

DZ

DZ


E

E

DZ

DZ

DZ

DZ

DZ

DZ

E

E

E

E

E

E

DZ

DZ

Review - Flow diagrams of the Four Study Designs


EPI Team Challenges


Controlled Trial

Healthy People

-

Healthy People

E

Random Assignment

E

DZ

DZ

DZ

DZ

Cohort Study

Healthy People

-

Healthy People

E

E

DZ

DZ

DZ

DZ


-

E

E

DZ

DZ

EPI Team Challenge: What’s My Design?

Case-Control Study

-

DZ

DZ

E

E

E

E


DZ DZ

E

E

d

b

ca

Flow Diagram 2x2 Table

&

“fit”

Healthy People

-

Healthy People

E

E

DZ

DZ

DZ

DZ

EPI Team Challenge: Connections Between Flow Diagrams and 2x2 Tables


Controlled Trial

Healthy People

-

Healthy People

E

Random Assignment

E

DZ

DZ

DZ

DZ

Cohort Study

Healthy People

-

Healthy People

E

E

DZ

DZ

DZ

DZ


-

E

E

DZ

DZ

EPI Team Challenge: Which Design Is Best?

Case-Control Study

-

DZ

DZ

E

E

E

E


EPI Team Challenge - What’s My Design?


Time

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

Healthy People

-

Healthy People

E

Random Assignment

E

DZ

DZ

DZ

DZ

Controlled Trial

Time

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

Healthy People

-

Healthy People

E

E

DZ

DZ

DZ

DZ

Cohort Study

Time

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

-

DZ

DZ

E

E

E

E

Case-Control Study

Time

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

-

E

E

DZ


DZ

What’s My Design?

Controlled Trial

Cohort Study

Case-Control Study



Epidemiologist is involved during the entire time from exposure to disease.

Assign treatment and control groups.

Follow through time and compare risk of disease in treatment group with risk of disease in control group.

Give exposure to treatment group, but not controls.

Practice Clue

Trial

What’s My Design?


Assign treatment and control groups.

Clue 1

Begin Epi Team Challenge

Trial

What’s My Design?


Observational

Study

Flow Diagram

DZ

-

DZ

E

E

E

E

Clue 2

Case-Control Study

What’s My Design?


Observational

Study

Flow Diagram

Clue 3

Cohort, Case-Control, and Cross-Sectional Studies

What’s My Design?


Observational

Study

Flow Diagram

E

E

-

DZ

DZClue 4

Cross Sectional Study

What’s My Design?


Follow through time and compare risk of disease in exposed group with risk of disease in the unexposed group.

Clue 5

Trial and Cohort Study

What’s My Design?


Healthy People

Flow Diagram

-

Healthy People

E

E

Random Assignment

Non-Observational

Study

Clue 6

Trial

What’s My Design?


Select a group of people with disease and a similar group of people without disease.

Clue 7

Case-Control Study

What’s My Design?


E

E

DZ

DZ

DZ

DZ

Flow Diagram

Observational

Study

DZ

-

Cohort Study

What’s My Design?

Clue 8



Clue 9

Trial and Cohort Study

What’s My Design?


What’s My Design?

Follow through time and compare risk of disease in treatment group with risk of disease in control group.

Give exposure to treatment group, but not controls.

Trial

Clue 10


Select a study sample.

What’s My Design?

Trial, Cohort Study, Case-Control Study, and Cross-

Sectional Study

Clue 11


Epidemiologist gathers data only at that one point in time.

What’s My Design?


Clue 12


Flow Diagram

-

DZ

DZ

What’s My Design?

Case-Control Study

Clue 13


DZ

DZ

DZ

DZ

Flow Diagram

Cohort Study and Trial

What’s My Design?

Clue 14


Case-Control Study

Epidemiologist is involved after disease has occurred and relies on subjects’ memories to gather information about exposure.

Select a group of people with disease and a similar group of people without the disease.

Compare percent of exposed people in the two groups.

Ask both groups about their exposures in the past.

What’s My Design?

Clue 15


Cohort Study


Select a healthy study sample.

Follow through time and compare risk of disease in exposed group to risk of disease in unexposed group.

Observe who has and has not been exposed.

Clue 16

What’s My Design?



Ask each person about both exposure and disease at that point in time.

Epidemiologist gathers data only at that one point in time.

Disease risk in exposed group is compared to disease risk in unexposed group.

Select a study sample.

Clue 17

What’s My Design?


End Epi Team Challenge

What’s My Design?


Designs, Flow Diagrams, and 2x2 Tables


DZ DZ

E

E

d

b

ca


&

“fit”

Healthy People

-

Healthy People

E

E

DZ

DZ

DZ

DZ

EPI Team Challenge: Designs, Flow Diagrams, and 2x2 Tables


DZ DZ

E

Ea

2x2 Table

Where do these people “fit” in the 2x2 table?

Flow Diagram

Controlled Trial


E

E

DZ

DZ

DZ

DZ

Random Assignment


DZ DZ

E

Eb



E

E

DZ

DZ

DZ

DZ

Random Assignment


Controlled Trial


DZ DZ

E

E

c

Flow Diagram 2x2 TableFlow Diagram


E

E

DZ

DZ

DZ

DZ

Random Assignment


Controlled Trial


DZ DZ

E

E

d

2x2 TableFlow Diagram


E

E

DZ

DZ

DZ

DZ

Random Assignment


Controlled Trial


DZ DZ

E

E

c


Where are these people in the flow diagram?

Cohort Study


E

E

DZ

DZ

DZ

DZ


DZ DZ

E

Ea

2x2 Table


Flow Diagram

Cohort Study

Healthy People

E

E

DZ

DZ

DZ

DZ

Healthy People


DZ DZ

E

E

d



Cohort Study

Healthy People

E

E

DZ

DZ

DZ

DZ

Healthy People


DZ DZ

E

Eb



Cohort Study

Healthy People

E

E

DZ

DZ

DZ

DZ

Healthy People


DZ DZ

E

Ea

Where do these

people go in the

2x2 table?

2x2 Table Flow Diagram

Case-Control Study

DZ

DZ

E

E

E

E


DZ DZ

E

E

c

Where do these

people go in the

2x2 table?

Flow Diagram2x2 Table

Case-Control Study

DZ

DZ

E

E

E

E


Flow Diagram

DZ DZ

E

E b

2x2 Table

Where do these

people go in the

2x2 table?

Case-Control Study

DZ

DZ

E

E

E

E


Flow Diagram

DZ DZ

E

E

d

2x2 Table

Where do these

people go in the

2x2 table?

Case-Control Study

DZ

DZ

E

E

E

E


DZ DZ

E

E aFlow Diagram

2x2 Table

Where do these

people go in the

2x2 table?


E

E

DZ

DZ


DZ DZ

E

E

c

Flow Diagram

2x2 Table

Where do these

people go in the

2x2 table?


E

E

DZ

DZ


DZ DZ

E

E

d

Flow Diagram

2x2 Table

Where do these

people go in the

2x2 table?


E

E

DZ

DZ


DZ DZ

E

Eb

Flow Diagram

2x2 Table

Where do these

people go in the

2x2 table?


E

E

DZ

DZ



Designs, Flow Diagrams, and 2x2 Tables


EPI Team Challenge - Which Design is Best?


Controlled Trial

Healthy People

-

Healthy People

E

Random Assignment

E

DZ

DZ

DZ

DZ

Cohort Study

Healthy People

-

Healthy People

E

E

DZ

DZ

DZ

DZ


-

E

E

DZ

DZ

EPI Team Challenge: Which Design Is Best?

Case-Control Study

-

DZ

DZ

E

E

E

E



Case-Control Study

Cohort Study

Trial

Main WeaknessesMain StrengthsStudy Designs

1 5

62

3 7

84

Epi Team ChallengeWhich Design is Best?



Case-Control Study

Cohort Study

Trial


1 5

62

3 7

84

Cross-Sectional

CohortCase-

Control Controlled

Trial

Epi Team ChallengeWhich Design is Best?



Case-Control Study

Cohort Study

Trial


1 5

62

3 7

84

Fastest

Which study design is the fastest?

Which Design is Best?



Case-Control Study

Cohort Study

Trial


1 5

62

3 7

84

Fastest

Time Consuming

Time Consuming

Which study designs are the most time consuming?




Case-Control Study

Cohort Study

Trial


1 5

62

3 7

84

Fastest

Time Consuming

Most Scientifically Sound

Which study design is the most scientifically sound?

Time Consuming




Case-Control Study

Cohort Study

Trial


1 5

62

3 7

84

Fastest

Time Consuming


Can Study Rare Diseases

Which study design is best for studying rare diseases?

Time Consuming




Case-Control Study

Cohort Study

Trial


1 5

62

3 7

84

Fastest

Time Consuming


Possible Time-Order Confusion



Which study designs do not identify the time order of exposure and disease?

Time Consuming




Case-Control Study

Cohort Study

Trial


1 5

62

3 7

84

Fastest

Time Consuming


Best Measure of Exposure


Least Expensive

Relatively Less Expensive and Relatively Fast

Possible Error in Recalling Exposures

Most Accurate Observational Study

Which Design Is Best?

Time Consuming

Unethical for Harmful exposuresMost Expensive

Most Expensive



Least Confidence in Findings

Good Measure of Exposure

It depends ….



It depends . . .

regulations

time urgency

how much is known about the association

money

whether the exposure is believed to be beneficial

. . . on the situation regarding



What Design is Best?


Final Review - could be a test


4 Study Designs

2nd

3rd

4thWeaker

Stronger1st

Randomized Trial

Cohort Study

Case-Control Study




4 Study Designs

2nd

3rd

Longest

Time

Shortest

Time

1st


Case-Control Study

Cohort Study

Trial


3rd


4 Study Designs

2nd

3rd

4th

Most

Expensive

Least

Expensive

1st Cohort Study

Case-Control Study



Case-Control Study

Cohort Study

Trial



4 Study Designs

2nd

3rd

4th

Least

Accurate

Most

Accurate

1st Cohort Study

Case-Control Study


Trial

Cohort Study

Case-Control Study




4 Study Designs

2nd

3rd

4th

Least

Sound

Most

Sound

1st

Trial

Cohort Study

Case-Control Study




CDC

Does this all make sense

to you?

There are four basic study designs for testing hypotheses.

Each design has a different plan for assessing exposure and disease.

The plan for each design can be understood by: 1) thinking of a train ride from exposure to disease, and 2) constructing a flow diagram.

Whatever the study design, the assessment of exposure and disease “fits” into a 2x2 table so that a sample’s exposure and disease can be classified, risks calculated, risks compared, and inferences made.

Review - Making Sense


Big Ideas in this Lesson (3-6)

Big Ideas

The flow diagrams show how each study design is carried out in time

Each study design can be expressed in a 2x2 table format that connects to the depiction in the flow diagram

Each study design has strengths, limitations, and trade-offs. Usually, the studies with greater scientific rigor also have higher costs and time to completion. Choice of study designs depends on several circumstances.

This project is supported by a Science Education Drug Abuse Partnership Award, Grant Number 1R24DA016357-01, from the National Institute on Drug Abuse,

National Institutes of Health.

Re-Cap


1. How is this disease distributed?

Health-related conditions and behaviors are not distributed uniformly in a population. They have unique distributions that can be described by how they are distributed in terms of person, place, and time.

2. What hypotheses might explain the distribution of disease?


3. Is there an association between the hypothesized cause and the disease?


4. Is the association causal?

Causation is only one explanation for an association between an exposure and a disease. Because observational studies are complicated by factors not controlled by the observer, other explanations also must be considered.

5. What should be done when preventable causes of disease are found?

Policy decisions are based on more than the scientific evidence. Because of competing values - social, economic, ethical, environmental, cultural, and political factors may also be considered.

Essential Questions Enduring Understandings

Next Lesson


What hypotheses might explain the distribution of disease?

Is there an association between the hypothesized cause and the disease?


Is the association causal? Causation is only one explanation for finding an association between an exposure and a disease. Because observational studies are flawed, other explanations must also be considered.

What should be done when preventable causes of disease are found?

Individual and societal health-related decisions are based on more than scientific evidence. Because of competing values, social, economic, and political factors must also be considered.

Did the disease prevention strategy work?

The effectiveness of a strategy can be evaluated by making and comparing rates of disease in populations of people who were and were not exposed to the strategy. Costs, trade-offs and alternative strategies must also be considered.

5.

6.

2.

3.

4.


Next LessonEssential Questions Enduring Understandings

How is this disease distributed?

1. Health-related conditions and behaviors are not distributed uniformly in a population. They have unique distributions that can be described by how they are distributed in terms of person, place, and time.

drugepi 3-6 study design exercises module 3 introduction content area: analytical epidemiology...

Documents

study design elements

study design exercises

choice of study designs

2x2 table lesson

analytical epidemiology

causal hypotheses

hypothesized cause

formulating hypotheses