Module 3 Introduction Content Area: Analytical Epidemiology

1. Module 3 Introduction Content Area: Analytical Epidemiology Essential 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 Table Lesson 3-2: Experimental Study - Buprenorphine Example Lesson 3-3: An Actual Randomized Controlled Trial Lesson 3-4: Observational Studies of Natural Experiments - Sensation-Seeking Example Lesson 3-5: Fundamentals of Study Design Lesson 3-6: Study Design Exercises

2. Module 3 - Analytical Epidemiology • Lesson 3-5 Fundamentals of Study Design • Content • Introduction to concepts of epidemiology study designs • Overview of the four main study designs used in epidemiology: 1) controlled trial; 2) cohort study; 3) case-control study; and 4) cross-sectional study • Ways of explaining the flow of each study design, in text and visually • The uncovering of the strengths and limitations of each design • Examples of how each design can be applied to evaluating the effectiveness of student drug testing programs • Practice in identifying each study design • Big Ideas • Each study design can be expressed in a 2x2 table format • Each study design has a different plan for assessing exposure and disease • The experimental design is the most scientifically rigorous and the observational study designs vary in rigor from quite good to poor • There is a trade-off between scientifically stronger studies that take more effort and money to conduct well, and the less scientific studies that are “quicker and dirtier” 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.

3. Where are we? Essential Questions Enduring Understandings

4. Study Designs in Epidemiology The Journey

5. DZ DZ DZ DZ Review – What is in your epidemiology Toolbox so far? Descriptive Epidemiology Describes those who have the outcome (PPT) Generates hypotheses Surveillance: A way to obtain descriptive information – Example: National Survey on Drug Use and Health

6. No Disease Disease Total Exposed Not Exposed Review – What is in your epidemiology Toolbox so far? Analytic Epidemiology . . . Tests hypotheses Needs an unexposed comparison group Uses the 2x2 table to calculate rates and compare risks in exposed/unexposed However . . . The 2x2 table does not show how the study was done (study design does this)

7. This Lesson Study Designs in Epidemiology Procedures and methods, established beforehand, that are followed by the investigators conducting the study

8. CDC Preview There are four basic study designs for testing hypotheses. This will all make sense to you! Each design has a different plan for assessing exposure and disease. The plan for each design can be understood by constructing a flow diagram. Whatever the study design and its flow diagram, it can be “fit” into a 2x2 table so that risks can be calculated and compared (RR).

9. Experimental Controlled Trial Cohort Case-Control Observational Cross-Sectional Four Basic Study Designs Study Designs in Epidemiology

10. Review of Important Concepts Controlled Trial (a planned experiment) An epidemiologic experiment in which subjects are assigned into groups to receive or not receive a hypothesized beneficial intervention. Examples in Lessons 3-2 and 3-3: Buprenorphine in the treatment of heroin addiction

11. Epidemiologist Board of Education Scenario Research suggests a relationship between poor grades and drug use Hypothesis: Smoking marijuana causes memory loss.

12. No Marijuana Marijuana 100 Students Control Group 100 Students Experimental Group Scenario 200 High School Students Measure Memory 4 Months What’s wrong with this picture? Measure Memory Loss 2 x 2 Table, Calculate Risks, and Relative Risk

13. Review of Important Concepts Natural Experiment (unplanned) Naturally occurring circumstances in which groups of people within a population have been exposed to different levels of the hypothesized cause of an outcome.

14. Important Concepts Observational Studies of Natural Experiments A study in which the investigator does not decide who will and will not be exposed and to how much, but rather, observes what exposures occur in free-living people. Examples in Lesson 3-4: Sensation-seeking and high risk behaviors

15. Study Designs in Epidemiology The Journey

16. Analogy

17. Reminder Study Designs in Epidemiology Procedures and methods, established beforehand, that are followed by the investigators conducting the study

18. CDC - Epidemiologists = Medical Detectives

19. When are the passengers identified as exposed or unexposed? Timing E When are the passengers identified as sick or not sick? DZ Study Design – Timing Is Everything When does the epidemiologist start to observe the journey?

20. Studying the Journey E DZ Time It helps to “see” what is happening

21. Design # 1 Controlled Trial (Experimental) As the train journey begins, the epidemiologist gives the exposure to randomly selected passengers and does not give it to the other passengers. The epidemiologist stays on the train during the entire journey and continues to give the exposure to the randomly selected passengers. Throughout the train ride, the epidemiologist keeps track of all passengers (exposed and unexposed) to record which ones develop the disease during the journey.

22. DZ E +++++++++++++++++++++++++++++++++++++++++++++++++++++ +++++++++++++++++++++++++++++++++++++++++++++++++++++++ When are the passengers identified as sick or not sick? DZ Time What’s Happening? Study Design: Controlled Trial When does the epidemiologist start to observe the journey? When are the passengers identified as exposed or unexposed? E

23. DZ E DZ Random Assignment DZ E DZ Time Controlled Trial Flow Diagram Flow Diagram Controlled Trial Healthy People

24. DZ E DZ Random Assignment DZ E DZ Time Evaluating a Student Drug Testing Program Flow Diagram Controlled Trial Healthy People

25. Time Evaluating a Student Drug Testing Program Randomized Controlled Trial Healthy People

26. Reminder Observational Studies of Natural Experiments A study in which the investigator does not decide who will and will not be exposed and to how much, but rather, observes what exposures occur in free-living people.

27. Design # 2 - Cohort Study Just as in the controlled trial, the epidemiologist is on the train during the entire journey. But there is an important difference. The epidemiologist is not telling passengers what to do. Rather, the epidemiologist is just observing them and counting. Passengers are not being told to have or not have an exposure, they are just living their normal lives. The epidemiologist, on the ride for the whole journey, just keeps observing everyone’s exposures and whether or not they develop the disease during the journey.

28. DZ E +++++++++++++++++++++++++++++++++++++++++++++++++++++ ++++++++++++++++++++++++++++++++++++++++++++++++++++++ Time What’s Happening? Study Design: Cohort Study When does the epidemiologist start to observe the journey? When are the passengers identified as exposed or unexposed? E When are the passengers identified as sick or not sick? DZ

29. DZ E DZ DZ E DZ Time Cohort Study Flow Diagram Flow Diagram Cohort Study Healthy People Healthy People

30. DZ E DZ DZ E DZ Time Similarities Flow Diagram Controlled Trial Cohort Study Healthy People Healthy People

31. DZ E DZ DZ E DZ Time Difference Flow Diagram Controlled Trial Cohort Study Random Assignment Healthy People Healthy People

32. DZ E DZ DZ E DZ Time Evaluating a Student Drug Testing Program Flow Diagram Cohort Study Healthy People Healthy People

33. Time Evaluating a Student Drug Testing Program Flow Diagram Cohort Study Healthy People Healthy People

34. Design # 3 - Case-Control Study The epidemiologist is not on the journey. Rather, the epidemiologist is waiting at the train station at the end of the journey. As passengers get off the train, the epidemiologist selects sick passengers for the case group and selects passengers who are similar but not sick for the control group. The epidemiologist then asks each person in the case group and control group questions about their exposures during the train ride. The epidemiologist relies on passengers’ memories of their exposures that occurred during the train ride.

35. ++++++++++++++++++++++++++++++++++++++++++++++++++++ ++++++++++++++++++++++++++++++++++++++++++++++++++++ E DZ Time What’s Happening? Study Design: Case-Control Study When does the epidemiologist start to observe the journey? When are the passengers identified as exposed or unexposed? E When are the passengers identified as sick or not sick? DZ

36. E E E DZ E Time Case-Control Study Flow Diagram Flow Diagram Case-ControlStudy DZ Observational Study

37. E E E DZ E Time Evaluating a Student Drug Testing Program Flow Diagram Case-ControlStudy DZ Observational Study

38. Time Evaluating a Student Drug Testing Program Flow Diagram Case-ControlStudy Observational Study

39. Design # 4 - Cross-Sectional Study The epidemiologist, who has not been on the journey, stops the train somewhere during the trip (kind of like a train robbery) and takes a “snapshot” of all the passengers by asking them whether or not they had the exposure and whether or not they have the disease. Then the epidemiologist leaves the train and goes home to analyze the data from that particular day. The journey continues without the epidemiologist.

40. +++++++++++++++++++++++++++ ++++++++++++++++++++++++ +++++++++++++++++++++++++ +++++++++++++++++++++++ E DZ Time What’s Happening? Study Design: Cross-Sectional Study When does the epidemiologist start to observe the journey? When are the passengers identified as exposed or unexposed? E When are the passengers identified as sick or not sick? DZ

41. E E Time Cross-Sectional Study Flow Diagram DZ Flow Diagram DZ Cross-SectionalStudy Observational Study

42. E E Time Evaluating a Student Drug Testing Program DZ Flow Diagram DZ Cross-SectionalStudy Observational Study

43. Time Evaluating a Student Drug Testing Program Flow Diagram Cross-SectionalStudy Observational Study

44. Summary Controlled Trial Experimental Cohort Study Observational Case-Control Cross-Sectional

45. DZ Trial E +++++++++++++++++++++++++++++++++++++++++++++++++++++ +++++++++++++++++++++++++++++++++++++++++++++++++++++++ DZ Cohort Study E +++++++++++++++++++++++++++++++++++++++++++++++++++++ ++++++++++++++++++++++++++++++++++++++++++++++++++++++ Case-Control Study ++++++++++++++++++++++++++++++++++++++++++++++++++++ ++++++++++++++++++++++++++++++++++++++++++++++++++++ E DZ Cross-Sectional Study +++++++++++++++++++++++++++ ++++++++++++++++++++++++ +++++++++++++++++++++++++ +++++++++++++++++++++++ E DZ Time Four Ways to Study the Journey

46. DZ DZ E DZ E DZ E DZ DZ Random Assignment DZ DZ E E DZ DZ DZ DZ E E E The Four Study Designs Controlled Trial Case-Control Study Healthy People Healthy People Cohort Study Cross-Sectional Study E Healthy People Healthy People E

47. CDC Making Sense There are four basic study designs for testing hypotheses. Does this all make sense to you? Each design has a different plan for assessing exposure and disease. The plan for each design can be understood by constructing a flow diagram. Whatever the study design and its flow diagram, it can be “fit” into a 2x2 table so that risks can be calculated and compared (RR).

48. Re-Cap • Big Ideas in this Lesson (3-5) • Each study design can be expressed in a 2x2 table format • Each study design has a different plan for assessing exposure and disease • The experimental design is the most scientifically rigorous and the observational study designs vary in rigor from quite good to poor • There is a trade-off between scientifically stronger studies that take more effort and money to conduct well, and the less scientific studies that are “quicker and dirtier” 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.

49. Where are we? Next Lesson Learn more about epidemiology study designs in Epi Team Challenges 6.