Randomized Controlled Trials (RCT), Relative Risk

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Chapter objectives

After studying this chapter, you will be able to:

  • Distinguish between anatomy and physiology, and identify several branches of each
  • Describe the structure of the body, from simplest to most complex, in terms of the six levels of organization
  • Identify the functional characteristics of human life
  • Identify the four requirements for human survival
  • Define homeostasis and explain its importance to normal human functioning
  • Use appropriate anatomical terminology to identify key body structures, body regions, and directions in the body
  • Compare and contrast at least four medical imagining techniques in terms of their function and use in medicine

Though you may approach a course in anatomy and physiology strictly as a requirement for your field of study, the knowledge you gain in this course will serve you well in many aspects of your life. An understanding of anatomy and physiology is not only fundamental to any career in the health professions, but it can also benefit your own health. Familiarity with the human body can help you make healthful choices and prompt you to take appropriate action when signs of illness arise. Your knowledge in this field will help you understand news about nutrition, medications, medical devices, and procedures and help you understand genetic or infectious diseases. At some point, everyone will have a problem with some aspect of his or her body and your knowledge can help you to be a better parent, spouse, partner, friend, colleague, or caregiver.

This chapter begins with an overview of anatomy and physiology and a preview of the body regions and functions. It then covers the characteristics of life and how the body works to maintain stable conditions. It introduces a set of standard terms for body structures and for planes and positions in the body that will serve as a foundation for more comprehensive information covered later in the text. It ends with examples of medical imaging used to see inside the living body.

Lect 2: Randomized Controlled Trials (RCT), Relative Risk, Effect Modification

We will teach you how to read and critique medical journal articles using examples from some of the most widely-read medical journals. To critique the medical literature you will need to understand the fundamentals of epidemiologic study design, the sources of bias, and the role of chance. Every discipline has its own jargon. we will cover the terminology used in clinical research, including the basic statistical jargon. The most important concepts are in the lectures and small groups provide you with an opportunity to apply what you have learned from the lecture material to actual medical journal articles.

As future physicians you have an obligation to remain current in your field of practice and to treat patients according to generally accepted standards of care.

Quiz PDF eBook: 
Randomized Controlled Trials (RCT), Relative
Download Epidemiology Lecture #2 Quiz PDF eBook
13 Pages
2014
English US
Educational Materials



Sample Questions from the Randomized Controlled Trials (RCT), Relative Risk Quiz

Question: The following questions are based on what you have learned about cardiovascular disease in Med Foundations I and the assigned article entitled, “A Randomized Trial of Low-Dose Aspirin in the Primary Prevention of Cardiovascular Disease in Women” New England Journal of Medicine 2005; 352: 1293-1304

Choices:

5183

5185

10,368

Cannot be calculated without knowing the number of new cases of hypertension over the ten years of follow?-up.

Cannot be calculated without knowing the number of women who had hypertension before the first study visit.

Question: The following questions are based on what you have learned about cardiovascular disease in Med Foundations I and the assigned article entitled, “A Randomized Trial of Low-Dose Aspirin in the Primary Prevention of Cardiovascular Disease in Women” New England Journal of Medicine 2005; 352: 1293-1304

Choices:

221 per 19,942 person?-years

221 cases

1.1%

1.1% per 19,942 person?-years

221 cases per 19,9420 person-years

Question: The following questions are based on what you have learned about cardiovascular disease in Med Foundations I and the assigned article entitled, “A Randomized Trial of Low-Dose Aspirin in the Primary Prevention of Cardiovascular Disease in Women” New England Journal of Medicine 2005; 352: 1293-1304

Choices:

Observational & interventional

Analytic & observational

Observational & descriptive

Descriptive & analytic

Analytic & interventional

Question: From Table 2 the difference in cumulative incidence of ischemic stroke between the low-dose aspirin and placebo groups was:

Choices:

51 cases

51 cases over ten years

0.26%

0.26% over ten years

51 per 39,876 person?-years

Question: Using the data in Table 2, calculate the number needed to treat with low?-dose aspirin to prevent 1 ischemic stroke.

Choices:

Step 1) Calculate the absolute risk reduction: 221/19,942 . 170/19,934 = 0.0026 or 2.6 fewer cases per 1000 women treated with low?-dose aspirin Step 2)Take the reciprocal of the absolute risk reduction: 1/0.0026=392. Therefore, you would need to treat 392 women with low?-dose aspirin to prevent 1 ischemic stroke.

Question: The following questions are based on what you have learned about cardiovascular disease in Med Foundations I and the assigned article entitled, “A Randomized Trial of Low-Dose Aspirin in the Primary Prevention of Cardiovascular Disease in Women” New England Journal of Medicine 2005; 352: 1293-1304

Choices:

170/19,934 divided by 221/19,942

221/19,942 divided by 170/19,934

170/19,942 divided by 221/19,934

170/39,876 divided by 221/39,876

(170+221) divided by (19,934+19,942)

Question: What was the purpose of conducting subgroup analyses in this study?

Choices:

To determine if the association between aspirin and cardiovascular disease as measured by the relative risk was the same across subgroups based on factors such as age, smoking status, body mass index etc.

Question: Why do investigators use a placebo in clinical trials?

Choices:

It allows the investigators to separate the effect of the medication or procedure tested from the placebo effect (an effect resulting from the power of suggestion). The use of a placebo also helps to blind the study, which prevents the investigator or volunteer from influencing the study results based on prior knowledge of the treatment allocation.

Question: How would you interpret the relative risk of ischemic stroke shown in Table 2?

Choices:

In women, low dose aspirin reduces the ten?-year risk of ischemic stroke by 24%.

Question: The following questions are based on what you have learned about cardiovascular disease in Med Foundations I and the assigned article entitled, “A Randomized Trial of Low-Dose Aspirin in the Primary Prevention of Cardiovascular Disease in Women” New England Journal of Medicine 2005; 352: 1293-1304

Choices:

1.1%

2.4%

221 cases over ten years

0.55%

477 cases per 19,934 person?-years

Question: Randomized?-controlled trials are considered the most valid of the epidemiologic study designs because of what aspect of the design?

Choices:

Randomization

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Source:  Janet, E.A. Forrester, Kwan Ho Kenneth Chui, Steven Cohen, Michael D. Kneeland, Alice Tang, David Tybor. Epidemiology and Biostatistics 2010. (Tufts University OpenCourseWare), http://ocw.tufts.edu/Course/65/ (Accessed 3 May, 2014). License: Creative Commons BY-NC-SA
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