Chapter 7, Problem 1RQ

Summary Introduction

Introduction: The significance of clinical observations in a group of cases is determined by the report of physicians and the comparison between control group and reference group. Comparison of reports is a necessary element of epidemiologic study and is well represented by the case-control study design.

Answer to Problem 1RQ

Correct answer: “A case-control study is characterized by all given statements except incidence rates may be computed directly.” Hence, option c. is the correct answer.

Explanation of Solution

Reason for the correct answer:

Option c. is given as “Incidence rates may be computed directly”.

The design of case-control study is characterized as follows:

• To examine the possible relation of a certain disease exposure.
• Identification of a group of individual with certain disease that is the case and the group of people without the disease that is the control.
• Then the specific part of the disease case is exposed or not should be determined, and the portion of control is exposed or not should be determined.
• Valuation of previous exposure may be biased.
• The definition of the cases may be difficult.

The incidence rates of the case-study may be computed directly is not the characteristics of case-control study.

Hence the correct answer is option c.

Reasons for incorrect answers:

Option a. is given as, “It is relatively inexpensive compared with most other epidemiologic study designs”. This is the characteristics of case-control study. Hence, option a. is incorrect.

Option b. is given as, “Patients with the disease (cases) are compared with persons without the disease (controls)”. This is the characteristics of case-control study. Hence, option b. is incorrect.

Option d. is given as, “Assessment of past exposure may be biased”. This is the characteristics of case-control study. Hence, option d. is incorrect.

Option e. is given as, “Definition of cases may be difficult”. This is the characteristics of case-control study. Hence, option e. is incorrect.

Hence the options a., b., d. and e. are incorrect.

Conclusion

A case-control study is characterized by relative inexpensive compared with most other epidemiologic study designs, patients with the disease are compared with persons without the disease, the valuation of past exposure may be biased, and the case definition may be difficult.