Review Question - QID 210428

Action	Numeric Key	Letter Key	Function Key
Choose 1	1
Choose 2	2
Choose 3	3
Choose 4	4
Choose 5	5
Submit Response			Enter
Previous Question			Left Arrow
Next Question		N	Right Arrow
Open/Close Bookmode		C
Open Image			Spacebar

Observational Studies Case-Control Study Compares patients with and without disease to asses their odds of a certain exposure QID: 210428 (M2.OMB.18.92)

QID 210428 (Type "210428" in App Search)

A physician attempts to study cirrhosis in his state. Using a registry of admitted patients over the last 10 years at the local hospital, he isolates all patients who have been diagnosed with cirrhosis. Subsequently, he contacts this group of patients, asking them to complete a survey assessing their prior exposure to alcohol use, intravenous drug abuse, blood transfusions, personal history of cancer, and other medical comorbidities. An identical survey is given to an equal number of patients in the registry who do not carry a prior diagnosis of cirrhosis. Which of the following is the study design utilized by this physician?

Type & Select Correct Answer

Type in at least one full word to see suggestions list

Case-control study

44%

12/27

Cohort study

1/27

Cross-sectional study

37%

10/27

Meta-analysis

2/27

Randomized controlled trial

1/27

Select Answer to see Preferred Response

Review TC In New Tab

This study is starting with a disease and looking for prior exposures compared to a healthy control group which is a case-control study.

Case-control studies are observational studies (no treatment group) and are almost always retrospective in nature. These studies answer the question; what are the odds that given exposure to a certain risk factor, you will have the disease? The study takes the cases (individuals with the disease) and compares it to controls (individuals without the disease) and looks at exposures in each group. An odds ratio is the typical calculated result from such investigations. An odds ratio is a ratio of the odds that a patient has a disease. Another way of considering this is, "what are the odds that I have a disease given exposure to a risk factor." An example is given below:

The number of subjects with:

Alcohol exposure + cirrhosis = A
Alcohol exposure + no cirrhosis = B

No alcohol exposure + cirrhosis = C
No alcohol exposure + no cirrhosis = D

The odds of having alcohol exposure in patients with cirrhosis is A/C
The odds of having alcohol exposure in patients with no cirrhosis is B/D
The ratio of these 2 odds or the odds ratio is (A/C)/(B/D) which simplifies to AD/BC.

Incorrect Answers:
Answers 2: Cohort study first groups patients by risk factors and then subsequently looks at their outcomes. A cohort study may either be prospective or retrospective. For instance, the above study would have been a cohort study had the investigator first looked at all patients who consume alcohol and then assessed for the presence of the disease of interest.

Answer 3: Cross-sectional study gives prevalence at a point in time by assessing the population. It does not give incidence data and it does not give information about causality. It can be thought of as a "cross-section" of the population at that moment.

Answer 4: Meta-analysis studies combine the results of several different studies using statistical analysis.

Answer 5: Randomized controlled trial is where one group is given a certain treatment modality and the outcomes are compared against a control group that is given placebo or standard of care treatment. This is the gold standard in medical research.

Bullet Summary:
A case-control study compares cases (individuals with the disease) to controls (individuals without the disease) and looks for exposures that could be associated with the outcome of interest.

Rating

Please Rate Question Quality

4.4

(5)