Epidemiology_RR

Question 0

Bias introduced into a study when a clinician is aware of the patient’s treatment type

Answer 0

Observational bias

Question 1

How do you interpret the 95% confidence interval for a relative risk of 0.582: 95% CI [0.502-0.673]?

Answer 1

These data are consistent with the RRs ranging from 0.502 to 0.673 with a 95% confidence. (In other words, we are confident that the true RR will be between 0.502 and 0.673 95 out of 100 times.)

Question 2

Bias introduced when screening a disease earlier, thus lengthening the time for diagnosis to death

Answer 2

Lead-time bias

Question 3

If you want to know if geographical location affects infant mortality rate, but most variation in infant mortality is predicted by socioeconomic status, then socioeconomic status is a(n) _____.

Answer 3

Confounding factor

Question 4

The proportion of people who have the disease and test positive is the ____.

Answer 4

Sensitivity

Question 5

Sensitive tests have few false negatives and are used to ____a disease.

Answer 5

Out

Question 6

PPD reactivity is used as a screening test because most people with TB (except those who are synergic) will have a positive PPD. Does this mean the PPD screening test is highly sensitive or specific for TB?

Answer 6

Highly sensitive.

Screening tests with high sensitivity are good for diseases with low prevalence.

Question 7

Do chronic diseases, such as SLE, have a higher prevalence or a higher incidence?

Answer 7

Higher prevalence.

Question 8

Do epidemics, such as influenza, have a higher prevalence or a high incidence?

Answer 8

Higher incidence.

Question 9

What is the difference between incidence and prevalence?

Answer 9

Incidence: The percentage of new cases of disease that develop over a given time period among the total population at risk.

Prevalence: The percentage of cases of disease in a population at one snapshot in time.

Question 10

Does a cross-sectional survey measure incidence or prevalence?

Answer 10

Prevalence

Question 11

Does a cohort study measure incidence or prevalence?

Answer 11

Both

Question 12

Does a case-control study measure incidence or prevalence?

Answer 12

Neither

Question 13

Describe a test that consistently gives identical results, but the results are wrong.

Answer 13

High reliability = Precision

Low validity = Accuracy

Question 14

Describe the difference(s) between a cohort and a case-control study.

Answer 14

Cohort study: Can be used to calculate relative risk, and/or odds ratio.

Case-control study: Can be used to calculate an odds ratio, which is an estimate of the relative risk when the disease prevalence is low.

Question 15

What is attributable risk?

Answer 15

This is the difference in risk in the exposed and unexposed groups (i.e. the risk that is attributable to the exposure).

Question 16

What is relative risk?

Answer 16

This is the incidence in the exposure group divided by the incidence in the unexposed group.

Question 17

The results of a hypothetical study found an association between aspirin intake and the risk of heart disease. How do you interpret a relative risk of 1.5?

Answer 17

In patients who took aspirin, the risk of heart disease was 1.5 times that of patients who did not take aspirin.

Question 18

What is an odds ratio?

Answer 18

The odds ratio differs among three types of studies:

1) In cohort studies, the odds of developing the disease in the exposed group divided by the odds of developing the disease in the unexposed group;
2) In case-control studies, the odds that the cases were exposed divided by the odds that the controls were exposed;
3) In cross-sectional studies, the odds that the exposed group has the disease divided by the odds that the unexposed group has the disease.

Question 19

The results of a hypothetical study found an association between aspirin intake and the risk of heart disease. How would you interpret an odds ration of 1.5?

Answer 19

In patients who took aspirin, the odds of acquiring heart disease were 1.5 times those of patients who did not take aspirin.

Question 20

In which patients do you initiate colorectal cancer screening early?

Answer 20

Patients with:

1) Inflammatory Bowel Disease;
2) Familial Adenomatous Polyposis / Hereditary Non-polyposis Colorectal Cancer;
3) First-degree relatives with Adenomatous polyps (<60 years of age) or colorectal cancer

Question 21

What is the most common cancer in men?

What is the most common cause of death from cancer in men?

Answer 21

Prostate cancer is the most common cancer in men, but lung cancer causes more deaths.

Question 22

What is the percentage of cases within 1 standard deviation of the mean? 2 SDs? 3 SDs?

Answer 22

1 SD: 68%
2 SDs: 95.4%
3 SDs: 99.7%

Question 23

How is birth rate quantified?

Answer 23

Number of live births per 1000 population in 1 year

Question 24

How is mortality rate quantified?

Answer 24

Number of deaths per 1000 population in 1 year

Question 25

How is neonatal mortality rate quantified?

Answer 25

Number of deaths from birth to 28 days per 1000 live births in 1 year

Question 26

How is infant mortality rate quantified?

Answer 26

Number of deaths from birth to 1 year of age per 1000 live births in 1 year

This also equals neonatal + postnatal mortality rates.

Question 27

How is maternal mortality rate quantified?

Answer 27

Number of deaths during pregnancy to 90 days postpartum per 100,000 live births in 1 year