Epidemiology Exam 2

A screening examination was performed on 250 persons for Factor X, which is found in Disease Y. A definitive diagnosis for Disease Y using a biopsy among the 250 persons had been obtained previously. The results are charted below: Disease Present Disease Absent Screening Test, Positive for Factor X 30 40 Screening Test, Negative for Factor X 20 160 What is the specificity of this screening test?

(160/200) *100

Which of the following data sources is most likely to be representative of the general health status of a population?

A population-based morbidity survey

Changing trends in the occurrence of disease may reflect:

All of the above - Changes in exposure to infectious or other agents - Changes in the risk-taking behavior of persons - Changes in treatment or detection programs

Public health surveillance involves all of the following except:

All of the above are part of public health surveillance - Collection of health data - Analysis of health data - Interpretation of health data - Dissemination

As a general rule, a disease is included on a list of notifiable diseases under what conditions?

All of the above conditions warrant reporting the disease - Causes serious morbidity or death - Has the potential to spread - Can be controlled with appropriate intervention

A odds ratio of 3.89 indicates that the exposed had a a 489% increase in risk for the health outcome.

False

If the prevalence of a disease decreases in a population, the negative predictive value of a screening test used on that population will also decrease.

False

Numerous epidemiologic studies have indicated that sex, race and ethnicity do not influence the incidence and/or prevalence of disease.

False

P-values tell us more than confidence intervals and are therefore more highly regarded by epidemiologists.

False

Reliability may be defined as the accuracy or ability of something to measure what it purports to measure.

False

The American Community Survey, which is part of the U.S. Census, contains morbidity data for specific diseases present in the U.S. population.

False

When designing case control studies, it is not important if cases and controls come from the same population-at-risk.

False

A woman sees a physician for an annual pap smear test. The test is negative. Three weeks later, she is diagnosed with cancer of the cervix by biopsy. The result of the original screening test was a ______.

False negative

Which of the following best reflect validity of a test?

How well the test measures what it is supposed to measure.

A new blood test has been developed to screen for disease Z. Researchers establish 50 units as a cut point above which a test is considered positive and thereby indicative of disease. The test manufacturers determine that the test's sensitivity is unacceptably low. However, the manufacturers are not concerned with the specificity and do not want the cost of the test to rise. How can they improve the sensitivity of the test?

Lower the cut-point below 50 units.

This type of screening test that is often performed on total populations:

Mass screaning

The following data is from a case-control study, examining if children with leukemia were more likely to have lived in homes with low Electro-Magnetic Frequency exposure (from nearby power lines and transformers) than children without leukemia. Leukemia - Yes Leukemia - No totals EMF- yes 7 92 99 EMF - no 2 87 89 totals 9 179 188 Which of the following uses the correct formula to calculate the odds ratio from the data presented above?

OR = (7*87)/(2*92)

Which is NOT a common way of stating or presenting a research hypotheses?

Open-ended Question

Incident cases are typically preferred over prevalence cases for use in Case Control studies because they reduce the chance of recall bias and the over-representation of cases with long duration of disease.

True

Low-income individuals typically suffer higher rates of morbidity, higher infant mortality, and have lower life expectancy than the wealthy.

True

Screening tests attempt to identify illness in an individual who does not have clinical signs of disease.

True

Secular trends are changes in the frequency and pattern of disease over long periods of time (10+ years).

True

The National Health and Nutrition Examination Surveillance Survey (NHANES) is part of the National Health Survey.

True

The major categories of descriptive epidemiologic variables are person, place, and time.

True

Yield is the amount of previously unrecognized disease that is identified by a screening test.

True

You can increase the yield of a screening test by using it on high risk populations who are likely to have a greater undiagnosed prevalence of disease.

True

Is this odds ratio statistically significant, with a p-value at or below 0.05? OR = 4.57 (95% CI: 2.60, 6.38)

Yes, the odds ratio is statistically significant and has a p-value at or below 0.05.

Which of the following is NOT an activity of descriptive epidemiology?

Evaluating the effects of an assigned intervention on an outcome of interest

Disease codes have changed over time, which can make it difficult to compare older death data (i.e., gathered around 1900, 1910 or so), with that collected today.

True

The adverse consequences of using an invasive screening test which has a low specificity include: (Pick all that apply)

- Possible psychological trauma that accompanies suspicion of a disease. - Increased costs of further diagnostic services. - Increased costs of follow-up with patients.

What would be the best (e.g., most representative of the population, detailed, accurate) source for data on cancer incidence?

Disease registries

In general, descriptive study designs do not provide adequate evidence to satisfy Hill's criteria of temporality.

True

Inaccuracies that have sometimes been associated with death data include race as well as cause of death.

True

The national vital statistics currently consists of:

Births, Deaths

Describing health-related states or events by person, place and time allows us to do all of the following except:

Confirm causal associations

Which of the following best reflects reliability?

Repeatability

Which of the following best defines length bias?

Slow-progressing cases of disease with a better prognosis are more likely to be identified than faster-progressing cases of disease with a poorer prognosis. Thus, cases diagnosed through screening tend to have a better prognosis than the average of all cases.

Which of the following best describes a P value?

The probability that an effect as large, or larger, than that observed in a particular study could have occurred by chance alone given that there is truly no relationship between the exposure and diseases.

Data that is collected by someone other than the investigator are referred to as secondary data.

True

De-identified data hides protected health information from researchers.

True